diff options
Diffstat (limited to 'libnet/sample/gre.c')
| -rw-r--r-- | libnet/sample/gre.c | 410 |
1 files changed, 410 insertions, 0 deletions
diff --git a/libnet/sample/gre.c b/libnet/sample/gre.c new file mode 100644 index 0000000..fb203b8 --- /dev/null +++ b/libnet/sample/gre.c @@ -0,0 +1,410 @@ +/* + * + * libnet 1.1 + * Build a GRE packet + * To view: tcpdump -s 0 -n -X -vvv proto gre + * + * Copyright (c) 2003 Frédéric Raynal <pappy@security-labs.org> + * All rights reserved. + * + * + * KNOWN BUG + * the encapsulated headers have wrong checksums. I guess this is due to + * the one pass libnet_pblock_coalesce() which is really to complicated :( + * + * + * Default packet: + * # ./gre -d 1.2.3.4 + * libnet 1.1 packet shaping: GRE 1701 [link] + * Wrote 78 byte GRE packet; check the wire. + * + * 18:58:12.112157 192.168.1.2 > 1.2.3.4: gre 198.35.123.50.1234 > 103.69.139.107.53: S [bad tcp cksum 698a!] 16843009:16843009(0) win 32767 (ttl 64, id 242, len 40, bad cksum 0!) (ttl 255, id 255, len 64) + * 0x0000 4500 0040 00ff 0000 ff2f f4df c0a8 0102 E..@...../...... + * 0x0010 0102 0304 0000 0800 4500 0028 00f2 0000 ........E..(.... + * 0x0020 4006 0000 c623 7b32 6745 8b6b 04d2 0035 @....#{2gE.k...5 + * 0x0030 0101 0101 0202 0202 5002 7fff 6666 0000 ........P...ff.. + * + * Packet with a computed checksum + * # ./gre -d 1.2.3.4 -c 0 + * libnet 1.1 packet shaping: GRE 1701 [link] + * Wrote 82 byte GRE packet; check the wire. + * + * 18:58:22.587513 192.168.1.2 > 1.2.3.4: gre [Cv0] C:7c62 198.35.123.50.1234 > 103.69.139.107.53: S [bad tcp cksum 698a!] 16843009:16843009(0) win 32767 (ttl 64, id 242, len 40, bad cksum 0!) (ttl 255, id 255, len 68) + * 0x0000 4500 0044 00ff 0000 ff2f f4db c0a8 0102 E..D...../...... + * 0x0010 0102 0304 8000 0800 7c62 0000 4500 0028 ........|b..E..( + * 0x0020 00f2 0000 4006 0000 c623 7b32 6745 8b6b ....@....#{2gE.k + * 0x0030 04d2 0035 0101 0101 0202 0202 5002 7fff ...5........P... + * 0x0040 6666 0000 ff.. + * + * + * Packet with a forced checksum + * # ./gre -d 1.2.3.4 -c 6666 + * libnet 1.1 packet shaping: GRE 1701 [link] + * Wrote 68 byte GRE packet; check the wire. + * + * 19:04:12.108080 192.168.1.2 > 1.2.3.4: gre [Cv0] C:1a0a 198.35.123.50.1234 > 103.69.139.107.53: S [bad tcp cksum 698a!] 16843009:16843009(0) win 32767 (ttl 64, id 242, len 40, bad cksum 0!) (ttl 255, id 255, len 68) + * 0x0000 4500 0044 00ff 0000 ff2f f4db c0a8 0102 E..D...../...... + * 0x0010 0102 0304 8000 0800 1a0a 0000 4500 0028 ............E..( + * 0x0020 00f2 0000 4006 0000 c623 7b32 6745 8b6b ....@....#{2gE.k + * 0x0030 04d2 0035 0101 0101 0202 0202 5002 7fff ...5........P... + * 0x0040 6666 0000 ff.. + * + * + * + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + */ + +#if (HAVE_CONFIG_H) +#include "../include/config.h" +#endif +#include "./libnet_test.h" + + +void +usage(char *prog) +{ + fprintf(stderr, "Usage: %s\n", prog); + fprintf(stderr, "\t IP options: -d <dst ip> [-s src ip]\n"); + fprintf(stderr, "\t GRE options: [-v] set RFC 2637 mode (PPP in GRE) (default is RFC 1701 for IP in GRE)\n"); + fprintf(stderr, "\t\t RFC 1701 options (IP in GRE):\n"); + fprintf(stderr, "\t\t [-c sum] [-r routing] [-k key] [-n seqnum]\n"); + fprintf(stderr, "\t\t IP in GRE options: [-S src ip] [-D dst ip]\n"); + fprintf(stderr, "\t\t RFC 2637 options (PPP in