summaryrefslogtreecommitdiff
path: root/man/systemd.network.xml
blob: 01d88976384731b79ebbee60b8ea382ca565c384 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->

<refentry id="systemd.network" conditional='ENABLE_NETWORKD'
          xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>systemd.network</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>systemd.network</refentrytitle>
    <manvolnum>5</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemd.network</refname>
    <refpurpose>Network configuration</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <para><filename><replaceable>network</replaceable>.network</filename></para>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>A plain ini-style text file that encodes network configuration for matching network
    interfaces, used by
    <citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
    See <citerefentry><refentrytitle>systemd.syntax</refentrytitle><manvolnum>7</manvolnum></citerefentry>
    for a general description of the syntax.</para>

    <para>The main network file must have the extension <filename>.network</filename>; other
    extensions are ignored. Networks are applied to links whenever the links appear.</para>

    <para>The <filename>.network</filename> files are read from the files located in the system network
    directories <filename>/usr/lib/systemd/network</filename> and
    <filename>/usr/local/lib/systemd/network</filename>, the volatile runtime network directory
    <filename>/run/systemd/network</filename> and the local administration network directory
    <filename>/etc/systemd/network</filename>. All configuration files are collectively sorted and
    processed in alphanumeric order, regardless of the directories in which they live. However, files
    with identical filenames replace each other. It is recommended that each filename is prefixed with
    a number (e.g. <filename>10-eth0.network</filename>). Otherwise, the default
    <filename>.network</filename> files or those generated by
    <citerefentry><refentrytitle>systemd-network-generator.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    may take precedence over user configured files. Files in <filename>/etc/</filename> have the highest
    priority, files in <filename>/run/</filename> take precedence over files with the same name under
    <filename>/usr/</filename>. This can be used to override a system-supplied configuration file with
    a local file if needed. As a special case, an empty file (file size 0) or symlink with the same
    name pointing to <filename>/dev/null</filename> disables the configuration file entirely (it is
    "masked").</para>

    <para>Along with the network file <filename>foo.network</filename>, a "drop-in" directory
    <filename>foo.network.d/</filename> may exist. All files with the suffix
    <literal>.conf</literal> from this directory will be merged in the alphanumeric order and parsed
    after the main file itself has been parsed. This is useful to alter or add configuration settings,
    without having to modify the main configuration file. Each drop-in file must have appropriate
    section headers.</para>

    <para>In addition to <filename>/etc/systemd/network</filename>, drop-in <literal>.d</literal>
    directories can be placed in <filename>/usr/lib/systemd/network</filename> or
    <filename>/run/systemd/network</filename> directories. Drop-in files in
    <filename>/etc/</filename> take precedence over those in <filename>/run/</filename> which in turn
    take precedence over those in <filename>/usr/lib/</filename>. Drop-in files under any of these
    directories take precedence over the main network file wherever located.</para>
  </refsect1>

  <refsect1>
    <title>[Match] Section Options</title>

    <para>The network file contains a [Match] section, which determines if a given network file may
    be applied to a given interface; and a [Network] section specifying how the interface should be
    configured. The first (in alphanumeric order) of the network files that matches a given interface
    is applied, all later files are ignored, even if they match as well.</para>

    <para>A network file is said to match a network interface if all matches specified by the [Match]
    section are satisfied. When a network file does not contain valid settings in [Match] section, then
    the file will match all interfaces and <command>systemd-networkd</command> warns about that. Hint:
    to avoid the warning and to make it clear that all interfaces shall be matched, add the following:
    <programlisting>Name=*</programlisting> The following keys are accepted:</para>

    <variablelist class='network-directives'>
      <xi:include href="systemd.link.xml" xpointer="mac-address" />
      <xi:include href="systemd.link.xml" xpointer="permanent-mac-address" />
      <xi:include href="systemd.link.xml" xpointer="path" />
      <xi:include href="systemd.link.xml" xpointer="driver" />
      <xi:include href="systemd.link.xml" xpointer="type" />
      <xi:include href="systemd.link.xml" xpointer="kind" />
      <xi:include href="systemd.link.xml" xpointer="property" />

      <varlistentry>
        <term><varname>Name=</varname></term>
        <listitem>
          <para>A whitespace-separated list of shell-style globs matching the device name, as exposed
          by the udev property <literal>INTERFACE</literal>, or device's alternative names. If the
          list is prefixed with a "!", the test is inverted.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>WLANInterfaceType=</varname></term>
        <listitem>
          <para>A whitespace-separated list of wireless network type. Supported values are
          <literal>ad-hoc</literal>, <literal>station</literal>, <literal>ap</literal>,
          <literal>ap-vlan</literal>, <literal>wds</literal>, <literal>monitor</literal>,
          <literal>mesh-point</literal>, <literal>p2p-client</literal>, <literal>p2p-go</literal>,
          <literal>p2p-device</literal>, <literal>ocb</literal>, and <literal>nan</literal>. If the
          list is prefixed with a "!", the test is inverted. </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SSID=</varname></term>
        <listitem>
          <para>A whitespace-separated list of shell-style globs matching the SSID of the currently
          connected wireless LAN. If the list is prefixed with a "!", the test is inverted.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>BSSID=</varname></term>
        <listitem>
          <para>A whitespace-separated list of hardware address of the currently connected wireless
          LAN. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example in
          <varname>MACAddress=</varname>. This option may appear more than once, in which case the
          lists are merged. If the empty string is assigned to this option, the list is reset.</para>
        </listitem>
      </varlistentry>

      <xi:include href="systemd.link.xml" xpointer="host" />
      <xi:include href="systemd.link.xml" xpointer="virtualization" />
      <xi:include href="systemd.link.xml" xpointer="kernel-command-line" />
      <xi:include href="systemd.link.xml" xpointer="kernel-version" />
      <xi:include href="systemd.link.xml" xpointer="credential" />
      <xi:include href="systemd.link.xml" xpointer="architecture" />
      <xi:include href="systemd.link.xml" xpointer="firmware" />
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[Link] Section Options</title>

    <para>The [Link] section accepts the following keys:</para>

    <variablelist class='network-directives'>
      <varlistentry>
        <term><varname>MACAddress=</varname></term>
        <listitem>
          <para>The hardware address to set for the device.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MTUBytes=</varname></term>
        <listitem>
          <para>The maximum transmission unit in bytes to set for the device. The usual suffixes K, M,
          G, are supported and are understood to the base of 1024.</para>
          <para>Note that if IPv6 is enabled on the interface, and the MTU is chosen below 1280 (the
          minimum MTU for IPv6) it will automatically be increased to this value.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>ARP=</varname></term>
        <listitem>
          <para>Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol)
          for this interface is enabled. When unset, the kernel's default will be used.</para>
          <para> For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual
          interfaces atop a single lower-level physical interface, which will then only serve as a
          link/"bridge" device aggregating traffic to the same physical link and not participate in
          the network otherwise. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Multicast=</varname></term>
        <listitem>
          <para>Takes a boolean. If set to true, the multicast flag on the device is enabled. Defaults
          to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>AllMulticast=</varname></term>
        <listitem>
          <para>Takes a boolean. If set to true, the driver retrieves all multicast packets from the
          network. This happens when multicast routing is enabled. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Promiscuous=</varname></term>
        <listitem>
          <para>Takes a boolean. If set to true, promiscuous mode of the interface is enabled. Defaults
          to unset.</para>
          <para>If this is set to false for the underlying link of a <literal>passthru</literal> mode
          MACVLAN/MACVTAP, the virtual interface will be created with the <literal>nopromisc</literal>
          flag set.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Unmanaged=</varname></term>
        <listitem>
          <para>Takes a boolean. When <literal>yes</literal>, no attempts are made to bring up or
          configure matching links, equivalent to when there are no matching network files. Defaults to
          <literal>no</literal>.</para>
          <para>This is useful for preventing later matching network files from interfering with
          certain interfaces that are fully controlled by other applications.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Group=</varname></term>
        <listitem>
          <para>Link groups are similar to port ranges found in managed switches. When network
          interfaces are added to a numbered group, operations on all the interfaces from that group
          can be performed at once. Takes an unsigned integer in the range 0…2147483647. Defaults to
          unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RequiredForOnline=</varname></term>
        <listitem>
          <para>Takes a boolean or a minimum operational state and an optional maximum operational
          state. Please see
          <citerefentry><refentrytitle>networkctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
          for possible operational states. When <literal>yes</literal>, the network is deemed required
          when determining whether the system is online (including when running
          <command>systemd-networkd-wait-online</command>). When <literal>no</literal>, the network is
          ignored when determining the online state. When a minimum operational state and an optional
          maximum operational state are set, <literal>yes</literal> is implied, and this controls the
          minimum and maximum operational state required for the network interface to be considered
          online.</para>

          <para>Defaults to <literal>yes</literal> when <varname>ActivationPolicy=</varname> is not
          set, or set to <literal>up</literal>, <literal>always-up</literal>, or
          <literal>bound</literal>. Defaults to <literal>no</literal> when
          <varname>ActivationPolicy=</varname> is set to <literal>manual</literal> or
          <literal>down</literal>. This is forced to <literal>no</literal> when
          <varname>ActivationPolicy=</varname> is set to <literal>always-down</literal>.</para>

          <para>The network will be brought up normally (as configured by
          <varname>ActivationPolicy=</varname>), but in the event that there is no address being
          assigned by DHCP or the cable is not plugged in, the link will simply remain offline and be
          skipped automatically by <command>systemd-networkd-wait-online</command> if
          <literal>RequiredForOnline=no</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RequiredFamilyForOnline=</varname></term>
        <listitem>
          <para>Takes an address family. When specified, an IP address in the given family is deemed
          required when determining whether the link is online (including when running
          <command>systemd-networkd-wait-online</command>). Takes one of <literal>ipv4</literal>,
          <literal>ipv6</literal>, <literal>both</literal>, or <literal>any</literal>. Defaults to
          <literal>any</literal>. Note that this option has no effect if
          <literal>RequiredForOnline=no</literal>, or if <literal>RequiredForOnline=</literal>
          specifies a minimum operational state below <literal>degraded</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>ActivationPolicy=</varname></term>
        <listitem>
          <para>Specifies the policy for <command>systemd-networkd</command> managing the link
          administrative state. Specifically, this controls how <command>systemd-networkd</command>
          changes the network device's <literal>IFF_UP</literal> flag, which is sometimes
          controlled by system administrators by running e.g.,
          <command>ip link set dev eth0 up</command> or <command>ip link set dev eth0 down</command>,
          and can also be changed with <command>networkctl up eth0</command> or
          <command>networkctl down eth0</command>.</para>

          <para>Takes one of <literal>up</literal>, <literal>always-up</literal>,
          <literal>manual</literal>, <literal>always-down</literal>, <literal>down</literal>,
          or <literal>bound</literal>. When <literal>manual</literal>,
          <command>systemd-networkd</command> will not change the link's admin state automatically;
          the system administrator must bring the interface up or down manually, as desired. When
          <literal>up</literal> (the default) or <literal>always-up</literal>, or
          <literal>down</literal> or <literal>always-down</literal>,
          <command>systemd-networkd</command> will set the link up or down, respectively, when the
          interface is (re)configured. When <literal>always-up</literal> or
          <literal>always-down</literal>, <command>systemd-networkd</command> will set the link up or
          down, respectively, any time <command>systemd-networkd</command> detects a change in the
          administrative state. When <varname>BindCarrier=</varname> is also set, this is automatically
          set to <literal>bound</literal> and any other value is ignored.</para>

          <para>When the policy is set to <literal>down</literal> or <literal>manual</literal>, the
          default value of <varname>RequiredForOnline=</varname> is <literal>no</literal>. When the
          policy is set to <literal>always-down</literal>, the value of
          <varname>RequiredForOnline=</varname> forced to <literal>no</literal>.</para>

          <para>The administrative state is not the same as the carrier state, so using
          <literal>always-up</literal> does not mean the link will never lose carrier. The link carrier
          depends on both the administrative state as well as the network device's physical connection.
          However, to avoid reconfiguration failures, when using <literal>always-up</literal>,
          <varname>IgnoreCarrierLoss=</varname> is forced to true.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <xi:include href="systemd.link.xml" xpointer="sr-iov" />

  <refsect1>
    <title>[Network] Section Options</title>

    <para>The [Network] section accepts the following keys:</para>

    <variablelist class='network-directives'>
      <varlistentry>
        <term><varname>Description=</varname></term>
        <listitem>
          <para>A description of the device. This is only used for presentation purposes.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DHCP=</varname></term>
        <listitem>
          <para>Enables DHCPv4 and/or DHCPv6 client support. Accepts <literal>yes</literal>,
          <literal>no</literal>, <literal>ipv4</literal>, or <literal>ipv6</literal>. Defaults to
          <literal>no</literal>.</para>

          <para>Note that DHCPv6 will by default be triggered by Router Advertisements, if reception is
          enabled, regardless of this parameter. By explicitly enabling DHCPv6 support here, the DHCPv6
          client will be started in the mode specified by the <varname>WithoutRA=</varname> setting in the
          [DHCPv6] section, regardless of the presence of routers on the link, or what flags the routers
          pass. See <varname>IPv6AcceptRA=</varname>.</para>

          <para>Furthermore, note that by default the domain name specified through DHCP is not used
          for name resolution. See option <option>UseDomains=</option> below.</para>

          <para>See the [DHCPv4] or [DHCPv6] sections below for further configuration options for the
          DHCP client support.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DHCPServer=</varname></term>
        <listitem>
          <para>Takes a boolean. If set to <literal>yes</literal>, DHCPv4 server will be started.
          Defaults to <literal>no</literal>. Further settings for the DHCP server may be set in the
          [DHCPServer] section described below.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>LinkLocalAddressing=</varname></term>
        <listitem>
          <para>Enables link-local address autoconfiguration. Accepts <option>yes</option>,
          <option>no</option>, <option>ipv4</option>, and <option>ipv6</option>. An IPv6 link-local
          address is configured when <option>yes</option> or <option>ipv6</option>. An IPv4 link-local
          address is configured when <option>yes</option> or <option>ipv4</option> and when DHCPv4
          autoconfiguration has been unsuccessful for some time. (IPv4 link-local address
          autoconfiguration will usually happen in parallel with repeated attempts to acquire a DHCPv4
          lease).</para>

          <para>Defaults to <option>no</option> when <varname>KeepMaster=</varname> or
          <varname>Bridge=</varname> is set or when the specified
          <varname>MACVLAN=</varname>/<varname>MACVTAP=</varname> has <varname>Mode=passthru</varname>,
          or <option>ipv6</option> otherwise.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv6LinkLocalAddressGenerationMode=</varname></term>
        <listitem>
          <para>Specifies how IPv6 link-local address is generated. Takes one of
          <literal>eui64</literal>, <literal>none</literal>, <literal>stable-privacy</literal> and
          <literal>random</literal>. When unset, <literal>stable-privacy</literal> is used if
          <varname>IPv6StableSecretAddress=</varname> is specified, and if not,
          <literal>eui64</literal> is used. Note that if <varname>LinkLocalAddressing=</varname> is
          <literal>no</literal> or <literal>ipv4</literal>, then
          <varname>IPv6LinkLocalAddressGenerationMode=</varname> will be ignored. Also, even if
          <varname>LinkLocalAddressing=</varname> is <literal>yes</literal> or <literal>ipv6</literal>,
          setting <varname>IPv6LinkLocalAddressGenerationMode=none</varname>
          disables to configure an IPv6 link-local address.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv6StableSecretAddress=</varname></term>
        <listitem>
          <para>Takes an IPv6 address. The specified address will be used as a stable secret for
          generating IPv6 link-local address. If this setting is specified, and
          <varname>IPv6LinkLocalAddressGenerationMode=</varname> is unset, then
          <varname>IPv6LinkLocalAddressGenerationMode=stable-privacy</varname> is implied.
          If this setting is not specified, and <literal>stable-privacy</literal> is set to
          <varname>IPv6LinkLocalAddressGenerationMode=</varname>,
          then a stable secret address will be generated from the local machine ID and the interface
          name.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv4LLStartAddress=</varname></term>
        <listitem>
          <para>Specifies the first IPv4 link-local address to try. Takes an IPv4 address for example
          169.254.1.2, from the link-local address range: 169.254.0.0/16 except for 169.254.0.0/24 and
          169.254.255.0/24. This setting may be useful if the device should always have the same address
          as long as there is no address conflict. When unset, a random address will be automatically
          selected. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv4LLRoute=</varname></term>
        <listitem>
          <para>Takes a boolean. If set to true, sets up the route needed for non-IPv4LL hosts to
          communicate with IPv4LL-only hosts. Defaults to false.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DefaultRouteOnDevice=</varname></term>
        <listitem>
          <para>Takes a boolean. If set to true, sets up the IPv4 default route bound to the interface.
          Defaults to false. This is useful when creating routes on point-to-point interfaces. This is
          equivalent to e.g. the following,
          <programlisting>ip route add default dev veth99</programlisting>
          or,
          <programlisting>[Route]
Gateway=0.0.0.0</programlisting></para>
          <para>Currently, there are no way to specify e.g., the table for the route configured by this
          setting. To configure the default route with such an additional property, please use the
          following instead:
          <programlisting>[Route]
Gateway=0.0.0.0
Table=1234</programlisting></para>
          <para>If you'd like to create an IPv6 default route bound to the interface, please use the
          following:
          <programlisting>[Route]
Gateway=::
Table=1234</programlisting></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>LLMNR=</varname></term>
        <listitem>
          <para>Takes a boolean or <literal>resolve</literal>. When true, enables
          <ulink url="https://tools.ietf.org/html/rfc4795">Link-Local Multicast Name Resolution</ulink>
          on the link. When set to <literal>resolve</literal>, only resolution is enabled, but not host
          registration and announcement. Defaults to true. This setting is read by
          <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MulticastDNS=</varname></term>
        <listitem>
          <para>Takes a boolean or <literal>resolve</literal>. When true, enables
          <ulink url="https://tools.ietf.org/html/rfc6762">Multicast DNS</ulink> support on the link.
          When set to <literal>resolve</literal>, only resolution is enabled, but not host or service
          registration and announcement. Defaults to false. This setting is read by
          <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DNSOverTLS=</varname></term>
        <listitem>
          <para>Takes a boolean or <literal>opportunistic</literal>. When true, enables
          <ulink url="https://tools.ietf.org/html/rfc7858">DNS-over-TLS</ulink> support on the link.
          When set to <literal>opportunistic</literal>, compatibility with non-DNS-over-TLS servers is
          increased, by automatically turning off DNS-over-TLS servers in this case. This option
          defines a per-interface setting for
          <citerefentry><refentrytitle>resolved.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
          global <varname>DNSOverTLS=</varname> option. Defaults to unset, and the global setting will
          be used. This setting is read by
          <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DNSSEC=</varname></term>
        <listitem>
          <para>Takes a boolean or <literal>allow-downgrade</literal>. When true, enables
          <ulink url="https://tools.ietf.org/html/rfc4033">DNSSEC</ulink> DNS validation support on the
          link. When set to <literal>allow-downgrade</literal>, compatibility with non-DNSSEC capable
          networks is increased, by automatically turning off DNSSEC in this case. This option defines
          a per-interface setting for
          <citerefentry><refentrytitle>resolved.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
          global <varname>DNSSEC=</varname> option. Defaults to unset, and the global setting will be
          used. This setting is read by
          <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DNSSECNegativeTrustAnchors=</varname></term>
        <listitem>
          <para>A space-separated list of DNSSEC negative trust anchor domains. If specified and DNSSEC
          is enabled, look-ups done via the interface's DNS server will be subject to the list of
          negative trust anchors, and not require authentication for the specified domains, or anything
          below it. Use this to disable DNSSEC authentication for specific private domains, that cannot
          be proven valid using the Internet DNS hierarchy. Defaults to the empty list. This setting is
          read by
          <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>LLDP=</varname></term>
        <listitem>
          <para>Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol
          commonly implemented on professional routers and bridges which announces which physical port
          a system is connected to, as well as other related data. Accepts a boolean or the special
          value <literal>routers-only</literal>. When true, incoming LLDP packets are accepted and a
          database of all LLDP neighbors maintained. If <literal>routers-only</literal> is set only
          LLDP data of various types of routers is collected and LLDP data about other types of devices
          ignored (such as stations, telephones and others). If false, LLDP reception is disabled.
          Defaults to <literal>routers-only</literal>. Use
          <citerefentry><refentrytitle>networkctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
          to query the collected neighbor data. LLDP is only available on Ethernet links. See
          <varname>EmitLLDP=</varname> below for enabling LLDP packet emission from the local system.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>EmitLLDP=</varname></term>
        <listitem>
          <para>Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the
          special values <literal>nearest-bridge</literal>, <literal>non-tpmr-bridge</literal> and
          <literal>customer-bridge</literal>. Defaults to false, which turns off LLDP packet emission.
          If not false, a short LLDP packet with information about the local system is sent out in
          regular intervals on the link. The LLDP packet will contain information about the local
          hostname, the local machine ID (as stored in
          <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
          and the local interface name, as well as the pretty hostname of the system (as set in
          <citerefentry><refentrytitle>machine-info</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
          LLDP emission is only available on Ethernet links. Note that this setting passes data
          suitable for identification of host to the network and should thus not be enabled on
          untrusted networks, where such identification data should not be made available. Use this
          option to permit other systems to identify on which interfaces they are connected to this
          system. The three special values control propagation of the LLDP packets. The
          <literal>nearest-bridge</literal> setting permits propagation only to the nearest connected
          bridge, <literal>non-tpmr-bridge</literal> permits propagation across Two-Port MAC Relays,
          but not any other bridges, and <literal>customer-bridge</literal> permits propagation until
          a customer bridge is reached. For details about these concepts, see
          <ulink url="https://standards.ieee.org/findstds/standard/802.1AB-2016.html">IEEE 802.1AB-2016</ulink>.
          Note that configuring this setting to true is equivalent to
          <literal>nearest-bridge</literal>, the recommended and most restricted level of propagation.
          See <varname>LLDP=</varname> above for an option to enable LLDP reception.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>BindCarrier=</varname></term>
        <listitem>
          <para>A link name or a list of link names. When set, controls the behavior of the current
          link. When all links in the list are in an operational down state, the current link is
          brought down. When at least one link has carrier, the current interface is brought up.</para>

