import of dnsmasq-2.39.tar.gzv2.39

1 files changed, 21 insertions, 0 deletions

diff --git a/FAQ b/FAQ
index 279b6e8..cb74994 100644
--- a/FAQ
+++ b/FAQ
@@ -409,6 +409,27 @@ A: Yes, as a DNS server, dnsmasq will just work in a vserver.
    refer to the vserver documentation for more information).
 
 
+Q: What's the problem with syslog and dnsmasq?
+
+A: In almost all cases: none. If you have the normal arrangement with
+   local daemons logging to a local syslog, which then writes to disk,
+   then there's never a problem. If you use network logging, then
+   there's a potential problem with deadlock: the syslog daemon will
+   do DNS lookups so that it can log the source of log messages,
+   these lookups will (depending on exact configuration) go through
+   dnsmasq, which also sends log messages. With bad timing, you can 
+   arrive at a situation where syslog is waiting for dnsmasq, and
+   dnsmasq is waiting for syslog; they will both wait forever. This
+   problem is fixed from dnsmasq-2.39, which introduces asynchronous
+   logging: dnsmasq no longer waits for syslog and the deadlock is
+   broken. There is a remaining problem in 2.39, where "log-queries"
+   is in use. In this case most DNS queries generate two log lines, if
+   these go to a syslog which is doing a DNS lookup for each log line,
+   then those queries will in turn generate two more log lines, and a 
+   chain reaction runaway will occur. To avoid this, use syslog-ng
+   and turn on syslog-ng's dns-cache function.
+
+