GRE):\n"); + fprintf(stderr, "\t\t [-a ack]\n"); + + exit(1); +} + +/* + * --------------------------------- + * | Delivery Header | + * --------------------------------- + * | GRE Header | + * --------------------------------- + * | Payload packet | + * --------------------------------- + */ +int +main(int argc, char *argv[]) +{ + char c; + libnet_t *l; + char errbuf[LIBNET_ERRBUF_SIZE]; + u_long src_ip = 0, dst_ip = 0, gre_src_ip = 0, gre_dst_ip = 0; + u_short checksum = 0, offset = 0; + u_char *routing = NULL; + u_long key = 0, seq = 0; + u_short gre_flags = 0; + u_long len; + u_long size = 0; + libnet_ptag_t t; + + printf("libnet 1.1 packet shaping: GRE [link]\n"); + + /* + * Initialize the library. Root priviledges are required. + */ + l = libnet_init( + LIBNET_LINK, /* injection type */ + NULL, /* network interface */ + errbuf); /* error buffer */ + + if (!l) + { + fprintf(stderr, "libnet_init: %s", errbuf); + exit(EXIT_FAILURE); + } + + /* + * parse options + */ + while ((c = getopt(argc, argv, "d:s:D:S:c:r:k:n:va:")) != EOF) + { + switch (c) + { + + case 'd': + if ((dst_ip = libnet_name2addr4(l, optarg, LIBNET_RESOLVE)) == -1) + { + fprintf(stderr, "Bad destination IP address: %s\n", optarg); + exit(EXIT_FAILURE); + } + break; + case 's': + if ((src_ip = libnet_name2addr4(l, optarg, LIBNET_RESOLVE)) == -1) + { + fprintf(stderr, "Bad source IP address: %s\n", optarg); + exit(EXIT_FAILURE); + } + break; + case 'D': + if ((gre_dst_ip = libnet_name2addr4(l, optarg, LIBNET_RESOLVE)) == -1) + { + fprintf(stderr, "Bad destination IP address (GRE): %s\n", optarg); + exit(EXIT_FAILURE); + } + break; + case 'S': + if ((gre_src_ip = libnet_name2addr4(l, optarg, LIBNET_RESOLVE)) == -1) + { + fprintf(stderr, "Bad source IP address (GRE): %s\n", optarg); + exit(EXIT_FAILURE); + } + break; + case 'c': + checksum = atoi(optarg); + gre_flags|=GRE_CSUM; + break; + case 'r': + routing = optarg; + gre_flags|=GRE_ROUTING; + break; + case 'k': + key = atoi(optarg); + gre_flags|=GRE_KEY; + break; + case 'n': + seq = atoi(optarg); + gre_flags|=GRE_SEQ; + break; + case 'v': + gre_flags|=(GRE_VERSION_1|GRE_KEY); + break; + case 'a': + if (! (gre_flags & GRE_VERSION_1)) + usage(argv[0]); + seq = atoi(optarg); /* seq in v0 is ack in v1 */ + gre_flags|=GRE_ACK; + break; + default: + exit(EXIT_FAILURE); + } + } + + /* + * check options + */ + if (!dst_ip) + { + usage(argv[0]); + } + + if (!src_ip) + { + src_ip = libnet_get_ipaddr4(l); + } + + if (!gre_dst_ip) + { + gre_dst_ip = libnet_get_prand(LIBNET_PRu32); + } + + if (!gre_src_ip) + { + gre_src_ip = libnet_get_prand(LIBNET_PRu32); + } + + + if ( (gre_flags & GRE_VERSION_MASK) == 0) + { + /* + * Build a TCP/IP packet embedded in GRE message + */ + size = LIBNET_TCP_H; + t = libnet_build_tcp( + 1234, /* source port */ + 53, /* destination port */ + 0x01010101, /* sequence number */ + 0x02020202, /* acknowledgement num */ + TH_SYN, /* control flags */ + 32767, /* window size */ + 0, /* checksum */ + 0, /* urgent pointer */ + size, /* TCP packet size */ + NULL, /* payload */ + 0, /* payload size */ + l, /* libnet handle */ + 0); /* libnet id */ + if (t == -1) + { + fprintf(stderr, "Can't build TCP header (GRE): %s\n", libnet_geterror(l)); + goto bad; + } + + size += LIBNET_IPV4_H; + t = libnet_build_ipv4( + size, /* length */ + 0, /* TOS */ + 242, /* IP