          <para>This forces <varname>ActivationPolicy=</varname> to be set to <literal>bound</literal>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Address=</varname></term>
        <listitem>
          <para>A static IPv4 or IPv6 address and its prefix length, separated by a
          <literal>/</literal> character. Specify this key more than once to configure several
          addresses. The format of the address must be as described in
          <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
          This is a short-hand for an [Address] section only containing an Address key (see below).
          This option may be specified more than once.</para>

          <para>If the specified address is <literal>0.0.0.0</literal> (for IPv4) or
          <literal>::</literal> (for IPv6), a new address range of the requested size is automatically
          allocated from a system-wide pool of unused ranges. Note that the prefix length must be equal
          or larger than 8 for IPv4, and 64 for IPv6. The allocated range is checked against all
          current network interfaces and all known network configuration files to avoid address range
          conflicts. The default system-wide pool consists of 192.168.0.0/16, 172.16.0.0/12 and
          10.0.0.0/8 for IPv4, and fd00::/8 for IPv6. This functionality is useful to manage a large
          number of dynamically created network interfaces with the same network configuration and
          automatic address range assignment.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Gateway=</varname></term>
        <listitem>
          <para>The gateway address, which must be in the format described in
          <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
          This is a short-hand for a [Route] section only containing a <varname>Gateway=</varname> key.
          This option may be specified more than once.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DNS=</varname></term>
        <listitem>
          <para>A DNS server address, which must be in the format described in
          <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
          This option may be specified more than once. Each address can optionally take a port number
          separated with <literal>:</literal>, a network interface name or index separated with
          <literal>%</literal>, and a Server Name Indication (SNI) separated with <literal>#</literal>.
          When IPv6 address is specified with a port number, then the address must be in the square
          brackets. That is, the acceptable full formats are
          <literal>111.222.333.444:9953%ifname#example.com</literal> for IPv4 and
          <literal>[1111:2222::3333]:9953%ifname#example.com</literal> for IPv6. If an empty string is
          assigned, then the all previous assignments are cleared. This setting is read by
          <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Domains=</varname></term>
        <listitem>
          <para>A whitespace-separated list of domains which should be resolved using the DNS servers
          on this link. Each item in the list should be a domain name, optionally prefixed with a tilde
          (<literal>~</literal>). The domains with the prefix are called "routing-only domains". The
          domains without the prefix are called "search domains" and are first used as search suffixes
          for extending single-label hostnames (hostnames containing no dots) to become fully qualified
          domain names (FQDNs). If a single-label hostname is resolved on this interface, each of the
          specified search domains are appended to it in turn, converting it into a fully qualified
          domain name, until one of them may be successfully resolved.</para>

          <para>Both "search" and "routing-only" domains are used for routing of DNS queries: look-ups
          for hostnames ending in those domains (hence also single label names, if any "search domains"
          are listed), are routed to the DNS servers configured for this interface. The domain routing
          logic is particularly useful on multi-homed hosts with DNS servers serving particular private
          DNS zones on each interface.</para>

          <para>The "routing-only" domain <literal>~.</literal> (the tilde indicating definition of a
          routing domain, the dot referring to the DNS root domain which is the implied suffix of all
          valid DNS names) has special effect. It causes all DNS traffic which does not match another
          configured domain routing entry to be routed to DNS servers specified for this interface.
          This setting is useful to prefer a certain set of DNS servers if a link on which they are
          connected is available.</para>

          <para>This setting is read by
          <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
          "Search domains" correspond to the <varname>domain</varname> and <varname>search</varname>
          entries in
          <citerefentry project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
          Domain name routing has no equivalent in the traditional glibc API, which has no concept of
          domain name servers limited to a specific link.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DNSDefaultRoute=</varname></term>
        <listitem>
          <para>Takes a boolean argument. If true, this link's configured DNS servers are used for
          resolving domain names that do not match any link's configured <varname>Domains=</varname>
          setting. If false, this link's configured DNS servers are never used for such domains, and
          are exclusively used for resolving names that match at least one of the domains configured on
          this link. If not specified defaults to an automatic mode: queries not matching any link's
          configured domains will be routed to this link if it has no routing-only domains configured.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>NTP=</varname></term>
        <listitem>
          <para>An NTP server address (either an IP address, or a hostname). This option may be
          specified more than once. This setting is read by
          <citerefentry><refentrytitle>systemd-timesyncd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPForward=</varname></term>
        <listitem>
          <para>Configures IP packet forwarding for the system. If enabled, incoming packets on any
          network interface will be forwarded to any other interfaces according to the routing table.
          Takes a boolean, or the values <literal>ipv4</literal> or <literal>ipv6</literal>, which only
          enable IP packet forwarding for the specified address family. This controls the
          <filename>net.ipv4.ip_forward</filename> and <filename>net.ipv6.conf.all.forwarding</filename>
          sysctl options of the network interface (see
          <ulink url="https://docs.kernel.org/networking/ip-sysctl.html">IP Sysctl</ulink>
          for details about sysctl options). Defaults to <literal>no</literal>.</para>

          <para>Note: this setting controls a global kernel option, and does so one way only: if a
          network that has this setting enabled is set up the global setting is turned on. However,
          it is never turned off again, even after all networks with this setting enabled are shut
          down again.</para>

          <para>To allow IP packet forwarding only between specific network interfaces use a firewall.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPMasquerade=</varname></term>
        <listitem>
          <para>Configures IP masquerading for the network interface. If enabled, packets forwarded
          from the network interface will be appear as coming from the local host. Takes one of
          <literal>ipv4</literal>, <literal>ipv6</literal>, <literal>both</literal>, or
          <literal>no</literal>. Defaults to <literal>no</literal>. If enabled, this automatically sets
          <varname>IPForward=</varname> to one of <literal>ipv4</literal>, <literal>ipv6</literal> or
          <literal>yes</literal>.</para>
          <para>Note. Any positive boolean values such as <literal>yes</literal> or
          <literal>true</literal> are now deprecated. Please use one of the values in the above.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv6PrivacyExtensions=</varname></term>
        <listitem>
          <para>Configures use of stateless temporary addresses that change over time (see
          <ulink url="https://tools.ietf.org/html/rfc4941">RFC 4941</ulink>,
          Privacy Extensions for Stateless Address Autoconfiguration in IPv6). Takes a boolean or the
          special values <literal>prefer-public</literal> and <literal>kernel</literal>. When true,
          enables the privacy extensions and prefers temporary addresses over public addresses. When
          <literal>prefer-public</literal>, enables the privacy extensions, but prefers public
          addresses over temporary addresses. When false, the privacy extensions remain disabled. When
          <literal>kernel</literal>, the kernel's default setting will be left in place. Defaults to
          <literal>no</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv6AcceptRA=</varname></term>
        <listitem>
          <para>Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the
          interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they
          may trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or
          if no routers are found on the link. The default is to disable RA reception for bridge
          devices or when IP forwarding is enabled, and to enable it otherwise. Cannot be enabled on
          devices aggregated in a bond device or when link-local addressing is disabled.</para>

          <para>Further settings for the IPv6 RA support may be configured in the [IPv6AcceptRA]
          section, see below.</para>

          <para>Also see
          <ulink url="https://docs.kernel.org/networking/ip-sysctl.html">IP Sysctl</ulink>
          in the kernel documentation regarding <literal>accept_ra</literal>, but note that systemd's
          setting of <constant>1</constant> (i.e. true) corresponds to kernel's setting of
          <constant>2</constant>.</para>

          <para>Note that kernel's implementation of the IPv6 RA protocol is always disabled,
          regardless of this setting. If this option is enabled, a userspace implementation of the IPv6
          RA protocol is used, and the kernel's own implementation remains disabled, since
          <command>systemd-networkd</command> needs to know all details supplied in the advertisements,
          and these are not available from the kernel if the kernel's own implementation is used.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv6DuplicateAddressDetection=</varname></term>
        <listitem>
          <para>Configures the amount of IPv6 Duplicate Address Detection (DAD) probes to send. When
          unset, the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv6HopLimit=</varname></term>
        <listitem>
          <para>Configures IPv6 Hop Limit. For each router that forwards the packet, the hop limit is
          decremented by 1. When the hop limit field reaches zero, the packet is discarded. When unset,
          the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv4AcceptLocal=</varname></term>
        <listitem>
          <para>Takes a boolean. Accept packets with local source addresses. In combination with
          suitable routing, this can be used to direct packets between two local interfaces over the
          wire and have them accepted properly. When unset, the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv4RouteLocalnet=</varname></term>
        <listitem>
          <para>Takes a boolean. When true, the kernel does not consider loopback addresses as martian
          source or destination while routing. This enables the use of 127.0.0.0/8 for local routing
          purposes. When unset, the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv4ProxyARP=</varname></term>
        <listitem>
          <para>Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one
          host, usually a router, answers ARP requests intended for another machine. By "faking" its
          identity, the router accepts responsibility for routing packets to the "real" destination.
          See <ulink url="https://tools.ietf.org/html/rfc1027">RFC 1027</ulink>. When unset, the
          kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv6ProxyNDP=</varname></term>
        <listitem>
          <para>Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery Protocol)
          is a technique for IPv6 to allow routing of addresses to a different destination when peers
          expect them to be present on a certain physical link. In this case a router answers Neighbour
          Advertisement messages intended for another machine by offering its own MAC address as
          destination. Unlike proxy ARP for IPv4, it is not enabled globally, but will only send
          Neighbour Advertisement messages for addresses in the IPv6 neighbor proxy table, which can
          also be shown by <command>ip -6 neighbour show proxy</command>. systemd-networkd will control
          the per-interface `proxy_ndp` switch for each configured interface depending on this option.
          When unset, the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv6ProxyNDPAddress=</varname></term>
        <listitem>
          <para>An IPv6 address, for which Neighbour Advertisement messages will be proxied. This
          option may be specified more than once. systemd-networkd will add the
          <varname>IPv6ProxyNDPAddress=</varname> entries to the kernel's IPv6 neighbor proxy table.
          This setting implies <varname>IPv6ProxyNDP=yes</varname> but has no effect if
          <varname>IPv6ProxyNDP=</varname> has been set to false. When unset, the kernel's default will
          be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv6SendRA=</varname></term>
        <listitem>
          <para>Whether to enable or disable Router Advertisement sending on a link. Takes a boolean
          value. When enabled, prefixes configured in [IPv6Prefix] sections and routes configured in
          the [IPv6RoutePrefix] sections are distributed as defined in the [IPv6SendRA] section. If
          <varname>DHCPPrefixDelegation=</varname> is enabled, then the delegated prefixes are also
          distributed. See <varname>DCHPPrefixDelegation=</varname> setting and the [IPv6SendRA],
          [IPv6Prefix], [IPv6RoutePrefix], and [DHCPPrefixDelegation] sections for more configuration
          options.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DHCPPrefixDelegation=</varname></term>
        <listitem>
          <para>Takes a boolean value. When enabled, requests subnet prefixes on another link via the DHCPv6
          protocol or via the 6RD option in the DHCPv4 protocol. An address within each delegated prefix will
          be assigned, and the prefixes will be announced through IPv6 Router Advertisement if
          <varname>IPv6SendRA=</varname> is enabled. This behaviour can be configured in the
          [DHCPPrefixDelegation] section. Defaults to disabled.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv6MTUBytes=</varname></term>
        <listitem>
          <para>Configures IPv6 maximum transmission unit (MTU). An integer greater than or equal to
          1280 bytes. When unset, the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>KeepMaster=</varname></term>
        <listitem>
          <para>Takes a boolean value. When enabled, the current master interface index will not be
          changed, and <varname>BatmanAdvanced=</varname>, <varname>Bond=</varname>,
          <varname>Bridge=</varname>, and <varname>VRF=</varname> settings are ignored. This may be
          useful when a netdev with a master interface is created by another program, e.g.
          <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
          Defaults to false.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>BatmanAdvanced=</varname></term>
        <term><varname>Bond=</varname></term>
        <term><varname>Bridge=</varname></term>
        <term><varname>VRF=</varname></term>
        <listitem>
          <para>The name of the B.A.T.M.A.N. Advanced, bond, bridge, or VRF interface to add the link
          to. See
          <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPoIB=</varname></term>
        <term><varname>IPVLAN=</varname></term>
        <term><varname>IPVTAP=</varname></term>
        <term><varname>MACsec=</varname></term>
        <term><varname>MACVLAN=</varname></term>
        <term><varname>MACVTAP=</varname></term>
        <term><varname>Tunnel=</varname></term>
        <term><varname>VLAN=</varname></term>
        <term><varname>VXLAN=</varname></term>
        <term><varname>Xfrm=</varname></term>
        <listitem>
          <para>The name of an IPoIB, IPVLAN, IPVTAP, MACsec, MACVLAN, MACVTAP, tunnel, VLAN,
          VXLAN, or Xfrm to be created on the link. See
          <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
          This option may be specified more than once.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>ActiveSlave=</varname></term>
        <listitem>
          <para>Takes a boolean. Specifies the new active slave. The <literal>ActiveSlave=</literal>
          option is only valid for following modes: <literal>active-backup</literal>,
          <literal>balance-alb</literal>, and <literal>balance-tlb</literal>. Defaults to false.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PrimarySlave=</varname></term>
        <listitem>
          <para>Takes a boolean. Specifies which slave is the primary device. The specified device will
          always be the active slave while it is available. Only when the primary is off-line will
          alternate devices be used.  This is useful when one slave is preferred over another, e.g.
          when one slave has higher throughput than another. The <literal>PrimarySlave=</literal>
          option is only valid for following modes: <literal>active-backup</literal>,
          <literal>balance-alb</literal>, and <literal>balance-tlb</literal>. Defaults to false.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>ConfigureWithoutCarrier=</varname></term>
        <listitem>
          <para>Takes a boolean. Allows networkd to configure a specific link even if it has no
          carrier. Defaults to false. If enabled, and the <varname>IgnoreCarrierLoss=</varname> setting
          is not explicitly set, then it is enabled as well.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IgnoreCarrierLoss=</varname></term>
        <listitem>
          <para>Takes a boolean or a timespan. When true, <command>systemd-networkd</command> retains
          both the static and dynamic configuration of the interface even if its carrier is lost. When
          false, <command>systemd-networkd</command> drops both the static and dynamic configuration of
          the interface. When a timespan is specified, <command>systemd-networkd</command> waits for
          the specified timespan, and ignores the carrier loss if the link regain its carrier within
          the timespan. Setting 0 seconds is equivalent to <literal>no</literal>, and
          <literal>infinite</literal> is equivalent to <literal>yes</literal>.</para>

          <para>Setting a finite timespan may be useful when e.g. in the following cases:
          <itemizedlist>
            <listitem>
              <para>A wireless interface connecting to a network which has multiple access points with
              the same SSID.</para>
            </listitem>
            <listitem>
              <para>Enslaving a wireless interface to a bond interface, which may disconnect from the
              connected access point and causes its carrier to be lost.</para>
            </listitem>
            <listitem>
              <para>The driver of the interface resets when the MTU is changed.</para>
            </listitem>
          </itemizedlist>
          </para>

          <para>When <varname>Bond=</varname> is specified to a wireless interface, defaults to 3
          seconds. When the DHCPv4 client is enabled and <varname>UseMTU=</varname> in the [DHCPv4]
          section enabled, defaults to 5 seconds. Otherwise, defaults to the value specified with
          <varname>ConfigureWithoutCarrier=</varname>. When <varname>ActivationPolicy=</varname> is set
          to <literal>always-up</literal>, this is forced to <literal>yes</literal>, and ignored any
          user specified values.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>KeepConfiguration=</varname></term>
        <listitem>
          <para>Takes a boolean or one of <literal>static</literal>, <literal>dhcp-on-stop</literal>,
          <literal>dhcp</literal>. When <literal>static</literal>, <command>systemd-networkd</command>
          will not drop static addresses and routes on starting up process. When set to
          <literal>dhcp-on-stop</literal>, <command>systemd-networkd</command> will not drop addresses
          and routes on stopping the daemon. When <literal>dhcp</literal>,
          the addresses and routes provided by a DHCP server will never be dropped even if the DHCP
          lease expires. This is contrary to the DHCP specification, but may be the best choice if,
          e.g., the root filesystem relies on this connection. The setting <literal>dhcp</literal>
          implies <literal>dhcp-on-stop</literal>, and <literal>yes</literal> implies
          <literal>dhcp</literal> and <literal>static</literal>. Defaults to
          <literal>dhcp-on-stop</literal> when <command>systemd-networkd</command> is running in
          initrd, <literal>yes</literal> when the root filesystem is a network filesystem, and
          <literal>no</literal> otherwise.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[Address] Section Options</title>

    <para>An [Address] section accepts the following keys. Specify several [Address] sections to
    configure several addresses.</para>

