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Newsgroups: mail-lists.delegate-en

[DeleGate-En] Delegate: Invalid DNS name causes infinite loop
22 Apr 2006 17:36:35 GMT Snow <pnygabdyi-mnhipgc4s5jr.ml@ml.delegate.org>


Hi,

If a computer's name has an underscore in it (eg bad_name.domain.co.uk),
then resolving it will sometimes cause Delegate to go into an infinite
loop and stop answering requests.  The loop doesn't use lots of CPU, but
you can see it happening in the the log; maybe it's making requests to
itself? It seems to be something to do with IPv6, but there is no IPv6
on the network.

Delegate runs on the same machine as the client apps and it is setup as
the machine's default DNS resolver.

I can't reproduce the problem on-demand, but it occurs 1-2 times a day
with a single-user and medium/heavy network use. When it does occur the
underscore is replaced by a colon in the logs...

eg  bad_name.domain.co.uk becomes bad:name.domain.co.uk

...and then it starts looping; recursively prefixing "-AAAA" in front of
the domain.

04/19 17:37:57.70 [1036] 1+31: {R} QUERY (0)
-AAAA.-AAAA.-AAAA.-AAAA.bad:name.domain.co.uk IN AAAA ID=15071
04/19 17:38:04.66 [3140] 1+38: {R} ANSWER
Q[-AAAA.-AAAA.bad:name.domain.co.uk] ID=31962/31962 AA=1 RD=1 RA=0
RCODE=3 ans,ns,add=0,0,0 [ID=19]
04/19 17:38:04.66 [3140] 1+38: [60.297s] 127.0.0.1:1026 ID=31962

I run delegate with:

HOSTLIST=local-hosts:{*,!-*.*,*.domain.co.uk,*.domain.com}
HOSTLIST=local-dns:192.168.161.3
HOSTLIST=external-dns:192.168.3.1,62.241.162.200,62.241.163.201
SERVER=dns
RESOLV=cache,file:hosts,dns:local-dns:local-hosts,dns:external-dns:{*,!*.domain.co.uk}
TIMEOUT=dns:2
DNSCONF=para:5
-P53


Environment:
  Delegate 9.1.1
  WinXp+sp2
  Delegate resolver-proxy and client-apps on same machine
  Windows networking DNS:
    eth0 (LAN):
      primary: 127.0.0.1
      secondary: 192.168.161.3
    eth1 (VPN):
      primary: 127.0.0.1
      secondary: 192.168.3.1
  192.168.161.3 resolves internal names correctly
                and times-out for external names
  192.168.3.1 resolves external names correctly
              and resolves internal names incorrectly.

The real logs and my bat file can be downloaded from (222kb):

http://www.snow.vg/stuff/dg-logs.zip

Thanks.

-- 
Snow


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