ID */ + 0, /* IP Frag */ + 64, /* TTL */ + IPPROTO_TCP, /* protocol */ + 0, /* checksum */ + gre_src_ip, /* source IP */ + gre_dst_ip, /* destination IP */ + NULL, /* payload */ + 0, /* payload size */ + l, /* libnet handle */ + 0); /* libnet id */ + if (t == -1) + { + fprintf(stderr, "Can't build IP header (GRE): %s\n", libnet_geterror(l)); + goto bad; + } + } + + if ( (gre_flags & GRE_VERSION_MASK) == 1) + { + offset = libnet_get_prand(LIBNET_PRu16); + if (~gre_flags & GRE_ACK) + { + u_char ppp[4] = "\x00\x01"; /* PPP padding */ + checksum = 2; /* checksum is in fact payload_s in PPP/GRE (v1) */ + size = 2; + gre_flags|=GRE_SEQ; + key = libnet_get_prand(LIBNET_PRu32); + + /* + * Build a PPP packet embedded in GRE message + */ + t = libnet_build_data( + ppp, + checksum, + l, + 0 + ); + if (t == -1) + { + fprintf(stderr, "Can't build PPP header (GRE): %s\n", libnet_geterror(l)); + goto bad; + } + } + gre_flags&=~(GRE_CSUM|GRE_ROUTING); + } + + /* + * Build the GRE message + */ + if (gre_flags & GRE_ROUTING) + { + /* as packet are stacked, start by the last one, ie null sre */ + size += LIBNET_GRE_SRE_H; + t = libnet_build_gre_last_sre(l, 0); + if (t == -1) + { + fprintf(stderr, "Can't build GRE last SRE header: %s\n", libnet_geterror(l)); + goto bad; + } + size += LIBNET_GRE_SRE_H + strlen(routing); + t = libnet_build_gre_sre( + GRE_IP, /* address family */ + 0, /* offset */ + strlen(routing), /* routing length */ + routing, /* routing info */ + NULL, /* payload */ + 0, /* payload size */ + l, /* libnet handle */ + 0); /* libnet id */ + if (t == -1) + { + fprintf(stderr, "Can't build GRE last SRE header: %s\n", libnet_geterror(l)); + goto bad; + } + } + + len = libnet_getgre_length(gre_flags); + size += len; + t = libnet_build_gre( + gre_flags, /* flags & version */ + (gre_flags & GRE_VERSION_1 ? GRE_PPP : GRE_IP), /* type */ + checksum, /* v0: checksum / v1: payload_s */ + offset, /* v0: offset / v1: callID */ + key, /* v0: key / v1: seq bum */ + seq, /* v0: seq num / v1: ack */ + size, /* length */ + NULL, /* payload */ + 0, /* payload size */ + l, /* libnet handle */ + 0); /* libnet id */ + if (t == -1) + { + fprintf(stderr, "Can't build GRE header: %s\n", libnet_geterror(l)); + goto bad; + } + + + /* + * Build the "real" IP header + */ + size+=LIBNET_IPV4_H; + t = libnet_build_ipv4( + size, /* length */ + 0, /* TOS */ + 255, /* IP ID */ + 0, /* IP Frag */ + 255, /* TTL */ + IPPROTO_GRE, /* protocol */ + 0, /* checksum */ + src_ip, /* source IP */ + dst_ip, /* destination IP */ + NULL, /* payload */ + 0, /* payload size */ + l, /* libnet handle */ + 0); /* libnet id */ + if (t == -1) + { + fprintf(stderr, "Can't build IP header (GRE): %s\n", libnet_geterror(l)); + goto bad; + } + + t = libnet_autobuild_ethernet( + "11:11:11:11:11:11", /* ethernet destination */ + ETHERTYPE_IP, /* protocol type */ + l); /* libnet handle */ + if (t == -1) + { + fprintf(stderr, "Can't build ethernet header: %s\n", + libnet_geterror(l)); + goto bad; + } + /* + * Write it to the wire. + */ + + c = libnet_write(l); + if (c == -1) + { + fprintf(stderr, "Write error: %s\n", libnet_geterror(l)); + goto bad; + } + else + { + fprintf(stderr, "Wrote %d byte GRE packet; check the wire.\n", c); + } + libnet_destroy(l); + return (EXIT_SUCCESS); +bad: + libnet_destroy(l); + return (EXIT_FAILURE); +} |