    <variablelist class='network-directives'>
      <varlistentry>
        <term><varname>Address=</varname></term>
        <listitem>
          <para>As in the [Network] section. This setting is mandatory. Each [Address] section can
          contain one <varname>Address=</varname> setting.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Peer=</varname></term>
        <listitem>
          <para>The peer address in a point-to-point connection. Accepts the same format as the
          <varname>Address=</varname> setting.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Broadcast=</varname></term>
        <listitem>
          <para>Takes an IPv4 address or boolean value. The address must be in the format described in
          <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
          If set to true, then the IPv4 broadcast address will be derived from the
          <varname>Address=</varname> setting. If set to false, then the broadcast address will not be
          set. Defaults to true, except for wireguard interfaces, where it default to false.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Label=</varname></term>
        <listitem>
          <para>Specifies the label for the IPv4 address. The label must be a 7-bit ASCII string with
          a length of 1…15 characters. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PreferredLifetime=</varname></term>
        <listitem>
          <para>Allows the default "preferred lifetime" of the address to be overridden. Only three
          settings are accepted: <literal>forever</literal>, <literal>infinity</literal>, which is the
          default and means that the address never expires, and <literal>0</literal>, which means that
          the address is considered immediately "expired" and will not be used, unless explicitly
          requested. A setting of <option>PreferredLifetime=0</option> is useful for addresses which
          are added to be used only by a specific application, which is then configured to use them
          explicitly.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Scope=</varname></term>
        <listitem>
          <para>The scope of the address, which can be <literal>global</literal> (valid everywhere on
          the network, even through a gateway), <literal>link</literal> (only valid on this device,
          will not traverse a gateway) or <literal>host</literal> (only valid within the device itself,
          e.g. 127.0.0.1) or an integer in the range 0…255. Defaults to <literal>global</literal>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouteMetric=</varname></term>
        <listitem>
          <para>The metric of the prefix route, which is pointing to the subnet of the configured IP
          address, taking the configured prefix length into account. Takes an unsigned integer in the
          range 0…4294967295. When unset or set to 0, the kernel's default value is used. This
          setting will be ignored when <varname>AddPrefixRoute=</varname> is false.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>HomeAddress=</varname></term>
        <listitem>
          <para>Takes a boolean. Designates this address the "home address" as defined in
          <ulink url="https://tools.ietf.org/html/rfc6275">RFC 6275</ulink>. Supported only on IPv6.
          Defaults to false.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DuplicateAddressDetection=</varname></term>
        <listitem>
          <para>Takes one of <literal>ipv4</literal>, <literal>ipv6</literal>, <literal>both</literal>,
          or <literal>none</literal>. When <literal>ipv4</literal>, performs IPv4 Address Conflict
          Detection. See <ulink url="https://tools.ietf.org/html/rfc5227">RFC 5227</ulink>.
          When <literal>ipv6</literal>, performs IPv6 Duplicate Address Detection. See
          <ulink url="https://tools.ietf.org/html/rfc4862">RFC 4862</ulink>. Defaults to
          <literal>ipv4</literal> for IPv4 link-local addresses, <literal>ipv6</literal> for IPv6
          addresses, and <literal>none</literal> otherwise.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>ManageTemporaryAddress=</varname></term>
        <listitem>
          <para>Takes a boolean. If true the kernel manage temporary addresses created from this one as
          template on behalf of Privacy Extensions
          <ulink url="https://tools.ietf.org/html/rfc3041">RFC 3041</ulink>. For this to become active,
          the use_tempaddr sysctl setting has to be set to a value greater than zero. The given address
          needs to have a prefix length of 64. This flag allows using privacy extensions in a manually
          configured network, just like if stateless auto-configuration was active. Defaults to false.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>AddPrefixRoute=</varname></term>
        <listitem>
          <para>Takes a boolean. When true, the prefix route for the address is automatically added.
          Defaults to true.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>AutoJoin=</varname></term>
        <listitem>
          <para>Takes a boolean. Joining multicast group on ethernet level via
          <command>ip maddr</command> command would not work if we have an Ethernet switch that does
          IGMP snooping since the switch would not replicate multicast packets on  ports that did not
          have IGMP reports for the multicast addresses. Linux vxlan interfaces created via
          <command>ip link add vxlan</command> or networkd's netdev kind vxlan have the group option
          that enables them to do the required join. By extending <command>ip address</command> command
          with option <literal>autojoin</literal> we can get similar functionality for openvswitch (OVS)
          vxlan interfaces as well as other tunneling mechanisms that need to receive multicast traffic.
          Defaults to <literal>no</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>NetLabel=</varname><replaceable>label</replaceable></term>
        <listitem>

          <para>This setting provides a method for integrating static and dynamic network configuration into
          Linux <ulink url="https://docs.kernel.org/netlabel/index.html">NetLabel</ulink> subsystem rules,
          used by <ulink url="https://en.wikipedia.org/wiki/Linux_Security_Modules">Linux Security Modules
          (LSMs)</ulink> for network access control. The label, with suitable LSM rules, can be used to
          control connectivity of (for example) a service with peers in the local network. At least with
          SELinux, only the ingress can be controlled but not egress. The benefit of using this setting is
          that it may be possible to apply interface independent part of NetLabel configuration at very early
          stage of system boot sequence, at the time when the network interfaces are not available yet, with
          <citerefentry
          project='man-pages'><refentrytitle>netlabelctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
          and the per-interface configuration with <command>systemd-networkd</command> once the interfaces
          appear later. Currently this feature is only implemented for SELinux.</para>

          <para>The option expects a single NetLabel label. The label must conform to lexical restrictions of
          LSM labels. When an interface is configured with IP addresses, the addresses and subnetwork masks
          will be appended to the <ulink
          url="https://github.com/SELinuxProject/selinux-notebook/blob/main/src/network_support.md">NetLabel
          Fallback Peer Labeling</ulink> rules. They will be removed when the interface is
          deconfigured. Failures to manage the labels will be ignored.</para>

          <para>Warning: Once labeling is enabled for network traffic, a lot of LSM access control points in
          Linux networking stack go from dormant to active. Care should be taken to avoid getting into a
          situation where for example remote connectivity is broken, when the security policy hasn't been
          updated to consider LSM per-packet access controls and no rules would allow any network
          traffic. Also note that additional configuration with <citerefentry
          project='man-pages'><refentrytitle>netlabelctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>
          is needed.</para>

          <para>Example:
          <programlisting>[Address]
NetLabel=system_u:object_r:localnet_peer_t:s0</programlisting>

          With the example rules applying for interface <literal>eth0</literal>, when the interface is
          configured with an IPv4 address of 10.0.0.123/8, <command>systemd-networkd</command> performs the
          equivalent of <command>netlabelctl</command> operation

          <programlisting>netlabelctl unlbl add interface eth0 address:10.0.0.0/8 label:system_u:object_r:localnet_peer_t:s0</programlisting>

          and the reverse operation when the IPv4 address is deconfigured. The configuration can be used with
          LSM rules; in case of SELinux to allow a SELinux domain to receive data from objects of SELinux
          <literal>peer</literal> class. For example:

          <programlisting>type localnet_peer_t;
allow my_server_t localnet_peer_t:peer recv;</programlisting>

          The effect of the above configuration and rules (in absence of other rules as may be the case) is
          to only allow <literal>my_server_t</literal> (and nothing else) to receive data from local subnet
          10.0.0.0/8 of interface <literal>eth0</literal>.
          </para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[Neighbor] Section Options</title>

    <para>A [Neighbor] section accepts the following keys. The neighbor section adds a permanent,
    static entry to the neighbor table (IPv6) or ARP table (IPv4) for the given hardware address on the
    links matched for the network. Specify several [Neighbor] sections to configure several static
    neighbors.</para>

    <variablelist class='network-directives'>
      <varlistentry>
        <term><varname>Address=</varname></term>
        <listitem>
          <para>The IP address of the neighbor.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>LinkLayerAddress=</varname></term>
        <listitem>
          <para>The link layer address (MAC address or IP address) of the neighbor.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[IPv6AddressLabel] Section Options</title>

    <para>An [IPv6AddressLabel] section accepts the following keys. Specify several [IPv6AddressLabel]
    sections to configure several address labels. IPv6 address labels are used for address selection.
    See <ulink url="https://tools.ietf.org/html/rfc3484">RFC 3484</ulink>. Precedence is managed by
    userspace, and only the label itself is stored in the kernel.</para>

    <variablelist class='network-directives'>
      <varlistentry>
        <term><varname>Label=</varname></term>
        <listitem>
          <para>The label for the prefix, an unsigned integer in the range 0…4294967294. 0xffffffff is
          reserved. This setting is mandatory.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Prefix=</varname></term>
        <listitem>
          <para>IPv6 prefix is an address with a prefix length, separated by a slash
          <literal>/</literal> character. This setting is mandatory. </para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[RoutingPolicyRule] Section Options</title>

    <para>An [RoutingPolicyRule] section accepts the following settings. Specify several
    [RoutingPolicyRule] sections to configure several rules.</para>

    <variablelist class='network-directives'>
      <varlistentry>
        <term><varname>TypeOfService=</varname></term>
        <listitem>
          <para>Takes a number between 0 and 255 that specifies the type of service to match.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>From=</varname></term>
        <listitem>
          <para>Specifies the source address prefix to match. Possibly followed by a slash and the
          prefix length.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>To=</varname></term>
        <listitem>
          <para>Specifies the destination address prefix to match. Possibly followed by a slash and the
          prefix length.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>FirewallMark=</varname></term>
        <listitem>
          <para>Specifies the iptables firewall mark value to match (a number in the range
          1…4294967295). Optionally, the firewall mask (also a number between 1…4294967295) can be
          suffixed with a slash (<literal>/</literal>), e.g., <literal>7/255</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Table=</varname></term>
        <listitem>
          <para>Specifies the routing table identifier to look up if the rule selector matches. Takes
          one of predefined names <literal>default</literal>, <literal>main</literal>, and
          <literal>local</literal>, and names defined in <varname>RouteTable=</varname> in
          <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
          or a number between 1 and 4294967295. Defaults to <literal>main</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Priority=</varname></term>
        <listitem>
          <para>Specifies the priority of this rule. <varname>Priority=</varname> is an integer in the
          range 0…4294967295. Higher number means lower priority, and rules get processed in order of
          increasing number. Defaults to unset, and the kernel will pick a value dynamically.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IncomingInterface=</varname></term>
        <listitem>
          <para>Specifies incoming device to match. If the interface is loopback, the rule only matches
          packets originating from this host.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>OutgoingInterface=</varname></term>
        <listitem>
          <para>Specifies the outgoing device to match. The outgoing interface is only available for
          packets originating from local sockets that are bound to a device.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SourcePort=</varname></term>
        <listitem>
          <para>Specifies the source IP port or IP port range match in forwarding information base
          (FIB) rules. A port range is specified by the lower and upper port separated by a dash.
          Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DestinationPort=</varname></term>
        <listitem>
          <para>Specifies the destination IP port or IP port range match in forwarding information base
          (FIB) rules. A port range is specified by the lower and upper port separated by a dash.
          Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPProtocol=</varname></term>
        <listitem>
          <para>Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP
          protocol name such as <literal>tcp</literal>, <literal>udp</literal> or
          <literal>sctp</literal>, or IP protocol number such as <literal>6</literal> for
          <literal>tcp</literal> or <literal>17</literal> for <literal>udp</literal>. Defaults to unset.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>InvertRule=</varname></term>
        <listitem>
          <para>A boolean. Specifies whether the rule is to be inverted. Defaults to false.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Family=</varname></term>
        <listitem>
          <para>Takes a special value <literal>ipv4</literal>, <literal>ipv6</literal>, or
          <literal>both</literal>. By default, the address family is determined by the address
          specified in <varname>To=</varname> or <varname>From=</varname>. If neither
          <varname>To=</varname> nor <varname>From=</varname> are specified, then defaults to
          <literal>ipv4</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>User=</varname></term>
        <listitem>
          <para>Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to
          unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SuppressPrefixLength=</varname></term>
        <listitem>
          <para>Takes a number <replaceable>N</replaceable> in the range 0…128 and rejects routing
          decisions that have a prefix length of <replaceable>N</replaceable> or less. Defaults to
          unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SuppressInterfaceGroup=</varname></term>
        <listitem>
          <para>Takes an integer in the range 0…2147483647 and rejects routing decisions that have
          an interface with the same group id. It has the same meaning as
          <option>suppress_ifgroup</option> in <command>ip rule</command>. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Type=</varname></term>
        <listitem>
          <para>Specifies Routing Policy Database (RPDB) rule type. Takes one of
          <literal>blackhole</literal>, <literal>unreachable</literal> or <literal>prohibit</literal>.
          </para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[NextHop] Section Options</title>

    <para>The [NextHop] section is used to manipulate entries in the kernel's "nexthop" tables. The
    [NextHop] section accepts the following settings. Specify several [NextHop] sections to configure
    several hops.</para>

    <variablelist class='network-directives'>
      <varlistentry>
        <term><varname>Id=</varname></term>
        <listitem>
          <para>The id of the next hop. Takes an integer in the range 1…4294967295. If unspecified,
          then automatically chosen by kernel.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Gateway=</varname></term>
        <listitem>
          <para>As in the [Network] section.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Family=</varname></term>
        <listitem>
          <para>Takes one of the special values <literal>ipv4</literal> or <literal>ipv6</literal>.
          By default, the family is determined by the address specified in
          <varname>Gateway=</varname>. If <varname>Gateway=</varname> is not specified, then defaults
          to <literal>ipv4</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>OnLink=</varname></term>
        <listitem>
          <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
          reachable directly by the current machine (i.e., attached to the local network), so that we
          can insert the nexthop in the kernel table without it being complained about. Defaults to
          <literal>no</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Blackhole=</varname></term>
        <listitem>
          <para>Takes a boolean. If enabled, packets to the corresponding routes are discarded
          silently, and <varname>Gateway=</varname> cannot be specified. Defaults to
          <literal>no</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Group=</varname></term>
        <listitem>
          <para>Takes a whitespace separated list of nexthop IDs. Each ID must be in the range
          1…4294967295. Optionally, each nexthop ID can take a weight after a colon
          (<literal><replaceable>id</replaceable><optional>:<replaceable>weight</replaceable></optional></literal>).
          The weight must be in the range 1…255. If the weight is not specified, then it is assumed
          that the weight is 1. This setting cannot be specified with <varname>Gateway=</varname>,
          <varname>Family=</varname>, <varname>Blackhole=</varname>. This setting can be specified
          multiple times. If an empty string is assigned, then the all previous assignments are
          cleared. Defaults to unset.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[Route] Section Options</title>

    <para>The [Route] section accepts the following settings. Specify several [Route] sections to
    configure several routes.</para>

    <variablelist class='network-directives'>
      <varlistentry>
        <term><varname>Gateway=</varname></term>
        <listitem>
          <para>Takes the gateway address or the special values <literal>_dhcp4</literal> and
          <literal>_ipv6ra</literal>. If <literal>_dhcp4</literal> or <literal>_ipv6ra</literal> is
          set, then the gateway address provided by DHCPv4 or IPv6 RA is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>GatewayOnLink=</varname></term>
        <listitem>
          <para>Takes a boolean. If set to true, the kernel does not have to check if the gateway is
          reachable directly by the current machine (i.e., attached to the local network), so that we
          can insert the route in the kernel table without it being complained about. Defaults to
          <literal>no</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Destination=</varname></term>
        <listitem>
          <para>The destination prefix of the route. Possibly followed by a slash and the prefix
          length. If omitted, a full-length host route is assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Source=</varname></term>
        <listitem>
          <para>The source prefix of the route. Possibly followed by a slash and the prefix length. If
          omitted, a full-length host route is assumed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Metric=</varname></term>
        <listitem>
          <para>The metric of the route. Takes an unsigned integer in the range 0…4294967295. Defaults
          to unset, and the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPv6Preference=</varname></term>
        <listitem>
          <para>Specifies the route preference as defined in
          <ulink url="https://tools.ietf.org/html/rfc4191">RFC 4191</ulink> for Router Discovery
          messages. Which can be one of <literal>low</literal> the route has a lowest priority,
          <literal>medium</literal> the route has a default priority or <literal>high</literal> the
          route has a highest priority.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Scope=</varname></term>
        <listitem>
          <para>The scope of the IPv4 route, which can be <literal>global</literal>,
          <literal>site</literal>, <literal>link</literal>, <literal>host</literal>, or
          <literal>nowhere</literal>:</para>
          <itemizedlist>
            <listitem>
              <para><literal>global</literal> means the route can reach hosts more than one hop away.
              </para>
            </listitem>

            <listitem>
              <para><literal>site</literal> means an interior route in the local autonomous system.
              </para>
            </listitem>

            <listitem>
              <para><literal>link</literal> means the route can only reach hosts on the local network
              (one hop away).</para>
            </listitem>

            <listitem>
              <para><literal>host</literal> means the route will not leave the local machine (used for
              internal addresses like 127.0.0.1).</para>
            </listitem>

            <listitem>
              <para><literal>nowhere</literal> means the destination doesn't exist.</para>
            </listitem>
          </itemizedlist>

          <para>For IPv4 route, defaults to <literal>host</literal> if <varname>Type=</varname> is
          <literal>local</literal> or <literal>nat</literal>, and <literal>link</literal> if
          <varname>Type=</varname> is <literal>broadcast</literal>, <literal>multicast</literal>,
          <literal>anycast</literal>, or <literal>unicast</literal>. In other cases,
          defaults to <literal>global</literal>. The value is not used for IPv6.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PreferredSource=</varname></term>
        <listitem>
          <para>The preferred source address of the route. The address must be in the format described
          in
          <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Table=</varname></term>
        <listitem>
          <para>The table identifier for the route. Takes one of predefined names
          <literal>default</literal>, <literal>main</literal>, and <literal>local</literal>, and names
          defined in <varname>RouteTable=</varname> in
          <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
          or a number between 1 and 4294967295. The table can be retrieved using
          <command>ip route show table <replaceable>num</replaceable></command>. If unset and
          <varname>Type=</varname> is <literal>local</literal>, <literal>broadcast</literal>,
          <literal>anycast</literal>, or <literal>nat</literal>, then <literal>local</literal> is used.
          In other cases, defaults to <literal>main</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Protocol=</varname></term>
        <listitem>
          <para>The protocol identifier for the route. Takes a number between 0 and 255 or the special
          values <literal>kernel</literal>, <literal>boot</literal>, <literal>static</literal>,
          <literal>ra</literal> and <literal>dhcp</literal>. Defaults to <literal>static</literal>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Type=</varname></term>
        <listitem>
          <para>Specifies the type for the route. Takes one of <literal>unicast</literal>,
          <literal>local</literal>, <literal>broadcast</literal>, <literal>anycast</literal>,
          <literal>multicast</literal>, <literal>blackhole</literal>, <literal>unreachable</literal>,
          <literal>prohibit</literal>, <literal>throw</literal>, <literal>nat</literal>, and
          <literal>xresolve</literal>. If <literal>unicast</literal>, a regular route is defined, i.e.
          a route indicating the path to take to a destination network address. If
          <literal>blackhole</literal>, packets to the defined route are discarded silently. If
          <literal>unreachable</literal>, packets to the defined route are discarded and the ICMP
          message "Host Unreachable" is generated. If <literal>prohibit</literal>, packets to the
          defined route are discarded and the ICMP message "Communication Administratively Prohibited"
          is generated. If <literal>throw</literal>, route lookup in the current routing table will
          fail and the route selection process will return to Routing Policy Database (RPDB). Defaults
          to <literal>unicast</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>InitialCongestionWindow=</varname></term>
        <listitem>
          <para>The TCP initial congestion window is used during the start of a TCP connection.
          During the start of a TCP session, when a client requests a resource, the server's initial
          congestion window determines how many packets will be sent during the initial burst of data
          without waiting for acknowledgement. Takes a number between 1 and 1023. Note that 100 is
          considered an extremely large value for this option. When unset, the kernel's default
          (typically 10) will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>InitialAdvertisedReceiveWindow=</varname></term>
        <listitem>
          <para>The TCP initial advertised receive window is the amount of receive data (in bytes)
          that can initially be buffered at one time on a connection. The sending host can send only
          that amount of data before waiting for an acknowledgment and window update from the
          receiving host. Takes a number between 1 and 1023. Note that 100 is considered an extremely
          large value for this option. When unset, the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>QuickAck=</varname></term>
        <listitem>
          <para>Takes a boolean. When true, the TCP quick ACK mode for the route is enabled. When unset,
          the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>FastOpenNoCookie=</varname></term>
        <listitem>
          <para>Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis.
          When unset, the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>TTLPropagate=</varname></term>
        <listitem>
          <para>Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress.
          When unset, the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MTUBytes=</varname></term>
        <listitem>
          <para>The maximum transmission unit in bytes to set for the route. The usual suffixes K, M,
          G, are supported and are understood to the base of 1024.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>TCPAdvertisedMaximumSegmentSize=</varname></term>
        <listitem>
          <para>Specifies the Path MSS (in bytes) hints given on TCP layer. The usual suffixes K, M, G,
          are supported and are understood to the base of 1024. An unsigned integer in the range
          1…4294967294. When unset, the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>TCPCongestionControlAlgorithm=</varname></term>
        <listitem>
          <para>Specifies the TCP congestion control algorithm for the route. Takes a name of the algorithm,
          e.g. <literal>bbr</literal>, <literal>dctcp</literal>, or <literal>vegas</literal>. When unset,
          the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MultiPathRoute=<replaceable>address</replaceable>[@<replaceable>name</replaceable>] [<replaceable>weight</replaceable>]</varname></term>
        <listitem>
          <para>Configures multipath route. Multipath routing is the technique of using multiple
          alternative paths through a network. Takes gateway address. Optionally, takes a network
          interface name or index separated with <literal>@</literal>, and a weight in 1..256 for this
          multipath route separated with whitespace. This setting can be specified multiple times. If
          an empty string is assigned, then the all previous assignments are cleared.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>NextHop=</varname></term>
        <listitem>
          <para>Specifies the nexthop id. Takes an unsigned integer in the range 1…4294967295. If set,
          the corresponding [NextHop] section must be configured. Defaults to unset.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[DHCPv4] Section Options</title>

    <para>The [DHCPv4] section configures the DHCPv4 client, if it is enabled with the
    <varname>DHCP=</varname> setting described above:</para>

    <variablelist class='network-directives'>

      <!-- DHCP packet contents -->

      <varlistentry>
        <term><varname>SendHostname=</varname></term>
        <listitem>
          <para>When true (the default), the machine's hostname (or the value specified with
          <varname>Hostname=</varname>, described below) will be sent to the DHCP server. Note that the
          hostname must consist only of 7-bit ASCII lower-case characters and no spaces or dots, and be
          formatted as a valid DNS domain name. Otherwise, the hostname is not sent even if this option
          is true.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Hostname=</varname></term>
        <listitem>
          <para>Use this value for the hostname which is sent to the DHCP server, instead of machine's
          hostname. Note that the specified hostname must consist only of 7-bit ASCII lower-case
          characters and no spaces or dots, and be formatted as a valid DNS domain name.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MUDURL=</varname></term>
        <listitem>
          <para>When configured, the specified Manufacturer Usage Description (MUD) URL will be sent
          to the DHCPv4 server. Takes a URL of length up to 255 characters. A superficial verification
          that the string is a valid URL will be performed. DHCPv4 clients are intended to have at most
          one MUD URL associated with them. See
          <ulink url="https://tools.ietf.org/html/rfc8520">RFC 8520</ulink>.</para>

          <para>MUD is an embedded software standard defined by the IETF that allows IoT device makers
          to advertise device specifications, including the intended communication patterns for their
          device when it connects to the network. The network can then use this to author a
          context-specific access policy, so the device functions only within those parameters.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>ClientIdentifier=</varname></term>
        <listitem>
          <para>The DHCPv4 client identifier to use. Takes one of <option>mac</option>,
          <option>duid</option> or <option>duid-only</option>. If set to <option>mac</option>, the
          MAC address of the link is used. If set to <option>duid</option>, an RFC4361-compliant Client
          ID, which is the combination of IAID and DUID (see below), is used. If set to
          <option>duid-only</option>, only DUID is used, this may not be RFC compliant, but some setups
          may require to use this. Defaults to <option>duid</option>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>VendorClassIdentifier=</varname></term>
        <listitem>
          <para>The vendor class identifier used to identify vendor type and configuration.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UserClass=</varname></term>
        <listitem>
          <para>A DHCPv4 client can use UserClass option to identify the type or category of user or
          applications it represents. The information contained in this option is a string that
          represents the user class of which the client is a member. Each class sets an identifying
          string of information to be used by the DHCP service to classify clients. Takes a
          whitespace-separated list of strings.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DUIDType=</varname></term>
        <listitem>
          <para>Override the global <varname>DUIDType=</varname> setting for this network. See
          <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
          for a description of possible values.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DUIDRawData=</varname></term>
        <listitem>
          <para>Override the global <varname>DUIDRawData=</varname> setting for this network. See
          <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
          for a description of possible values.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IAID=</varname></term>
        <listitem>
          <para>The DHCP Identity Association Identifier (IAID) for the interface, a 32-bit unsigned
          integer.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Anonymize=</varname></term>
        <listitem>
          <para>Takes a boolean. When true, the options sent to the DHCP server will follow the
          <ulink url="https://tools.ietf.org/html/rfc7844">RFC 7844</ulink> (Anonymity Profiles for
          DHCP Clients) to minimize disclosure of identifying information. Defaults to false.</para>

          <para>This option should only be set to true when <varname>MACAddressPolicy=</varname> is set
          to <option>random</option> (see
          <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
          </para>

          <para>When true, <varname>SendHostname=</varname>, <varname>ClientIdentifier=</varname>,
          <varname>VendorClassIdentifier=</varname>, <varname>UserClass=</varname>,
          <varname>RequestOptions=</varname>, <varname>SendOption=</varname>,
          <varname>SendVendorOption=</varname>, and <varname>MUDURL=</varname> are ignored.</para>

          <para>With this option enabled DHCP requests will mimic those generated by Microsoft
          Windows, in order to reduce the ability to fingerprint and recognize installations. This
          means DHCP request sizes will grow and lease data will be more comprehensive than normally,
          though most of the requested data is not actually used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RequestOptions=</varname></term>
        <listitem>
          <para>Sets request options to be sent to the server in the DHCPv4 request options list. A
          whitespace-separated list of integers in the range 1…254. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SendOption=</varname></term>
        <listitem>
          <para>Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data
          type and data separated with a colon
          (<literal><replaceable>option</replaceable>:<replaceable>type</replaceable>:<replaceable>value</replaceable></literal>).
          The option number must be an integer in the range 1…254. The type takes one of
          <literal>uint8</literal>, <literal>uint16</literal>, <literal>uint32</literal>,
          <literal>ipv4address</literal>, or <literal>string</literal>. Special characters in the data
          string may be escaped using
          <ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
          escapes</ulink>. This setting can be specified multiple times. If an empty string is
          specified, then all options specified earlier are cleared. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SendVendorOption=</varname></term>
        <listitem>
          <para>Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data
          type and data separated with a colon
          (<literal><replaceable>option</replaceable>:<replaceable>type</replaceable>:<replaceable>value</replaceable></literal>).
          The option number must be an integer in the range 1…254. The type takes one of
          <literal>uint8</literal>, <literal>uint16</literal>, <literal>uint32</literal>,
          <literal>ipv4address</literal>, or <literal>string</literal>. Special characters in the data
          string may be escaped using
          <ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
          escapes</ulink>. This setting can be specified multiple times. If an empty string is specified,
          then all options specified earlier are cleared. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IPServiceType=</varname></term>
        <listitem>
          <para>Takes one of the special values <literal>none</literal>, <literal>CS6</literal>, or
          <literal>CS4</literal>. When <literal>none</literal> no IP service type is set to the packet
          sent from the DHCPv4 client. When <literal>CS6</literal> (network control) or
          <literal>CS4</literal> (realtime), the corresponding service type will be set. Defaults to
          <literal>CS6</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SocketPriority=</varname></term>
        <listitem>
          <para>The Linux socket option <constant>SO_PRIORITY</constant> applied to the raw IP socket used for
          initial DHCPv4 messages. Unset by default. Usual values range from 0 to 6.
          More details about <constant>SO_PRIORITY</constant> socket option in
          <citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
          Can be used in conjunction with [VLAN] section <varname>EgressQOSMaps=</varname> setting of .netdev
          file to set the 802.1Q VLAN ethernet tagged header priority, see
          <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <!-- How to use the DHCP lease -->

      <varlistentry>
        <term><varname>Label=</varname></term>
        <listitem>
          <para>Specifies the label for the IPv4 address received from the DHCP server. The label must
          be a 7-bit ASCII string with a length of 1…15 characters. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseDNS=</varname></term>
        <listitem>
          <para>When true (the default), the DNS servers received from the DHCP server will be used.
          </para>

          <para>This corresponds to the <option>nameserver</option> option in
          <citerefentry project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RoutesToDNS=</varname></term>
        <listitem>
          <para>When true, the routes to the DNS servers received from the DHCP server will be
          configured. When <varname>UseDNS=</varname> is disabled, this setting is ignored. Defaults to
          true.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseNTP=</varname></term>
        <listitem>
          <para>When true (the default), the NTP servers received from the DHCP server will be used by
          <filename>systemd-timesyncd.service</filename>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RoutesToNTP=</varname></term>
        <listitem>
          <para>When true, the routes to the NTP servers received from the DHCP server will be
          configured. When <varname>UseNTP=</varname> is disabled, this setting is ignored. Defaults to
          true.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseSIP=</varname></term>
        <listitem>
          <para>When true (the default), the SIP servers received from the DHCP server will be collected
          and made available to client programs.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseMTU=</varname></term>
        <listitem>
          <para>When true, the interface maximum transmission unit from the DHCP server will be used on
          the current link. If <varname>MTUBytes=</varname> is set, then this setting is ignored.
          Defaults to false.</para>

          <para>Note, some drivers will reset the interfaces if the MTU is changed. For such
          interfaces, please try to use <varname>IgnoreCarrierLoss=</varname> with a short timespan,
          e.g. <literal>3 seconds</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseHostname=</varname></term>
        <listitem>
          <para>When true (the default), the hostname received from the DHCP server will be set as the
          transient hostname of the system.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseDomains=</varname></term>
        <listitem>
          <para>Takes a boolean, or the special value <option>route</option>. When true, the domain name
          received from the DHCP server will be used as DNS search domain over this link, similarly to the
          effect of the <option>Domains=</option> setting. If set to <option>route</option>, the domain name
          received from the DHCP server will be used for routing DNS queries only, but not for searching,
          similarly to the effect of the <option>Domains=</option> setting when the argument is prefixed with
          <literal>~</literal>. Defaults to false.</para>

          <para>It is recommended to enable this option only on trusted networks, as setting this
          affects resolution of all hostnames, in particular of single-label names. It is generally
          safer to use the supplied domain only as routing domain, rather than as search domain, in
          order to not have it affect local resolution of single-label names.</para>

          <para>When set to true, this setting corresponds to the <option>domain</option> option in
          <citerefentry project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseRoutes=</varname></term>
        <listitem>
          <para>When true (the default), the static routes will be requested from the DHCP server and
          added to the routing table with a metric of 1024, and a scope of <option>global</option>,
          <option>link</option> or <option>host</option>, depending on the route's destination and
          gateway. If the destination is on the local host, e.g., 127.x.x.x, or the same as the link's
          own address, the scope will be set to <option>host</option>. Otherwise if the gateway is null
          (a direct route), a <option>link</option> scope will be used. For anything else, scope
          defaults to <option>global</option>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouteMetric=</varname></term>
        <listitem>
          <para>Set the routing metric for routes specified by the DHCP server (including the prefix
          route added for the specified prefix). Takes an unsigned integer in the range 0…4294967295.
          Defaults to 1024.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouteTable=<replaceable>num</replaceable></varname></term>
        <listitem>
          <para>The table identifier for DHCP routes. Takes one of predefined names
          <literal>default</literal>, <literal>main</literal>, and <literal>local</literal>, and names
          defined in <varname>RouteTable=</varname> in
          <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
          or a number between 1…4294967295.</para>

          <para>When used in combination with <varname>VRF=</varname>, the VRF's routing table is
          used when this parameter is not specified.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouteMTUBytes=</varname></term>
        <listitem>
          <para>Specifies the MTU for the DHCP routes. Please see the [Route] section for further
          details.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>QuickAck=</varname></term>
        <listitem>
          <para>Takes a boolean. When true, the TCP quick ACK mode is enabled for the routes configured by
          the acquired DHCPv4 lease. When unset, the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseGateway=</varname></term>
        <listitem>
          <para>When true, the gateway will be requested from the DHCP server and added to the routing
          table with a metric of 1024, and a scope of <option>link</option>. When unset, the value
          specified with <varname>UseRoutes=</varname> is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseTimezone=</varname></term>
        <listitem><para>When true, the timezone received from the DHCP server will be set as timezone
        of the local system. Defaults to false.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Use6RD=</varname></term>
        <listitem>
          <para>When true, subnets of the received IPv6 prefix are assigned to downstream interfaces
          which enables <varname>DHCPPrefixDelegation=</varname>. See also
          <varname>DHCPPrefixDelegation=</varname> in the [Network] section, the [DHCPPrefixDelegation]
          section, and <ulink url="https://tools.ietf.org/html/rfc5969">RFC 5969</ulink>. Defaults to
          false.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>FallbackLeaseLifetimeSec=</varname></term>
        <listitem>
          <para>Allows one to set DHCPv4 lease lifetime when DHCPv4 server does not send the lease
          lifetime. Takes one of <literal>forever</literal> or <literal>infinity</literal>. If
          specified, the acquired address never expires. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <!-- How to communicate with the server -->

      <varlistentry>
        <term><varname>RequestBroadcast=</varname></term>
        <listitem>
          <para>Request the server to use broadcast messages before the IP address has been configured.
          This is necessary for devices that cannot receive RAW packets, or that cannot receive packets
          at all before an IP address has been configured. On the other hand, this must not be enabled
          on networks where broadcasts are filtered out.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MaxAttempts=</varname></term>
        <listitem>
          <para>Specifies how many times the DHCPv4 client configuration should be attempted. Takes a
          number or <literal>infinity</literal>. Defaults to <literal>infinity</literal>. Note that the
          time between retries is increased exponentially, up to approximately one per minute, so the
          network will not be overloaded even if this number is high. The default is suitable in most
          circumstances.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>ListenPort=</varname></term>
        <listitem>
          <para>Set the port from which the DHCP client packets originate.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DenyList=</varname></term>
        <listitem>
          <para>A whitespace-separated list of IPv4 addresses. Each address can optionally take a
          prefix length after <literal>/</literal>. DHCP offers from servers in the list are rejected.
          Note that if <varname>AllowList=</varname> is configured then <varname>DenyList=</varname> is
          ignored.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>AllowList=</varname></term>
        <listitem>
          <para>A whitespace-separated list of IPv4 addresses. Each address can optionally take a
          prefix length after <literal>/</literal>. DHCP offers from servers in the list are accepted.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SendRelease=</varname></term>
        <listitem>
          <para>When true, the DHCPv4 client sends a DHCP release packet when it stops. Defaults to
          true.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SendDecline=</varname></term>
        <listitem>
          <para>A boolean. When true, <command>systemd-networkd</command> performs IPv4 Duplicate
          Address Detection to the acquired address by the DHCPv4 client. If duplicate is detected,
          the DHCPv4 client rejects the address by sending a <constant>DHCPDECLINE</constant> packet to
          the DHCP server, and tries to obtain an IP address again. See
          <ulink url="https://tools.ietf.org/html/rfc5227">RFC 5227</ulink>. Defaults to false.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>NetLabel=</varname></term>
        <listitem>
          <para>This applies the NetLabel for the addresses received with DHCP, like
          <varname>NetLabel=</varname> in [Address] section applies it to statically configured
          addresses. See <varname>NetLabel=</varname> in [Address] section for more details.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[DHCPv6] Section Options</title>

    <para>The [DHCPv6] section configures the DHCPv6 client, if it is enabled with the
    <varname>DHCP=</varname> setting described above, or invoked by the IPv6 Router Advertisement:
    </para>

    <variablelist class='network-directives'>

      <!-- DHCP packet contents -->

      <varlistentry>
        <term><varname>MUDURL=</varname></term>
        <term><varname>IAID=</varname></term>
        <term><varname>DUIDType=</varname></term>
        <term><varname>DUIDRawData=</varname></term>
        <term><varname>RequestOptions=</varname></term>
        <listitem>
          <para>As in the [DHCPv4] section.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SendOption=</varname></term>
        <listitem>
          <para>As in the [DHCPv4] section, however because DHCPv6 uses 16-bit fields to store option
          numbers, the option number is an integer in the range 1…65536.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SendVendorOption=</varname></term>
        <listitem>
          <para>Send an arbitrary vendor option in the DHCPv6 request. Takes an enterprise identifier,
          DHCP option number, data type, and data separated with a colon
          (<literal><replaceable>enterprise identifier</replaceable>:<replaceable>option</replaceable>:<replaceable>type</replaceable>:<replaceable>value</replaceable></literal>).
          Enterprise identifier is an unsigned integer in the range 1…4294967294. The option number
          must be an integer in the range 1…254. Data type takes one of <literal>uint8</literal>,
          <literal>uint16</literal>, <literal>uint32</literal>, <literal>ipv4address</literal>,
          <literal>ipv6address</literal>, or <literal>string</literal>. Special characters in the data
          string may be escaped using
          <ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
          escapes</ulink>. This setting can be specified multiple times. If an empty string is
          specified, then all options specified earlier are cleared. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UserClass=</varname></term>
        <listitem>
          <para>A DHCPv6 client can use User Class option to identify the type or category of user or
          applications it represents. The information contained in this option is a string that
          represents the user class of which the client is a member. Each class sets an identifying
          string of information to be used by the DHCP service to classify clients. Special characters
          in the data string may be escaped using
          <ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
          escapes</ulink>. This setting can be specified multiple times. If an empty string is
          specified, then all options specified earlier are cleared. Takes a whitespace-separated list
          of strings. Note that currently <constant>NUL</constant> bytes are not allowed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>VendorClass=</varname></term>
        <listitem>
          <para>A DHCPv6 client can use VendorClass option to identify the vendor that manufactured the
          hardware on which the client is running. The information contained in the data area of this
          option is contained in one or more opaque fields that identify details of the hardware
          configuration. Takes a whitespace-separated list of strings.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PrefixDelegationHint=</varname></term>
        <listitem>
          <para>Takes an IPv6 address with prefix length in the same format as the
          <varname>Address=</varname> in the [Network] section. The DHCPv6 client will include a prefix
          hint in the DHCPv6 solicitation sent to the server. The prefix length must be in the range
          1…128. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RapidCommit=</varname></term>
        <listitem>
          <para>Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server
          through a rapid two-message exchange (solicit and reply). When the rapid commit option is set by
          both the DHCPv6 client and the DHCPv6 server, the two-message exchange is used. Otherwise, the
          four-message exchange (solicit, advertise, request, and reply) is used. The two-message exchange
          provides faster client configuration. See
          <ulink url="https://tools.ietf.org/html/rfc3315#section-17.2.1">RFC 3315</ulink> for details.
          Defaults to true, and the two-message exchange will be used if the server support it.</para>
        </listitem>
      </varlistentry>

      <!-- How to use the DHCP lease -->

      <varlistentry>
        <term><varname>UseAddress=</varname></term>
        <listitem>
          <para>When true (the default), the IP addresses provided by the DHCPv6 server will be
          assigned.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseDelegatedPrefix=</varname></term>
        <listitem>
          <para>When true (the default), the client will request the DHCPv6 server to delegate
          prefixes. If the server provides prefixes to be delegated, then subnets of the prefixes are
          assigned to the interfaces that have <varname>DHCPPrefixDelegation=yes</varname>.
          See also the <varname>DHCPPrefixDelegation=</varname> setting in the [Network] section,
          settings in the [DHCPPrefixDelegation] section, and
          <ulink url="https://www.rfc-editor.org/rfc/rfc8415.html#section-6.3">RFC 8415</ulink>.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseDNS=</varname></term>
        <term><varname>UseNTP=</varname></term>
        <term><varname>UseHostname=</varname></term>
        <term><varname>UseDomains=</varname></term>
        <term><varname>NetLabel=</varname></term>
        <term><varname>SendRelease=</varname></term>
        <listitem>
          <para>As in the [DHCPv4] section.</para>
        </listitem>
      </varlistentry>

      <!-- How to communicate with the server -->

      <varlistentry>
        <term><varname>WithoutRA=</varname></term>
        <listitem>
          <para>Allows DHCPv6 client to start without router advertisements's
          <literal>managed</literal> or <literal>other configuration</literal> flag. Takes one of
          <literal>no</literal>, <literal>solicit</literal>, or
          <literal>information-request</literal>. If this is not specified,
          <literal>solicit</literal> is used when <varname>DHCPPrefixDelegation=</varname> is enabled
          and <varname>UplinkInterface=:self</varname> is specified in the [DHCPPrefixDelegation]
          section. Otherwise, defaults to <literal>no</literal>, and the DHCPv6 client will be started
          when an RA is received. See also the <varname>DHCPv6Client=</varname> setting in the
          [IPv6AcceptRA] section.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[DHCPPrefixDelegation] Section Options</title>
    <para>The [DHCPPrefixDelegation] section configures subnet prefixes of the delegated prefixes
    acquired by a DHCPv6 client or by a DHCPv4 client through the 6RD option on another interface.
    The settings in this section are used only when the <varname>DHCPPrefixDelegation=</varname>
    setting in the [Network] section is enabled.</para>

    <variablelist class='network-directives'>
      <varlistentry>
        <term><varname>UplinkInterface=</varname></term>
        <listitem>
          <para>Specifies the name or the index of the uplink interface, or one of the special values
          <literal>:self</literal> and <literal>:auto</literal>. When <literal>:self</literal>, the
          interface itself is considered the uplink interface, and
          <varname>WithoutRA=solicit</varname> is implied if the setting is not explicitly specified.
          When <literal>:auto</literal>, the first link which acquired prefixes to be delegated from
          the DHCPv6 or DHCPv4 server is selected. Defaults to <literal>:auto</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SubnetId=</varname></term>
        <listitem>
          <para>Configure a specific subnet ID on the interface from a (previously) received prefix
          delegation. You can either set "auto" (the default) or a specific subnet ID (as defined in
          <ulink url="https://tools.ietf.org/html/rfc4291#section-2.5.4">RFC 4291</ulink>, section
          2.5.4), in which case the allowed value is hexadecimal, from 0 to 0x7fffffffffffffff
          inclusive.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Announce=</varname></term>
        <listitem>
          <para>Takes a boolean. When enabled, and <varname>IPv6SendRA=</varname> in [Network] section
          is enabled, the delegated prefixes are distributed through the IPv6 Router Advertisement.
          This setting will be ignored when the <varname>DHCPPrefixDelegation=</varname> setting is
          enabled on the upstream interface. Defaults to yes.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Assign=</varname></term>
        <listitem>
          <para>Takes a boolean. Specifies whether to add an address from the delegated prefixes which
          are received from the WAN interface by the DHCPv6 Prefix Delegation. When true (on LAN
          interface), the EUI-64 algorithm will be used by default to form an interface identifier from
          the delegated prefixes. See also <varname>Token=</varname> setting below. Defaults to yes.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Token=</varname></term>
        <listitem>
          <para>Specifies an optional address generation mode for assigning an address in each
          delegated prefix. This accepts the same syntax as <varname>Token=</varname> in the
          [IPv6AcceptRA] section. If <varname>Assign=</varname> is set to false, then this setting will
          be ignored. Defaults to unset, which means the EUI-64 algorithm will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>ManageTemporaryAddress=</varname></term>
        <listitem>
          <para>As in the [Address] section, but defaults to true.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouteMetric=</varname></term>
        <listitem>
          <para>The metric of the route to the delegated prefix subnet. Takes an unsigned integer in
          the range 0…4294967295. When set to 0, the kernel's default value is used. Defaults to 256.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>NetLabel=</varname></term>
        <listitem>
          <para>This applies the NetLabel for the addresses received with DHCP, like
          <varname>NetLabel=</varname> in [Address] section applies it to statically configured
          addresses. See <varname>NetLabel=</varname> in [Address] section for more details.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[IPv6AcceptRA] Section Options</title>
    <para>The [IPv6AcceptRA] section configures the IPv6 Router Advertisement (RA) client, if it is enabled
    with the <varname>IPv6AcceptRA=</varname> setting described above:</para>

    <variablelist class='network-directives'>
      <varlistentry>
        <term><varname>Token=</varname></term>
        <listitem>
          <para>Specifies an optional address generation mode for the Stateless Address
          Autoconfiguration (SLAAC). The following values are supported:</para>

          <variablelist>
            <varlistentry>
              <term><option>eui64</option></term>
              <listitem>
                <para>
                  The EUI-64 algorithm will be used to generate an address for that prefix. Only
                  supported by Ethernet or InfiniBand interfaces.
                </para>
              </listitem>
            </varlistentry>
            <varlistentry>
              <term><option>static:<replaceable>ADDRESS</replaceable></option></term>
              <listitem>
                <para>
                  An IPv6 address must be specified after a colon (<literal>:</literal>), and the
                  lower bits of the supplied address are combined with the upper bits of a prefix
                  received in a Router Advertisement (RA) message to form a complete address. Note
                  that if multiple prefixes are received in an RA message, or in multiple RA messages,
                  addresses will be formed from each of them using the supplied address. This mode
                  implements SLAAC but uses a static interface identifier instead of an identifier
                  generated by using the EUI-64 algorithm. Because the interface identifier is static,
                  if Duplicate Address Detection detects that the computed address is a duplicate
                  (in use by another node on the link), then this mode will fail to provide an address
                  for that prefix. If an IPv6 address without mode is specified, then
                  <literal>static</literal> mode is assumed.
                </para>
              </listitem>
            </varlistentry>
            <varlistentry>
              <term><option>prefixstable[:<replaceable>ADDRESS</replaceable>][,<replaceable>UUID</replaceable>]</option></term>
              <listitem>
                <para>
                  The algorithm specified in
                  <ulink url="https://tools.ietf.org/html/rfc7217">RFC 7217</ulink> will be used to
                  generate interface identifiers. This mode can optionally take an IPv6 address
                  separated with a colon (<literal>:</literal>). If an IPv6 address is specified,
                  then an interface identifier is generated only when a prefix received in an RA
                  message matches the supplied address.
                </para>
                <para>
                  This mode can also optionally take a non-null UUID in the format which
                  <function>sd_id128_from_string()</function> accepts, e.g.
                  <literal>86b123b969ba4b7eb8b3d8605123525a</literal> or
                  <literal>86b123b9-69ba-4b7e-b8b3-d8605123525a</literal>. If a UUID is specified, the
                  value is used as the secret key to generate interface identifiers. If not specified,
                  then an application specific ID generated with the system's machine-ID will be used
                  as the secret key. See
                  <citerefentry><refentrytitle>sd-id128</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                  <citerefentry><refentrytitle>sd_id128_from_string</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                  and
                  <citerefentry><refentrytitle>sd_id128_get_machine</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
                </para>
                <para>
                  Note that the <literal>prefixstable</literal> algorithm uses both the interface
                  name and MAC address as input to the hash to compute the interface identifier, so
                  if either of those are changed the resulting interface identifier (and address)
                  will be changed, even if the prefix received in the RA message has not been
                  changed.
                </para>
              </listitem>
            </varlistentry>
          </variablelist>

          <para>If no address generation mode is specified (which is the default), or a received
          prefix does not match any of the addresses provided in <literal>prefixstable</literal>
          mode, then the EUI-64 algorithm will be used for Ethernet or InfiniBand interfaces,
          otherwise <literal>prefixstable</literal> will be used to form an interface identifier for
          that prefix.</para>

          <para>This setting can be specified multiple times. If an empty string is assigned, then
          the all previous assignments are cleared.</para>

          <para>Examples:
          <programlisting>Token=eui64
Token=::1a:2b:3c:4d
Token=static:::1a:2b:3c:4d
Token=prefixstable
Token=prefixstable:2002:da8:1::</programlisting></para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseDNS=</varname></term>
        <listitem>
          <para>When true (the default), the DNS servers received in the Router Advertisement will be used.</para>

          <para>This corresponds to the <option>nameserver</option> option in <citerefentry
          project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseDomains=</varname></term>
        <listitem>
          <para>Takes a boolean, or the special value <literal>route</literal>. When true, the domain name
          received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link,
          similarly to the effect of the <option>Domains=</option> setting. If set to
          <literal>route</literal>, the domain name received via IPv6 RA will be used for routing DNS queries
          only, but not for searching, similarly to the effect of the <option>Domains=</option> setting when
          the argument is prefixed with <literal>~</literal>. Defaults to false.</para>

          <para>It is recommended to enable this option only on trusted networks, as setting this affects resolution
          of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain
          only as routing domain, rather than as search domain, in order to not have it affect local resolution of
          single-label names.</para>

          <para>When set to true, this setting corresponds to the <option>domain</option> option in <citerefentry
          project='man-pages'><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouteTable=<replaceable>num</replaceable></varname></term>
        <listitem>
          <para>The table identifier for the routes received in the Router Advertisement. Takes one of
          predefined names <literal>default</literal>, <literal>main</literal>, and <literal>local</literal>,
          and names defined in <varname>RouteTable=</varname> in
          <citerefentry><refentrytitle>networkd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
          or a number between 1…4294967295.</para>

          <para>When used in combination with <varname>VRF=</varname>, the VRF's routing table is
          used when this parameter is not specified.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouteMetric=</varname></term>
        <listitem>
          <para>Set the routing metric for the routes received in the Router Advertisement. Takes an unsigned
          integer in the range 0…4294967295, or three unsigned integer separated with <literal>:</literal>,
          in that case the first one is used when the router preference is high, the second is for medium
          preference, and the last is for low preference
          (<literal><replaceable>high</replaceable>:<replaceable>medium</replaceable>:<replaceable>low</replaceable></literal>).
          Defaults to <literal>512:1024:2048</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>QuickAck=</varname></term>
        <listitem>
          <para>Takes a boolean. When true, the TCP quick ACK mode is enabled for the routes configured by
          the received RAs. When unset, the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseMTU=</varname></term>
        <listitem>
          <para>Takes a boolean. When true, the MTU received in the Router Advertisement will be
          used. Defaults to true.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseGateway=</varname></term>
        <listitem>
          <para>When true (the default), the router address will be configured as the default gateway.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseRoutePrefix=</varname></term>
        <listitem>
          <para>When true (the default), the routes corresponding to the route prefixes received in
          the Router Advertisement will be configured.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseAutonomousPrefix=</varname></term>
        <listitem>
          <para>When true (the default), the autonomous prefix received in the Router Advertisement will be used and take
          precedence over any statically configured ones.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseOnLinkPrefix=</varname></term>
        <listitem>
          <para>When true (the default), the onlink prefix received in the Router Advertisement will be
          used and takes precedence over any statically configured ones.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouterDenyList=</varname></term>
        <listitem>
          <para>A whitespace-separated list of IPv6 router addresses. Each address can optionally
          take a prefix length after <literal>/</literal>. Any information advertised by the listed
          router is ignored.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouterAllowList=</varname></term>
        <listitem>
          <para>A whitespace-separated list of IPv6 router addresses. Each address can optionally
          take a prefix length after <literal>/</literal>. Only information advertised by the listed
          router is accepted. Note that if <varname>RouterAllowList=</varname> is configured then
          <varname>RouterDenyList=</varname> is ignored.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PrefixDenyList=</varname></term>
        <listitem>
          <para>A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its
          prefix length after <literal>/</literal>. IPv6 prefixes supplied via router advertisements
          in the list are ignored.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PrefixAllowList=</varname></term>
        <listitem>
          <para>A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its
          prefix length after <literal>/</literal>. IPv6 prefixes supplied via router advertisements
          in the list are allowed. Note that if <varname>PrefixAllowList=</varname> is configured
          then <varname>PrefixDenyList=</varname> is ignored.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouteDenyList=</varname></term>
        <listitem>
          <para>A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take
          its prefix length after <literal>/</literal>. IPv6 route prefixes supplied via router
          advertisements in the list are ignored.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouteAllowList=</varname></term>
        <listitem>
          <para>A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take
          its prefix length after <literal>/</literal>. IPv6 route prefixes supplied via router
          advertisements in the list are allowed. Note that if <varname>RouteAllowList=</varname> is
          configured then <varname>RouteDenyList=</varname> is ignored.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DHCPv6Client=</varname></term>
        <listitem>
          <para>Takes a boolean, or the special value <literal>always</literal>. When true, the
          DHCPv6 client will be started in <literal>solicit</literal> mode if the RA has the
          <literal>managed</literal> flag or <literal>information-request</literal> mode if the RA
          lacks the <literal>managed</literal> flag but has the
          <literal>other configuration</literal> flag. If set to <literal>always</literal>, the
          DHCPv6 client will be started in <literal>solicit</literal> mode when an RA is received,
          even if neither the <literal>managed</literal> nor the
          <literal>other configuration</literal> flag is set in the RA. This will be ignored when
          <varname>WithoutRA=</varname> in the [DHCPv6] section is enabled, or
          <varname>UplinkInterface=:self</varname> in the [DHCPPrefixDelegation] section is
          specified. Defaults to true.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>NetLabel=</varname></term>
        <listitem>
          <para>This applies the NetLabel for the addresses received with RA, like
          <varname>NetLabel=</varname> in [Address] section applies it to statically configured
          addresses. See <varname>NetLabel=</varname> in [Address] section for more details.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[DHCPServer] Section Options</title>
    <para>The [DHCPServer] section contains settings for the DHCP server, if enabled via the
    <varname>DHCPServer=</varname> option described above:</para>

    <variablelist class='network-directives'>

      <varlistentry>
        <term><varname>ServerAddress=</varname></term>
        <listitem><para>Specifies server address for the DHCP server. Takes an IPv4 address with prefix
        length, for example 192.168.0.1/24. This setting may be useful when the link on
        which the DHCP server is running has multiple static addresses. When unset, one of static addresses
        in the link will be automatically selected. Defaults to unset.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PoolOffset=</varname></term>
        <term><varname>PoolSize=</varname></term>

        <listitem><para>Configures the pool of addresses to hand out. The pool
        is a contiguous sequence of IP addresses in the subnet configured for
        the server address, which does not include the subnet nor the broadcast
        address. <varname>PoolOffset=</varname> takes the offset of the pool
        from the start of subnet, or zero to use the default value.
        <varname>PoolSize=</varname> takes the number of IP addresses in the
        pool or zero to use the default value. By default, the pool starts at
        the first address after the subnet address and takes up the rest of
        the subnet, excluding the broadcast address. If the pool includes
        the server address (the default), this is reserved and not handed
        out to clients.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DefaultLeaseTimeSec=</varname></term>
        <term><varname>MaxLeaseTimeSec=</varname></term>

        <listitem><para>Control the default and maximum DHCP lease
        time to pass to clients. These settings take time values in seconds or
        another common time unit, depending on the suffix. The default
        lease time is used for clients that did not ask for a specific
        lease time. If a client asks for a lease time longer than the
        maximum lease time, it is automatically shortened to the
        specified time. The default lease time defaults to 1h, the
        maximum lease time to 12h. Shorter lease times are beneficial
        if the configuration data in DHCP leases changes frequently
        and clients shall learn the new settings with shorter
        latencies. Longer lease times reduce the generated DHCP
        network traffic.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UplinkInterface=</varname></term>
        <listitem><para>Specifies the name or the index of the uplink interface, or one of the special
        values <literal>:none</literal> and <literal>:auto</literal>. When emitting DNS, NTP, or SIP
        servers is enabled but no servers are specified, the servers configured in the uplink interface
        will be emitted. When <literal>:auto</literal>, the link which has a default gateway with the
        highest priority will be automatically selected. When <literal>:none</literal>, no uplink
        interface will be selected. Defaults to <literal>:auto</literal>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>EmitDNS=</varname></term>
        <term><varname>DNS=</varname></term>

        <listitem><para><varname>EmitDNS=</varname> takes a boolean. Configures whether the DHCP leases
        handed out to clients shall contain DNS server information. Defaults to <literal>yes</literal>.
        The DNS servers to pass to clients may be configured with the <varname>DNS=</varname> option,
        which takes a list of IPv4 addresses, or special value <literal>_server_address</literal> which
        will be converted to the address used by the DHCP server.</para>

        <para>If the <varname>EmitDNS=</varname> option is enabled but no servers configured, the
        servers are automatically propagated from an "uplink" interface that has appropriate servers
        set. The "uplink" interface is determined by the default route of the system with the highest
        priority. Note that this information is acquired at the time the lease is handed out, and does
        not take uplink interfaces into account that acquire DNS server information at a later point.
        If no suitable uplink interface is found the DNS server data from
        <filename>/etc/resolv.conf</filename> is used. Also, note that the leases are not refreshed if
        the uplink network configuration changes. To ensure clients regularly acquire the most current
        uplink DNS server information, it is thus advisable to shorten the DHCP lease time via
        <varname>MaxLeaseTimeSec=</varname> described above.</para>

        <para>This setting can be specified multiple times. If an empty string is specified, then all
        DNS servers specified earlier are cleared.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>EmitNTP=</varname></term>
        <term><varname>NTP=</varname></term>
        <term><varname>EmitSIP=</varname></term>
        <term><varname>SIP=</varname></term>
        <term><varname>EmitPOP3=</varname></term>
        <term><varname>POP3=</varname></term>
        <term><varname>EmitSMTP=</varname></term>
        <term><varname>SMTP=</varname></term>
        <term><varname>EmitLPR=</varname></term>
        <term><varname>LPR=</varname></term>

        <listitem><para>Similar to the <varname>EmitDNS=</varname> and <varname>DNS=</varname> settings
        described above, these settings configure whether and what server information for the indicate
        protocol shall be emitted as part of the DHCP lease. The same syntax, propagation semantics and
        defaults apply as for <varname>EmitDNS=</varname> and <varname>DNS=</varname>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>EmitRouter=</varname></term>
        <term><varname>Router=</varname></term>

        <listitem><para>The <varname>EmitRouter=</varname> setting takes a boolean value, and configures
        whether the DHCP lease should contain the router option. The <varname>Router=</varname> setting
        takes an IPv4 address, and configures the router address to be emitted. When the
        <varname>Router=</varname> setting is not specified, then the server address will be used for
        the router option. When the <varname>EmitRouter=</varname> setting is disabled, the
        <varname>Router=</varname> setting will be ignored. The <varname>EmitRouter=</varname> setting
        defaults to true, and the <varname>Router=</varname> setting defaults to unset.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>EmitTimezone=</varname></term>
        <term><varname>Timezone=</varname></term>

        <listitem><para>Takes a boolean. Configures whether the DHCP leases handed out
        to clients shall contain timezone information. Defaults to <literal>yes</literal>. The
        <varname>Timezone=</varname> setting takes a timezone string
        (such as <literal>Europe/Berlin</literal> or
        <literal>UTC</literal>) to pass to clients. If no explicit
        timezone is set, the system timezone of the local host is
        propagated, as determined by the
        <filename>/etc/localtime</filename> symlink.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>BootServerAddress=</varname></term>

        <listitem>
          <para>Takes an IPv4 address of the boot server used by e.g. PXE boot systems. When specified, this
          address is sent in the <option>siaddr</option> field of the DHCP message header. See <ulink
          url="https://www.rfc-editor.org/rfc/rfc2131.html">RFC 2131</ulink> for more details. Defaults to
          unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>BootServerName=</varname></term>

        <listitem>
          <para>Takes a name of the boot server used by e.g. PXE boot systems. When specified, this name is
          sent in the DHCP option 66 ("TFTP server name"). See <ulink
          url="https://www.rfc-editor.org/rfc/rfc2132.html">RFC 2132</ulink> for more details. Defaults to
          unset.</para>

          <para>Note that typically setting one of <varname>BootServerName=</varname> or
          <varname>BootServerAddress=</varname> is sufficient, but both can be set too, if desired.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>BootFilename=</varname></term>

        <listitem>
          <para>Takes a path or URL to a file loaded by e.g. a PXE boot loader. When specified, this path is
          sent in the DHCP option 67 ("Bootfile name"). See <ulink
          url="https://www.rfc-editor.org/rfc/rfc2132.html">RFC 2132</ulink> for more details. Defaults to
          unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SendOption=</varname></term>
        <listitem>
          <para>Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type
          and data (<literal><replaceable>option</replaceable>:<replaceable>type</replaceable>:<replaceable>value</replaceable></literal>).
          The option number is an integer in the range 1…254. The type takes one of <literal>uint8</literal>,
          <literal>uint16</literal>, <literal>uint32</literal>, <literal>ipv4address</literal>, <literal>ipv6address</literal>, or
          <literal>string</literal>. Special characters in the data string may be escaped using
          <ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
          escapes</ulink>. This setting can be specified multiple times. If an empty string is specified,
          then all options specified earlier are cleared. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SendVendorOption=</varname></term>
        <listitem>
          <para>Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type
          and data (<literal><replaceable>option</replaceable>:<replaceable>type</replaceable>:<replaceable>value</replaceable></literal>).
          The option number is an integer in the range 1…254. The type takes one of <literal>uint8</literal>,
          <literal>uint16</literal>, <literal>uint32</literal>, <literal>ipv4address</literal>, or
          <literal>string</literal>. Special characters in the data string may be escaped using
          <ulink url="https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences">C-style
          escapes</ulink>. This setting can be specified multiple times. If an empty string is specified,
          then all options specified earlier are cleared. Defaults to unset.</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><varname>BindToInterface=</varname></term>
        <listitem>
          <para>Takes a boolean value. When <literal>yes</literal>, DHCP server socket will be bound
          to its network interface and all socket communication will be restricted to this interface.
          Defaults to <literal>yes</literal>, except if <varname>RelayTarget=</varname> is used (see below),
          in which case it defaults to <literal>no</literal>.</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><varname>RelayTarget=</varname></term>
        <listitem>
          <para>Takes an IPv4 address, which must be in the format described in
          <citerefentry project='man-pages'><refentrytitle>inet_pton</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
          Turns this DHCP server into a DHCP relay agent. See <ulink url="https://tools.ietf.org/html/rfc1542">RFC 1542</ulink>.
          The address is the address of DHCP server or another relay agent to forward DHCP messages to and from.</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><varname>RelayAgentCircuitId=</varname></term>
        <listitem>
          <para>Specifies value for Agent Circuit ID suboption of Relay Agent Information option.
          Takes a string, which must be in the format <literal>string:<replaceable>value</replaceable></literal>,
          where <literal><replaceable>value</replaceable></literal> should be replaced with the value of the suboption.
          Defaults to unset (means no Agent Circuit ID suboption is generated).
          Ignored if <varname>RelayTarget=</varname> is not specified.</para>
        </listitem>
      </varlistentry>
      <varlistentry>
        <term><varname>RelayAgentRemoteId=</varname></term>
        <listitem>
          <para>Specifies value for Agent Remote ID suboption of Relay Agent Information option.
          Takes a string, which must be in the format <literal>string:<replaceable>value</replaceable></literal>,
          where <literal><replaceable>value</replaceable></literal> should be replaced with the value of the suboption.
          Defaults to unset (means no Agent Remote ID suboption is generated).
          Ignored if <varname>RelayTarget=</varname> is not specified.</para>
        </listitem>
      </varlistentry>

    </variablelist>
  </refsect1>

  <refsect1>
    <title>[DHCPServerStaticLease] Section Options</title>
    <para>The <literal>[DHCPServerStaticLease]</literal> section configures a static DHCP lease to assign a
    fixed IPv4 address to a specific device based on its MAC address. This section can be specified multiple
    times.</para>

    <variablelist class='network-directives'>
      <varlistentry>
        <term><varname>MACAddress=</varname></term>

        <listitem><para>The hardware address of a device to match. This key is mandatory.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Address=</varname></term>

        <listitem><para>The IPv4 address that should be assigned to the device that was matched with
        <varname>MACAddress=</varname>. This key is mandatory.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[IPv6SendRA] Section Options</title>
    <para>The [IPv6SendRA] section contains settings for sending IPv6 Router Advertisements and whether
    to act as a router, if enabled via the <varname>IPv6SendRA=</varname> option described above. IPv6
    network prefixes or routes are defined with one or more [IPv6Prefix] or [IPv6RoutePrefix] sections.
    </para>

    <variablelist class='network-directives'>

      <varlistentry>
        <term><varname>Managed=</varname></term>
        <term><varname>OtherInformation=</varname></term>

        <listitem><para>Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6
        addresses on the network link when <varname>Managed=</varname>
        is set to <literal>true</literal> or if only additional network
        information can be obtained via DHCPv6 for the network link when
        <varname>OtherInformation=</varname> is set to
        <literal>true</literal>. Both settings default to
        <literal>false</literal>, which means that a DHCPv6 server is not being
        used.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouterLifetimeSec=</varname></term>

        <listitem><para>Takes a timespan. Configures the IPv6 router lifetime in seconds. The value must be 0
        seconds, or between 4 seconds and 9000 seconds. When set to 0, the host is not acting as a router.
        Defaults to 1800 seconds (30 minutes).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouterPreference=</varname></term>

        <listitem><para>Configures IPv6 router preference if
        <varname>RouterLifetimeSec=</varname> is non-zero. Valid values are
        <literal>high</literal>, <literal>medium</literal> and
        <literal>low</literal>, with <literal>normal</literal> and
        <literal>default</literal> added as synonyms for
        <literal>medium</literal> just to make configuration easier. See
        <ulink url="https://tools.ietf.org/html/rfc4191">RFC 4191</ulink>
        for details. Defaults to <literal>medium</literal>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UplinkInterface=</varname></term>
        <listitem><para>Specifies the name or the index of the uplink interface, or one of the special
        values <literal>:none</literal> and <literal>:auto</literal>. When emitting DNS servers or
        search domains is enabled but no servers are specified, the servers configured in the uplink
        interface will be emitted. When <literal>:auto</literal>, the value specified to the same
        setting in the [DHCPPrefixDelegation] section will be used if
        <varname>DHCPPrefixDelegation=</varname> is enabled, otherwise the link which has a default
        gateway with the highest priority will be automatically selected. When <literal>:none</literal>,
        no uplink interface will be selected. Defaults to <literal>:auto</literal>.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>EmitDNS=</varname></term>
        <term><varname>DNS=</varname></term>

        <listitem><para><varname>DNS=</varname> specifies a list of recursive DNS server IPv6 addresses
        that are distributed via Router Advertisement messages when <varname>EmitDNS=</varname> is true.
        <varname>DNS=</varname> also takes special value <literal>_link_local</literal>; in that case
        the IPv6 link-local address is distributed. If <varname>DNS=</varname> is empty, DNS servers are
        read from the [Network] section. If the [Network] section does not contain any DNS servers
        either, DNS servers from the uplink interface specified in <varname>UplinkInterface=</varname>
        will be used. When <varname>EmitDNS=</varname> is false, no DNS server information is sent in
        Router Advertisement messages. <varname>EmitDNS=</varname> defaults to true.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>EmitDomains=</varname></term>
        <term><varname>Domains=</varname></term>

        <listitem><para>A list of DNS search domains distributed via Router Advertisement messages when
        <varname>EmitDomains=</varname> is true. If <varname>Domains=</varname> is empty, DNS search
        domains are read from the [Network] section. If the [Network] section does not contain any DNS
        search domains either, DNS search domains from the uplink interface specified in
        <varname>UplinkInterface=</varname> will be used. When <varname>EmitDomains=</varname> is false,
        no DNS search domain information is sent in Router Advertisement messages.
        <varname>EmitDomains=</varname> defaults to true.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DNSLifetimeSec=</varname></term>

        <listitem><para>Lifetime in seconds for the DNS server addresses listed in
        <varname>DNS=</varname> and search domains listed in <varname>Domains=</varname>. Defaults to
        3600 seconds (one hour).</para></listitem>
      </varlistentry>

    </variablelist>
    </refsect1>

    <refsect1>
    <title>[IPv6Prefix] Section Options</title>
    <para>One or more [IPv6Prefix] sections contain the IPv6 prefixes that are announced via Router
    Advertisements. See <ulink url="https://tools.ietf.org/html/rfc4861">RFC 4861</ulink> for further
    details.</para>

    <variablelist class='network-directives'>

      <varlistentry>
        <term><varname>AddressAutoconfiguration=</varname></term>
        <term><varname>OnLink=</varname></term>

        <listitem><para>Takes a boolean to specify whether IPv6 addresses can be
        autoconfigured with this prefix and whether the prefix can be used for
        onlink determination. Both settings default to <literal>true</literal>
        in order to ease configuration.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Prefix=</varname></term>

        <listitem><para>The IPv6 prefix that is to be distributed to hosts. Similarly to configuring static
        IPv6 addresses, the setting is configured as an IPv6 prefix and its prefix length, separated by a
        <literal>/</literal> character. Use multiple [IPv6Prefix] sections to configure multiple IPv6
        prefixes since prefix lifetimes, address autoconfiguration and onlink status may differ from one
        prefix to another.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PreferredLifetimeSec=</varname></term>
        <term><varname>ValidLifetimeSec=</varname></term>

        <listitem><para>Preferred and valid lifetimes for the prefix measured in seconds.
        <varname>PreferredLifetimeSec=</varname> defaults to 1800 seconds (30 minutes) and
        <varname>ValidLifetimeSec=</varname> defaults to 3600 seconds (one hour).</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Assign=</varname></term>
        <listitem><para>Takes a boolean. When true, adds an address from the prefix. Default to false.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Token=</varname></term>
        <listitem>
          <para>Specifies an optional address generation mode for assigning an address in each
          prefix. This accepts the same syntax as <varname>Token=</varname> in the [IPv6AcceptRA]
          section. If <varname>Assign=</varname> is set to false, then this setting will be ignored.
          Defaults to unset, which means the EUI-64 algorithm will be used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RouteMetric=</varname></term>
        <listitem>
          <para>The metric of the prefix route. Takes an unsigned integer in the range 0…4294967295.
          When unset or set to 0, the kernel's default value is used. This setting is ignored when
          <varname>Assign=</varname> is false.</para>
        </listitem>
      </varlistentry>
    </variablelist>
    </refsect1>

    <refsect1>
    <title>[IPv6RoutePrefix] Section Options</title>
    <para>One or more [IPv6RoutePrefix] sections contain the IPv6
    prefix routes that are announced via Router Advertisements. See
    <ulink url="https://tools.ietf.org/html/rfc4191">RFC 4191</ulink>
    for further details.</para>

    <variablelist class='network-directives'>

      <varlistentry>
        <term><varname>Route=</varname></term>

        <listitem><para>The IPv6 route that is to be distributed to hosts. Similarly to configuring static
        IPv6 routes, the setting is configured as an IPv6 prefix routes and its prefix route length,
        separated by a <literal>/</literal> character. Use multiple [IPv6RoutePrefix] sections to configure
        multiple IPv6 prefix routes.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>LifetimeSec=</varname></term>

        <listitem><para>Lifetime for the route prefix measured in seconds.
        <varname>LifetimeSec=</varname> defaults to 3600 seconds (one hour).</para></listitem>
      </varlistentry>

    </variablelist>
    </refsect1>

    <refsect1>
    <title>[Bridge] Section Options</title>
      <para>The [Bridge] section accepts the following keys:</para>
      <variablelist class='network-directives'>
        <varlistentry>
          <term><varname>UnicastFlood=</varname></term>
          <listitem>
            <para>Takes a boolean. Controls whether the bridge should flood
            traffic for which an FDB entry is missing and the destination
            is unknown through this port. When unset, the kernel's default will be used.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>MulticastFlood=</varname></term>
          <listitem>
            <para>Takes a boolean. Controls whether the bridge should flood
            traffic for which an MDB entry is missing and the destination
            is unknown through this port. When unset, the kernel's default will be used.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>MulticastToUnicast=</varname></term>
          <listitem>
            <para>Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of
            the bridge. Which means unicast copies are only delivered to hosts which are interested in it.
            When unset, the kernel's default will be used.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>NeighborSuppression=</varname></term>
          <listitem>
            <para>Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for
            this port. When unset, the kernel's default will be used.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>Learning=</varname></term>
          <listitem>
            <para>Takes a boolean. Configures whether MAC address learning is enabled for
            this port. When unset, the kernel's default will be used.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>HairPin=</varname></term>
          <listitem>
            <para>Takes a boolean. Configures whether traffic may be sent back out of the port on which it
            was received. When this flag is false, then the bridge will not forward traffic back out of the
            receiving port. When unset, the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>Isolated=</varname></term>
          <listitem>
            <para>Takes a boolean. Configures whether this port is isolated or not. Within a bridge,
            isolated ports can only communicate with non-isolated ports. When set to true, this port can only
            communicate with other ports whose Isolated setting is false.  When set to false, this port
            can communicate with any other ports. When unset, the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>UseBPDU=</varname></term>
          <listitem>
            <para>Takes a boolean. Configures whether STP Bridge Protocol Data Units will be
            processed by the bridge port. When unset, the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>FastLeave=</varname></term>
          <listitem>
            <para>Takes a boolean. This flag allows the bridge to immediately stop multicast
            traffic on a port that receives an IGMP Leave message. It is only used with
            IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>AllowPortToBeRoot=</varname></term>
          <listitem>
            <para>Takes a boolean. Configures whether a given port is allowed to
            become a root port. Only used when STP is enabled on the bridge.
            When unset, the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>ProxyARP=</varname></term>
          <listitem>
            <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port.
            When unset, the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>ProxyARPWiFi=</varname></term>
          <listitem>
            <para>Takes a boolean. Configures whether proxy ARP to be enabled on this port
            which meets extended requirements by IEEE 802.11 and Hotspot 2.0 specifications.
            When unset, the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>MulticastRouter=</varname></term>
          <listitem>
            <para>Configures this port for having multicast routers attached. A port with a multicast
            router will receive all multicast traffic. Takes one of <literal>no</literal>
            to disable multicast routers on this port, <literal>query</literal> to let the system detect
            the presence of routers, <literal>permanent</literal> to permanently enable multicast traffic
            forwarding on this port, or <literal>temporary</literal> to enable multicast routers temporarily
            on this port, not depending on incoming queries. When unset, the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>Cost=</varname></term>
          <listitem>
            <para>Sets the "cost" of sending packets of this interface.
            Each port in a bridge may have a different speed and the cost
            is used to decide which link to use. Faster interfaces
            should have lower costs. It is an integer value between 1 and
            65535.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>Priority=</varname></term>
          <listitem>
            <para>Sets the "priority" of sending packets on this interface.
            Each port in a bridge may have a different priority which is used
            to decide which link to use. Lower value means higher priority.
            It is an integer value between 0 to 63. Networkd does not set any
            default, meaning the kernel default value of 32 is used.</para>
          </listitem>
        </varlistentry>
      </variablelist>
  </refsect1>
  <refsect1>
    <title>[BridgeFDB] Section Options</title>
      <para>The [BridgeFDB] section manages the forwarding database table of a port and accepts the following
      keys. Specify several [BridgeFDB] sections to configure several static MAC table entries.</para>

      <variablelist class='network-directives'>
        <varlistentry>
          <term><varname>MACAddress=</varname></term>
          <listitem>
            <para>As in the [Network] section. This key is mandatory.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>Destination=</varname></term>
          <listitem>
            <para>Takes an IP address of the destination VXLAN tunnel endpoint.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>VLANId=</varname></term>
          <listitem>
            <para>The VLAN ID for the new static MAC table entry. If
            omitted, no VLAN ID information is appended to the new static MAC
            table entry.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>VNI=</varname></term>
          <listitem>
            <para>The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to
            the remote VXLAN tunnel endpoint. Takes a number in the range 1…16777215.
            Defaults to unset.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>AssociatedWith=</varname></term>
          <listitem>
            <para>Specifies where the address is associated with. Takes one of <literal>use</literal>,
            <literal>self</literal>, <literal>master</literal> or <literal>router</literal>.
            <literal>use</literal> means the address is in use. User space can use this option to
            indicate to the kernel that the fdb entry is in use. <literal>self</literal> means
            the address is associated with the port drivers fdb. Usually hardware. <literal>master</literal>
            means the address is associated with master devices fdb. <literal>router</literal> means
            the destination address is associated with a router. Note that it's valid if the referenced
            device is a VXLAN type device and has route shortcircuit enabled. Defaults to <literal>self</literal>.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>OutgoingInterface=</varname></term>
          <listitem>
            <para>Specifies the name or index of the outgoing interface for the VXLAN device driver to
            reach the remote VXLAN tunnel endpoint. Defaults to unset.</para>
          </listitem>
        </varlistentry>
      </variablelist>
  </refsect1>
  <refsect1>
    <title>[BridgeMDB] Section Options</title>
      <para>The [BridgeMDB] section manages the multicast membership entries forwarding database table of a port and accepts the following
      keys. Specify several [BridgeMDB] sections to configure several permanent multicast membership entries.</para>

      <variablelist class='network-directives'>
        <varlistentry>
          <term><varname>MulticastGroupAddress=</varname></term>
          <listitem>
            <para>Specifies the IPv4 or IPv6 multicast group address to add. This setting is mandatory.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>VLANId=</varname></term>
          <listitem>
            <para>The VLAN ID for the new entry. Valid ranges are 0 (no VLAN) to 4094. Optional, defaults to 0.</para>
          </listitem>
        </varlistentry>
      </variablelist>
  </refsect1>

  <refsect1>
    <title>[LLDP] Section Options</title>
      <para>The [LLDP] section manages the Link Layer Discovery Protocol (LLDP) and accepts the following
      keys:</para>
      <variablelist class='network-directives'>
        <varlistentry>
          <term><varname>MUDURL=</varname></term>
          <listitem>
            <para>When configured, the specified Manufacturer Usage Descriptions (MUD) URL will be sent in
            LLDP packets. The syntax and semantics are the same as for <varname>MUDURL=</varname> in the
            [DHCPv4] section described above.</para>

            <para>The MUD URLs received via LLDP packets are saved and can be read using the
            <function>sd_lldp_neighbor_get_mud_url()</function> function.</para>
          </listitem>
        </varlistentry>
      </variablelist>
  </refsect1>

  <refsect1>
    <title>[CAN] Section Options</title>
      <para>The [CAN] section manages the Controller Area Network (CAN bus) and accepts the
      following keys:</para>
      <variablelist class='network-directives'>
        <varlistentry>
          <term><varname>BitRate=</varname></term>
          <listitem>
            <para>The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of 1000 can
            be used here. Takes a number in the range 1…4294967295.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>SamplePoint=</varname></term>
          <listitem>
            <para>Optional sample point in percent with one decimal (e.g. <literal>75%</literal>,
            <literal>87.5%</literal>) or permille (e.g. <literal>875‰</literal>). This will be ignored when
            <varname>BitRate=</varname> is unspecified.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>TimeQuantaNSec=</varname></term>
          <term><varname>PropagationSegment=</varname></term>
          <term><varname>PhaseBufferSegment1=</varname></term>
          <term><varname>PhaseBufferSegment2=</varname></term>
          <term><varname>SyncJumpWidth=</varname></term>
          <listitem>
            <para>Specifies the time quanta, propagation segment, phase buffer segment 1 and 2, and the
            synchronization jump width, which allow one to define the CAN bit-timing in a hardware
            independent format as proposed by the Bosch CAN 2.0 Specification.
            <varname>TimeQuantaNSec=</varname> takes a timespan in nanoseconds.
            <varname>PropagationSegment=</varname>, <varname>PhaseBufferSegment1=</varname>,
            <varname>PhaseBufferSegment2=</varname>, and <varname>SyncJumpWidth=</varname> take number
            of time quantum specified in <varname>TimeQuantaNSec=</varname> and must be an unsigned
            integer in the range 0…4294967295. These settings except for
            <varname>SyncJumpWidth=</varname> will be ignored when <varname>BitRate=</varname> is
            specified.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>DataBitRate=</varname></term>
          <term><varname>DataSamplePoint=</varname></term>
          <listitem>
            <para>The bitrate and sample point for the data phase, if CAN-FD is used. These settings are
            analogous to the <varname>BitRate=</varname> and <varname>SamplePoint=</varname> keys.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>DataTimeQuantaNSec=</varname></term>
          <term><varname>DataPropagationSegment=</varname></term>
          <term><varname>DataPhaseBufferSegment1=</varname></term>
          <term><varname>DataPhaseBufferSegment2=</varname></term>
          <term><varname>DataSyncJumpWidth=</varname></term>
          <listitem>
            <para>Specifies the time quanta, propagation segment, phase buffer segment 1 and 2, and the
            synchronization jump width for the data phase, if CAN-FD is used. These settings are
            analogous to the <varname>TimeQuantaNSec=</varname> or related settings.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>FDMode=</varname></term>
          <listitem>
            <para>Takes a boolean. When <literal>yes</literal>, CAN-FD mode is enabled for the interface.
            Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using
            the <varname>DataBitRate=</varname> and <varname>DataSamplePoint=</varname> keys, or
            <varname>DataTimeQuanta=</varname> and related settings.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>FDNonISO=</varname></term>
          <listitem>
            <para>Takes a boolean. When <literal>yes</literal>, non-ISO CAN-FD mode is enabled for the
            interface. When unset, the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>RestartSec=</varname></term>
          <listitem>
            <para>Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be
            triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can
            be specified using decimals (e.g. <literal>0.1s</literal>) or a <literal>ms</literal> or
            <literal>us</literal> postfix. Using <literal>infinity</literal> or <literal>0</literal> will turn the
            automatic restart off. By default automatic restart is disabled.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>Termination=</varname></term>
          <listitem>
            <para>Takes a boolean or a termination resistor value in ohm in the range 0…65535. When
            <literal>yes</literal>, the termination resistor is set to 120 ohm. When
            <literal>no</literal> or <literal>0</literal> is set, the termination resistor is disabled.
            When unset, the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>TripleSampling=</varname></term>
          <listitem>
            <para>Takes a boolean. When <literal>yes</literal>, three samples (instead of one) are used to determine
            the value of a received bit by majority rule. When unset, the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>BusErrorReporting=</varname></term>
          <listitem>
            <para>Takes a boolean. When <literal>yes</literal>, reporting of CAN bus errors is activated
            (those include single bit, frame format, and bit stuffing errors, unable to send dominant bit,
            unable to send recessive bit, bus overload, active error announcement, error occurred on
            transmission). When unset, the kernel's default will be used. Note: in case of a CAN bus with a
            single CAN device, sending a CAN frame may result in a huge number of CAN bus errors.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>ListenOnly=</varname></term>
          <listitem>
            <para>Takes a boolean. When <literal>yes</literal>, listen-only mode is enabled. When the
            interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK
            bit. Listen-only mode is important to debug CAN networks without interfering with the
            communication or acknowledge the CAN frame. When unset, the kernel's default will be used.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>Loopback=</varname></term>
          <listitem>
            <para>Takes a boolean. When <literal>yes</literal>, loopback mode is enabled. When the
            loopback mode is enabled, the interface treats messages transmitted by itself as received
            messages. The loopback mode is important to debug CAN networks. When unset, the kernel's
            default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>OneShot=</varname></term>
          <listitem>
            <para>Takes a boolean. When <literal>yes</literal>, one-shot mode is enabled. When unset,
            the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>PresumeAck=</varname></term>
          <listitem>
            <para>Takes a boolean. When <literal>yes</literal>, the interface will ignore missing CAN
            ACKs. When unset, the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>ClassicDataLengthCode=</varname></term>
          <listitem>
            <para>Takes a boolean. When <literal>yes</literal>, the interface will handle the 4bit data
            length code (DLC). When unset, the kernel's default will be used.</para>
          </listitem>
        </varlistentry>
      </variablelist>
  </refsect1>

  <refsect1>
    <title>[IPoIB] Section Options</title>
      <para>The [IPoIB] section manages the IP over Infiniband and accepts the following keys:</para>
      <variablelist class='network-directives'>
        <xi:include href="systemd.netdev.xml" xpointer="ipoib_mode" />
        <xi:include href="systemd.netdev.xml" xpointer="ipoib_umcast" />
      </variablelist>
  </refsect1>

  <refsect1>
    <title>[QDisc] Section Options</title>
    <para>The [QDisc] section manages the traffic control queueing discipline (qdisc).</para>

    <variablelist class='network-directives'>
      <varlistentry>
        <term><varname>Parent=</varname></term>
        <listitem>
          <para>Specifies the parent Queueing Discipline (qdisc). Takes one of <literal>clsact</literal>
          or <literal>ingress</literal>. This is mandatory.</para>
        </listitem>
      </varlistentry>

      <xi:include href="tc.xml" xpointer="qdisc-handle" />
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[NetworkEmulator] Section Options</title>
    <para>The [NetworkEmulator] section manages the queueing discipline (qdisc) of the network emulator. It
    can be used to configure the kernel packet scheduler and simulate packet delay and loss for UDP or TCP
    applications, or limit the bandwidth usage of a particular service to simulate internet connections.
    </para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>DelaySec=</varname></term>
        <listitem>
          <para>Specifies the fixed amount of delay to be added to all packets going out of the
          interface. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DelayJitterSec=</varname></term>
        <listitem>
          <para>Specifies the chosen delay to be added to the packets outgoing to the network
          interface. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PacketLimit=</varname></term>
        <listitem>
          <para>Specifies the maximum number of packets the qdisc may hold queued at a time.
          An unsigned integer in the range 0…4294967294. Defaults to 1000.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>LossRate=</varname></term>
        <listitem>
          <para>Specifies an independent loss probability to be added to the packets outgoing from the
          network interface. Takes a percentage value, suffixed with "%". Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DuplicateRate=</varname></term>
        <listitem>
          <para>Specifies that the chosen percent of packets is duplicated before queuing them.
          Takes a percentage value, suffixed with "%". Defaults to unset.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[TokenBucketFilter] Section Options</title>
    <para>The [TokenBucketFilter] section manages the queueing discipline (qdisc) of token bucket filter
    (tbf).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>LatencySec=</varname></term>
        <listitem>
          <para>Specifies the latency parameter, which specifies the maximum amount of time a
          packet can sit in the Token Bucket Filter (TBF). Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>LimitBytes=</varname></term>
        <listitem>
          <para>Takes the number of bytes that can be queued waiting for tokens to become available.
          When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes,
          respectively, to the base of 1024. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>BurstBytes=</varname></term>
        <listitem>
          <para>Specifies the size of the bucket. This is the maximum amount of bytes that tokens
          can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is
          parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to
          unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Rate=</varname></term>
        <listitem>
          <para>Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified
          bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of 1000.
          Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MPUBytes=</varname></term>
        <listitem>
          <para>The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes)
          for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
          Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to zero.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PeakRate=</varname></term>
        <listitem>
          <para>Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the
          specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
          1000. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MTUBytes=</varname></term>
        <listitem>
          <para>Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified
          size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024.
          Defaults to unset.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[PIE] Section Options</title>
    <para>The [PIE] section manages the queueing discipline (qdisc) of Proportional Integral
    controller-Enhanced (PIE).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>PacketLimit=</varname></term>
        <listitem>
          <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
          incoming packets are dropped. An unsigned integer in the range 1…4294967294. Defaults to unset and
          kernel's default is used.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[FlowQueuePIE] Section Options</title>
    <para>The <literal>[FlowQueuePIE]</literal> section manages the queueing discipline
    (qdisc) of Flow Queue Proportional Integral controller-Enhanced (fq_pie).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>PacketLimit=</varname></term>
        <listitem>
          <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
          incoming packets are dropped. An unsigned integer ranges 1 to 4294967294. Defaults to unset and
          kernel's default is used.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[StochasticFairBlue] Section Options</title>
    <para>The [StochasticFairBlue] section manages the queueing discipline (qdisc) of stochastic fair blue
    (sfb).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>PacketLimit=</varname></term>
        <listitem>
          <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
          incoming packets are dropped. An unsigned integer in the range 0…4294967294. Defaults to unset and
          kernel's default is used.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[StochasticFairnessQueueing] Section Options</title>
    <para>The [StochasticFairnessQueueing] section manages the queueing discipline (qdisc) of stochastic
    fairness queueing (sfq).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>PerturbPeriodSec=</varname></term>
        <listitem>
          <para>Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[BFIFO] Section Options</title>
    <para>The [BFIFO] section manages the queueing discipline (qdisc) of Byte limited Packet First In First
    Out (bfifo).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>LimitBytes=</varname></term>
        <listitem>
          <para>Specifies the hard limit in bytes on the FIFO buffer size. The size limit prevents overflow
          in case the kernel is unable to dequeue packets as quickly as it receives them. When this limit is
          reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed
          as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to unset and
          kernel default is used.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[PFIFO] Section Options</title>
    <para>The [PFIFO] section manages the queueing discipline (qdisc) of Packet First In First Out
    (pfifo).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>PacketLimit=</varname></term>
        <listitem>
          <para>Specifies the hard limit on the number of packets in the FIFO queue. The size limit prevents
          overflow in case the kernel is unable to dequeue packets as quickly as it receives them. When this
          limit is reached, incoming packets are dropped. An unsigned integer in the range
          0…4294967294. Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[PFIFOHeadDrop] Section Options</title>
    <para>The [PFIFOHeadDrop] section manages the queueing discipline (qdisc) of Packet First In First Out
    Head Drop (pfifo_head_drop).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>PacketLimit=</varname></term>
        <listitem>
          <para>As in [PFIFO] section.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
     <title>[PFIFOFast] Section Options</title>
     <para>The [PFIFOFast] section manages the queueing discipline (qdisc) of Packet First In First Out Fast
     (pfifo_fast).</para>

     <variablelist class='network-directives'>
       <xi:include href="tc.xml" xpointer="qdisc-parent" />
       <xi:include href="tc.xml" xpointer="qdisc-handle" />
     </variablelist>
  </refsect1>

  <refsect1>
    <title>[CAKE] Section Options</title>
    <para>The [CAKE] section manages the queueing discipline (qdisc) of Common Applications Kept Enhanced
    (CAKE).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>Bandwidth=</varname></term>
        <listitem>
          <para>Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is
          parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of 1000. Defaults to
          unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>AutoRateIngress=</varname></term>
        <listitem>
          <para>Takes a boolean value. Enables automatic capacity estimation based on traffic arriving
          at this qdisc. This is most likely to be useful with cellular links, which tend to change
          quality randomly. If this setting is enabled, the <varname>Bandwidth=</varname> setting is
          used as an initial estimate. Defaults to unset, and the kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>OverheadBytes=</varname></term>
        <listitem>
          <para>Specifies that bytes to be addeded to the size of each packet. Bytes may be negative.
          Takes an integer in the range -64…256. Defaults to unset and kernel's default is used.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MPUBytes=</varname></term>
        <listitem>
          <para>Rounds each packet (including overhead) up to the specified bytes. Takes an integer in
          the range 1…256. Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>CompensationMode=</varname></term>
        <listitem>
          <para>Takes one of <literal>none</literal>, <literal>atm</literal>, or <literal>ptm</literal>.
          Specifies the compensation mode for overhead calculation. When <literal>none</literal>, no
          compensation is taken into account. When <literal>atm</literal>, enables the compensation for
          ATM cell framing, which is normally found on ADSL links. When <literal>ptm</literal>, enables
          the compensation for PTM encoding, which is normally found on VDSL2 links and uses a 64b/65b
          encoding scheme. Defaults to unset and the kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>UseRawPacketSize=</varname></term>
        <listitem>
          <para>Takes a boolean value. When true, the packet size reported by the Linux kernel will be
          used, instead of the underlying IP packet size. Defaults to unset, and the kernel's default
          is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>FlowIsolationMode=</varname></term>
        <listitem>
          <para>CAKE places packets from different flows into different queues, then packets from each
          queue are delivered fairly. This specifies whether the fairness is based on source address,
          destination address, individual flows, or any combination of those. The available values are:
          </para>

          <variablelist>
            <varlistentry>
              <term><option>none</option></term>
              <listitem><para>
                The flow isolation is disabled, and all traffic passes through a single queue.
              </para></listitem>
            </varlistentry>
            <varlistentry>
              <term><option>src-host</option></term>
              <listitem><para>
                Flows are defined only by source address. Equivalent to the <literal>srchost</literal>
                option for <command>tc qdisc</command> command. See also
                <citerefentry project='man-pages'><refentrytitle>tc-cake</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
              </para></listitem>
            </varlistentry>
            <varlistentry>
              <term><option>dst-host</option></term>
              <listitem><para>
                Flows are defined only by destination address. Equivalent to the
                <literal>dsthost</literal> option for <command>tc qdisc</command> command. See also
                <citerefentry project='man-pages'><refentrytitle>tc-cake</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
              </para></listitem>
            </varlistentry>
            <varlistentry>
              <term><option>hosts</option></term>
              <listitem><para>
                Flows are defined by source-destination host pairs. Equivalent to the same option for
                <command>tc qdisc</command> command. See also
                <citerefentry project='man-pages'><refentrytitle>tc-cake</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
              </para></listitem>
            </varlistentry>
            <varlistentry>
              <term><option>flows</option></term>
              <listitem><para>
                Flows are defined by the entire 5-tuple of source address, destination address,
                transport protocol, source port and destination port. Equivalent to the same option for
                <command>tc qdisc</command> command. See also
                <citerefentry project='man-pages'><refentrytitle>tc-cake</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
              </para></listitem>
            </varlistentry>
            <varlistentry>
              <term><option>dual-src-host</option></term>
              <listitem><para>
                Flows are defined by the 5-tuple (see <literal>flows</literal> in the above), and
                fairness is applied first over source addresses, then over individual flows. Equivalent
                to the <literal>dual-srchost</literal> option for <command>tc qdisc</command> command.
                See also
                <citerefentry project='man-pages'><refentrytitle>tc-cake</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
              </para></listitem>
            </varlistentry>
            <varlistentry>
              <term><option>dual-dst-host</option></term>
              <listitem><para>
                Flows are defined by the 5-tuple (see <literal>flows</literal> in the above), and
                fairness is applied first over destination addresses, then over individual flows.
                Equivalent to the <literal>dual-dsthost</literal> option for
                <command>tc qdisc</command> command. See also
                <citerefentry project='man-pages'><refentrytitle>tc-cake</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
              </para></listitem>
            </varlistentry>
            <varlistentry>
              <term><option>triple</option></term>
              <listitem><para>
                Flows are defined by the 5-tuple (see <literal>flows</literal>), and fairness is
                applied over source and destination addresses, and also over individual flows.
                Equivalent to the <literal>triple-isolate</literal> option for
                <command>tc qdisc</command> command. See also
                <citerefentry project='man-pages'><refentrytitle>tc-cake</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
              </para></listitem>
            </varlistentry>
          </variablelist>

          <para>Defaults to unset and the kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>NAT=</varname></term>
        <listitem>
          <para>Takes a boolean value. When true, CAKE performs a NAT lookup before applying
          flow-isolation rules, to determine the true addresses and port numbers of the packet, to
          improve fairness between hosts inside the NAT. This has no practical effect when
          <varname>FlowIsolationMode=</varname> is <literal>none</literal> or <literal>flows</literal>,
          or if NAT is performed on a different host. Defaults to unset, and the kernel's default is
          used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PriorityQueueingPreset=</varname></term>
        <listitem>
          <para>CAKE divides traffic into <literal>tins</literal>, and each tin has its own independent
          set of flow-isolation queues, bandwidth threshold, and priority. This specifies the preset of
          tin profiles. The available values are:</para>

          <variablelist>
            <varlistentry>
              <term><option>besteffort</option></term>
              <listitem><para>
                Disables priority queueing by placing all traffic in one tin.
              </para></listitem>
            </varlistentry>
            <varlistentry>
              <term><option>precedence</option></term>
              <listitem><para>
                Enables priority queueing based on the legacy interpretation of TOS
                <literal>Precedence</literal> field. Use of this preset on the modern Internet is
                firmly discouraged.
              </para></listitem>
            </varlistentry>
            <varlistentry>
              <term><option>diffserv8</option></term>
              <listitem><para>
                Enables priority queueing based on the Differentiated Service
                (<literal>DiffServ</literal>) field with eight tins: Background Traffic, High
                Throughput, Best Effort, Video Streaming, Low Latency Transactions, Interactive Shell,
                Minimum Latency, and Network Control.
              </para></listitem>
            </varlistentry>
            <varlistentry>
              <term><option>diffserv4</option></term>
              <listitem><para>
                Enables priority queueing based on the Differentiated Service
                (<literal>DiffServ</literal>) field with four tins: Background Traffic, Best Effort,
                Streaming Media, and Latency Sensitive.
              </para></listitem>
            </varlistentry>
            <varlistentry>
              <term><option>diffserv3</option></term>
              <listitem><para>
                Enables priority queueing based on the Differentiated Service
                (<literal>DiffServ</literal>) field with three tins: Background Traffic, Best Effort,
                and Latency Sensitive.
              </para></listitem>
            </varlistentry>
          </variablelist>

          <para>Defaults to unset, and the kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>FirewallMark=</varname></term>
        <listitem>
          <para>Takes an integer in the range 1…4294967295. When specified, firewall-mark-based
          overriding of CAKE's tin selection is enabled. Defaults to unset, and the kernel's default is
          used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Wash=</varname></term>
        <listitem>
          <para>Takes a boolean value. When true, CAKE clears the DSCP fields, except for ECN bits, of
          any packet passing through CAKE. Defaults to unset, and the kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>SplitGSO=</varname></term>
        <listitem>
          <para>Takes a boolean value. When true, CAKE will split General Segmentation Offload (GSO)
          super-packets into their on-the-wire components and dequeue them individually. Defaults to
          unset, and the kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RTTSec=</varname></term>
        <listitem>
          <para>Specifies the RTT for the filter. Takes a timespan. Typical values are e.g. 100us for
          extremely high-performance 10GigE+ networks like datacentre, 1ms for non-WiFi LAN connections,
          100ms for typical internet connections. Defaults to unset, and the kernel's default will be used.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>AckFilter=</varname></term>
        <listitem>
          <para>Takes a boolean value, or special value <literal>aggressive</literal>. If enabled, ACKs in
          each flow are queued and redundant ACKs to the upstream are dropped. If yes, the filter will always
          keep at least two redundant ACKs in the queue, while in <literal>aggressive</literal> mode, it will
          filter down to a single ACK. This may improve download throughput on links with very asymmetrical
          rate limits. Defaults to unset, and the kernel's default will be used.</para>
        </listitem>
      </varlistentry>

    </variablelist>
  </refsect1>

  <refsect1>
    <title>[ControlledDelay] Section Options</title>
    <para>The [ControlledDelay] section manages the queueing discipline (qdisc) of
    controlled delay (CoDel).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>PacketLimit=</varname></term>
        <listitem>
          <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
          incoming packets are dropped. An unsigned integer in the range 0…4294967294. Defaults to unset and
          kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>TargetSec=</varname></term>
        <listitem>
          <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
          Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IntervalSec=</varname></term>
        <listitem>
          <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
          become too stale. Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>ECN=</varname></term>
        <listitem>
          <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
          unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>CEThresholdSec=</varname></term>
        <listitem>
          <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
          Congestion Experienced (CE). Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[DeficitRoundRobinScheduler] Section Options</title>
    <para>The [DeficitRoundRobinScheduler] section manages the queueing discipline (qdisc) of Deficit Round
    Robin Scheduler (DRR).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[DeficitRoundRobinSchedulerClass] Section Options</title>
    <para>The [DeficitRoundRobinSchedulerClass] section manages the traffic control class of Deficit Round
    Robin Scheduler (DRR).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="tclass-parent" />
      <xi:include href="tc.xml" xpointer="tclass-classid" />

      <varlistentry>
        <term><varname>QuantumBytes=</varname></term>
        <listitem>
          <para>Specifies the amount of bytes a flow is allowed to dequeue before the scheduler moves
          to the next class. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
          Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to the MTU of the
          interface.</para>
        </listitem>
      </varlistentry>

    </variablelist>
  </refsect1>

  <refsect1>
    <title>[EnhancedTransmissionSelection] Section Options</title>
    <para>The [EnhancedTransmissionSelection] section manages the queueing discipline (qdisc) of Enhanced
    Transmission Selection (ETS).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>Bands=</varname></term>
        <listitem>
          <para>Specifies the number of bands. An unsigned integer in the range 1…16. This value has to be at
          least large enough to cover the strict bands specified through the <varname>StrictBands=</varname>
          and bandwidth-sharing bands specified in <varname>QuantumBytes=</varname>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>StrictBands=</varname></term>
        <listitem>
          <para>Specifies the number of bands that should be created in strict mode. An unsigned integer in
          the range 1…16.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>QuantumBytes=</varname></term>
        <listitem>
          <para>Specifies the white-space separated list of quantum used in band-sharing bands. When
          suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
          respectively, to the base of 1024. This setting can be specified multiple times. If an empty
          string is assigned, then the all previous assignments are cleared.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>PriorityMap=</varname></term>
        <listitem>
          <para>The priority map maps the priority of a packet to a band. The argument is a whitespace
          separated list of numbers. The first number indicates which band the packets with priority 0 should
          be put to, the second is for priority 1, and so on. There can be up to 16 numbers in the list. If
          there are fewer, the default band that traffic with one of the unmentioned priorities goes to is
          the last one. Each band number must be in the range 0…255. This setting can be specified multiple
          times. If an empty string is assigned, then the all previous assignments are cleared.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[GenericRandomEarlyDetection] Section Options</title>
    <para>The [GenericRandomEarlyDetection] section manages the queueing discipline (qdisc) of Generic Random
    Early Detection (GRED).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>VirtualQueues=</varname></term>
        <listitem>
          <para>Specifies the number of virtual queues. Takes an integer in the range 1…16. Defaults to unset
          and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>DefaultVirtualQueue=</varname></term>
        <listitem>
          <para>Specifies the number of default virtual queue. This must be less than <varname>VirtualQueue=</varname>.
          Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>GenericRIO=</varname></term>
        <listitem>
          <para>Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to
          unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[FairQueueingControlledDelay] Section Options</title>
    <para>The [FairQueueingControlledDelay] section manages the queueing discipline (qdisc) of fair queuing
    controlled delay (FQ-CoDel).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>PacketLimit=</varname></term>
        <listitem>
          <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
          dropped. Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MemoryLimitBytes=</varname></term>
        <listitem>
          <para>Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance.
          When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
          respectively, to the base of 1024. Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Flows=</varname></term>
        <listitem>
          <para>Specifies the number of flows into which the incoming packets are classified.
          Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>TargetSec=</varname></term>
        <listitem>
          <para>Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay.
          Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>IntervalSec=</varname></term>
        <listitem>
          <para>Takes a timespan. This is used to ensure that the measured minimum delay does not
          become too stale. Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>QuantumBytes=</varname></term>
        <listitem>
          <para>Specifies the number of bytes used as the "deficit" in the fair queuing algorithm timespan.
          When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
          respectively, to the base of 1024. Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>ECN=</varname></term>
        <listitem>
          <para>Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to
          unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>CEThresholdSec=</varname></term>
        <listitem>
          <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
          Congestion Experienced (CE). Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[FairQueueing] Section Options</title>
    <para>The [FairQueueing] section manages the queueing discipline (qdisc) of fair queue traffic policing
    (FQ).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>PacketLimit=</varname></term>
        <listitem>
          <para>Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are
          dropped. Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>FlowLimit=</varname></term>
        <listitem>
          <para>Specifies the hard limit on the maximum number of packets queued per flow. Defaults to
          unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>QuantumBytes=</varname></term>
        <listitem>
          <para>Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed
          to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
          Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to unset and kernel's
          default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>InitialQuantumBytes=</varname></term>
        <listitem>
          <para>Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is
          allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as
          Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to unset and
          kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MaximumRate=</varname></term>
        <listitem>
          <para>Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the
          specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of
          1000. Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Buckets=</varname></term>
        <listitem>
          <para>Specifies the size of the hash table used for flow lookups. Defaults to unset and
          kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>OrphanMask=</varname></term>
        <listitem>
          <para>Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part
          of hash and reduce number of buckets associated with the traffic. Defaults to unset and
          kernel's default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Pacing=</varname></term>
        <listitem>
          <para>Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's
          default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>CEThresholdSec=</varname></term>
        <listitem>
          <para>Takes a timespan. This sets a threshold above which all packets are marked with ECN
          Congestion Experienced (CE). Defaults to unset and kernel's default is used.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[TrivialLinkEqualizer] Section Options</title>
    <para>The [TrivialLinkEqualizer] section manages the queueing discipline (qdisc) of trivial link
    equalizer (teql).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>Id=</varname></term>
        <listitem>
          <para>Specifies the interface ID <literal>N</literal> of teql. Defaults to <literal>0</literal>.
          Note that when teql is used, currently, the module <constant>sch_teql</constant> with
          <constant>max_equalizers=N+1</constant> option must be loaded before
          <command>systemd-networkd</command> is started.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[HierarchyTokenBucket] Section Options</title>
    <para>The [HierarchyTokenBucket] section manages the queueing discipline (qdisc) of hierarchy token
    bucket (htb).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>DefaultClass=</varname></term>
        <listitem>
          <para>Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent
          to the class. Defaults to unset.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>RateToQuantum=</varname></term>
        <listitem>
          <para>Takes an unsigned integer. The DRR quantums are calculated by dividing the value
          configured in <varname>Rate=</varname> by <varname>RateToQuantum=</varname>.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[HierarchyTokenBucketClass] Section Options</title>
    <para>The [HierarchyTokenBucketClass] section manages the traffic control class of hierarchy token bucket
    (htb).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="tclass-parent" />
      <xi:include href="tc.xml" xpointer="tclass-classid" />

      <varlistentry>
        <term><varname>Priority=</varname></term>
        <listitem>
          <para>Specifies the priority of the class. In the round-robin process, classes with the lowest
          priority field are tried for packets first.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>QuantumBytes=</varname></term>
        <listitem>
          <para>Specifies how many bytes to serve from leaf at once. When suffixed with K, M, or G, the
          specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
          1024.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MTUBytes=</varname></term>
        <listitem>
          <para>Specifies the maximum packet size we create. When suffixed with K, M, or G, the specified
          size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>OverheadBytes=</varname></term>
        <listitem>
          <para>Takes an unsigned integer which specifies per-packet size overhead used in rate
          computations. When suffixed with K, M, or G, the specified size is parsed as Kilobytes,
          Megabytes, or Gigabytes, respectively, to the base of 1024.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>Rate=</varname></term>
        <listitem>
          <para>Specifies the maximum rate this class and all its children are guaranteed. When suffixed
          with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively,
          to the base of 1000. This setting is mandatory.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>CeilRate=</varname></term>
        <listitem>
          <para>Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare.
          When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits,
          respectively, to the base of 1000. When unset, the value specified with <varname>Rate=</varname>
          is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>BufferBytes=</varname></term>
        <listitem>
          <para>Specifies the maximum bytes burst which can be accumulated during idle period. When suffixed
          with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively,
          to the base of 1024.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>CeilBufferBytes=</varname></term>
        <listitem>
          <para>Specifies the maximum bytes burst for ceil which can be accumulated during idle period.
          When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes,
          respectively, to the base of 1024.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[HeavyHitterFilter] Section Options</title>
    <para>The [HeavyHitterFilter] section manages the queueing discipline (qdisc) of Heavy Hitter Filter
    (hhf).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />

      <varlistentry>
        <term><varname>PacketLimit=</varname></term>
        <listitem>
          <para>Specifies the hard limit on the queue size in number of packets. When this limit is reached,
          incoming packets are dropped. An unsigned integer in the range 0…4294967294. Defaults to unset and
          kernel's default is used.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[QuickFairQueueing] Section Options</title>
    <para>The [QuickFairQueueing] section manages the queueing discipline (qdisc) of Quick Fair Queueing
    (QFQ).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="qdisc-parent" />
      <xi:include href="tc.xml" xpointer="qdisc-handle" />
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[QuickFairQueueingClass] Section Options</title>
    <para>The [QuickFairQueueingClass] section manages the traffic control class of Quick Fair Queueing
    (qfq).</para>

    <variablelist class='network-directives'>
      <xi:include href="tc.xml" xpointer="tclass-parent" />
      <xi:include href="tc.xml" xpointer="tclass-classid" />

      <varlistentry>
        <term><varname>Weight=</varname></term>
        <listitem>
          <para>Specifies the weight of the class. Takes an integer in the range 1…1023. Defaults to
          unset in which case the kernel default is used.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>MaxPacketBytes=</varname></term>
        <listitem>
          <para>Specifies the maximum packet size in bytes for the class. When suffixed with K, M, or G, the
          specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of
          1024. When unset, the kernel default is used.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>[BridgeVLAN] Section Options</title>
      <para>The [BridgeVLAN] section manages the VLAN ID configuration of a bridge port and accepts the
      following keys. Specify several [BridgeVLAN] sections to configure several VLAN entries. The
      <varname>VLANFiltering=</varname> option has to be enabled, see the [Bridge] section in
      <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>

      <variablelist class='network-directives'>
        <varlistentry>
          <term><varname>VLAN=</varname></term>
          <listitem>
            <para>The VLAN ID allowed on the port. This can be either a single ID or a range M-N. Takes
            an integer in the range 1…4094.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>EgressUntagged=</varname></term>
          <listitem>
            <para>The VLAN ID specified here will be used to untag frames on egress. Configuring
            <varname>EgressUntagged=</varname> implicates the use of <varname>VLAN=</varname> above and will enable the
            VLAN ID for ingress as well. This can be either a single ID or a range M-N.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><varname>PVID=</varname></term>
          <listitem>
            <para>The Port VLAN ID specified here is assigned to all untagged frames at ingress.
            <varname>PVID=</varname> can be used only once. Configuring <varname>PVID=</varname> implicates the use of
            <varname>VLAN=</varname> above and will enable the VLAN ID for ingress as well.</para>
          </listitem>
        </varlistentry>
      </variablelist>
  </refsect1>

  <refsect1>
    <title>Examples</title>
    <example>
      <title>Static network configuration</title>

      <programlisting># /etc/systemd/network/50-static.network
[Match]
Name=enp2s0

[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1</programlisting>

      <para>This brings interface <literal>enp2s0</literal> up with a static address. The
      specified gateway will be used for a default route.</para>
    </example>

    <example>
      <title>DHCP on ethernet links</title>

      <programlisting># /etc/systemd/network/80-dhcp.network
[Match]
Name=en*

[Network]
DHCP=yes</programlisting>

      <para>This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with
      <literal>en</literal> (i.e. ethernet interfaces).</para>
    </example>

    <example>
      <title>IPv6 Prefix Delegation (DHCPv6 PD)</title>

      <programlisting># /etc/systemd/network/55-dhcpv6-pd-upstream.network
[Match]
Name=enp1s0

[Network]
DHCP=ipv6

# The below setting is optional, to also assign an address in the delegated prefix
# to the upstream interface. If not necessary, then comment out the line below and
# the [DHCPPrefixDelegation] section.
DHCPPrefixDelegation=yes

# If the upstream network provides Router Advertisement with Managed bit set,
# then comment out the line below and WithoutRA= setting in the [DHCPv6] section.
IPv6AcceptRA=no

[DHCPv6]
WithoutRA=solicit

[DHCPPrefixDelegation]
UplinkInterface=:self
SubnetId=0
Announce=no</programlisting>

      <programlisting># /etc/systemd/network/55-dhcpv6-pd-downstream.network
[Match]
Name=enp2s0

[Network]
DHCPPrefixDelegation=yes
IPv6SendRA=yes

# It is expected that the host is acting as a router. So, usually it is not
# necessary to receive Router Advertisement from other hosts in the downstream network.
IPv6AcceptRA=no

[DHCPPrefixDelegation]
UplinkInterface=enp1s0
SubnetId=1
Announce=yes</programlisting>

      <para>This will enable DHCPv6-PD on the interface enp1s0 as an upstream interface where the
      DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
      The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
      </para>
    </example>

    <example>
      <title>IPv6 Prefix Delegation (DHCPv4 6RD)</title>

      <programlisting># /etc/systemd/network/55-dhcpv4-6rd-upstream.network
[Match]
Name=enp1s0

[Network]
DHCP=ipv4

# When DHCPv4-6RD is used, the upstream network does not support IPv6.
# Hence, it is not necessary to wait for Router Advertisement, which is enabled by default.
IPv6AcceptRA=no

[DHCPv4]
Use6RD=yes</programlisting>

      <programlisting># /etc/systemd/network/55-dhcpv4-6rd-downstream.network
[Match]
Name=enp2s0

[Network]
DHCPPrefixDelegation=yes
IPv6SendRA=yes

# It is expected that the host is acting as a router. So, usually it is not
# necessary to receive Router Advertisement from other hosts in the downstream network.
IPv6AcceptRA=no

[DHCPPrefixDelegation]
UplinkInterface=enp1s0
SubnetId=1
Announce=yes</programlisting>

      <para>This will enable DHCPv4-6RD on the interface enp1s0 as an upstream interface where the
      DHCPv4 client is running and enp2s0 as a downstream interface where the prefix is delegated to.
      The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network.
      </para>
    </example>

    <example>
      <title>A bridge with two enslaved links</title>

      <programlisting># /etc/systemd/network/25-bridge-static.netdev
[NetDev]
Name=bridge0
Kind=bridge</programlisting>

      <programlisting># /etc/systemd/network/25-bridge-static.network
[Match]
Name=bridge0

[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1
DNS=192.168.0.1</programlisting>

      <programlisting># /etc/systemd/network/25-bridge-slave-interface-1.network
[Match]
Name=enp2s0

[Network]
Bridge=bridge0</programlisting>

      <programlisting># /etc/systemd/network/25-bridge-slave-interface-2.network
[Match]
Name=wlp3s0

[Network]
Bridge=bridge0</programlisting>

      <para>This creates a bridge and attaches devices <literal>enp2s0</literal> and
      <literal>wlp3s0</literal> to it. The bridge will have the specified static address
      and network assigned, and a default route via the specified gateway will be
      added. The specified DNS server will be added to the global list of DNS resolvers.
      </para>
    </example>

    <example>
      <title>Bridge port with VLAN forwarding</title>

      <programlisting>
# /etc/systemd/network/25-bridge-slave-interface-1.network
[Match]
Name=enp2s0

[Network]
Bridge=bridge0

[BridgeVLAN]
VLAN=1-32
PVID=42
EgressUntagged=42

[BridgeVLAN]
VLAN=100-200

[BridgeVLAN]
EgressUntagged=300-400</programlisting>

    <para>This overrides the configuration specified in the previous example for the
    interface <literal>enp2s0</literal>, and enables VLAN on that bridge port. VLAN IDs
    1-32, 42, 100-400 will be allowed. Packets tagged with VLAN IDs 42, 300-400 will be
    untagged when they leave on this interface. Untagged packets which arrive on this
    interface will be assigned VLAN ID 42.</para>
    </example>

    <example>
      <title>Various tunnels</title>

      <programlisting>/etc/systemd/network/25-tunnels.network
[Match]
Name=ens1

[Network]
Tunnel=ipip-tun
Tunnel=sit-tun
Tunnel=gre-tun
Tunnel=vti-tun
      </programlisting>

      <programlisting>/etc/systemd/network/25-tunnel-ipip.netdev
[NetDev]
Name=ipip-tun
Kind=ipip
      </programlisting>

      <programlisting>/etc/systemd/network/25-tunnel-sit.netdev
[NetDev]
Name=sit-tun
Kind=sit
      </programlisting>

      <programlisting>/etc/systemd/network/25-tunnel-gre.netdev
[NetDev]
Name=gre-tun
Kind=gre
      </programlisting>

      <programlisting>/etc/systemd/network/25-tunnel-vti.netdev
[NetDev]
Name=vti-tun
Kind=vti
      </programlisting>

      <para>This will bring interface <literal>ens1</literal> up and create an IPIP tunnel,
      a SIT tunnel, a GRE tunnel, and a VTI tunnel using it.</para>
    </example>

    <example>
      <title>A bond device</title>

      <programlisting># /etc/systemd/network/30-bond1.network
[Match]
Name=bond1

[Network]
DHCP=ipv6
</programlisting>

      <programlisting># /etc/systemd/network/30-bond1.netdev
[NetDev]
Name=bond1
Kind=bond
</programlisting>

      <programlisting># /etc/systemd/network/30-bond1-dev1.network
[Match]
MACAddress=52:54:00:e9:64:41

[Network]
Bond=bond1
</programlisting>

      <programlisting># /etc/systemd/network/30-bond1-dev2.network
[Match]
MACAddress=52:54:00:e9:64:42

[Network]
Bond=bond1
</programlisting>

    <para>This will create a bond device <literal>bond1</literal> and enslave the two
    devices with MAC addresses 52:54:00:e9:64:41 and 52:54:00:e9:64:42 to it. IPv6 DHCP
    will be used to acquire an address.</para>
    </example>

    <example>
      <title>Virtual Routing and Forwarding (VRF)</title>
      <para>Add the <literal>bond1</literal> interface to the VRF master interface
      <literal>vrf1</literal>. This will redirect routes generated on this interface to be
      within the routing table defined during VRF creation. For kernels before 4.8 traffic
      won't be redirected towards the VRFs routing table unless specific ip-rules are added.
      </para>
      <programlisting># /etc/systemd/network/25-vrf.network
[Match]
Name=bond1

[Network]
VRF=vrf1
</programlisting>
    </example>

    <example>
      <title>MacVTap</title>
      <para>This brings up a network interface <literal>macvtap-test</literal>
      and attaches it to <literal>enp0s25</literal>.</para>
      <programlisting># /usr/lib/systemd/network/25-macvtap.network
[Match]
Name=enp0s25

[Network]
MACVTAP=macvtap-test
</programlisting>
    </example>

    <example>
      <title>A Xfrm interface with physical underlying device.</title>

      <programlisting># /etc/systemd/network/27-xfrm.netdev
[NetDev]
Name=xfrm0
Kind=xfrm

[Xfrm]
InterfaceId=7</programlisting>

      <programlisting># /etc/systemd/network/27-eth0.network
[Match]
Name=eth0

[Network]
Xfrm=xfrm0</programlisting>

      <para>This creates a <literal>xfrm0</literal> interface and binds it to the <literal>eth0</literal> device.
      This allows hardware based ipsec offloading to the <literal>eth0</literal> nic.
      If offloading is not needed, xfrm interfaces can be assigned to the <literal>lo</literal> device.
      </para>
    </example>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.link</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.netdev</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-network-generator.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>