[hobbit] Two DNS lookups for a server but one fails

Johan Sjöberg johan.sjoberg at deltamanagement.se
Thu Jan 8 09:04:50 CET 2009


This night, after installing the new bbtest-net, we received an alarm on bbtest for the Xymon server, saying " - Program crashed Fatal signal caught!"
>From hobbitlaunch.log: "2009-01-08 05:05:07 Task bbnet terminated by signal 6"

/Johan


-----Original Message-----
From: Johan Sjöberg [mailto:johan.sjoberg at deltamanagement.se] 
Sent: den 7 januari 2009 17:01
To: hobbit at hswn.dk
Subject: RE: [hobbit] Two DNS lookups for a server but one fails

Hi.

We have been experiencing another DNS check problem since the upgrade to Xymon 4.2.2. Since I upgraded, I sometimes get "Timeout (channel destroyed) Seconds: 4.999" on two DNS servers that are on an offsite location (connected over VPN). The problem started immediately after the update, so I think it is related. This never happened with 4.2.0. Has the timeout been changed in the new version?
Anyhow, I compiled and installed the new dns.c and have not experienced any "purple" issues. Now I will just wait and see if the DNS check alerts will continue to appear.

/Johan

-----Original Message-----
From: Ward, Martin [mailto:Martin.Ward at colt.net] 
Sent: den 7 januari 2009 16:52
To: hobbit at hswn.dk
Subject: RE: [hobbit] Two DNS lookups for a server but one fails

Hi Henrik,

I compiled that in and installed it but it seems to have messed up all the remote port checks. All my ssh port tests, which are initiated from the server, are now purple, as well as the DNS checks, syslog port checks and others besides.

Rebuilding with the previous version has restored the remote port checks as well as the dual-DNS-check errors.

|\/|artin

> -----Original Message-----
> From: Henrik Størner [mailto:henrik at hswn.dk] 
> Sent: 07 January 2009 13:30
> To: hobbit at hswn.dk
> Subject: Re: [hobbit] Two DNS lookups for a server but one fails
> 
> 
> Hi Martin,
> 
> On Mon, Jan 05, 2009 at 01:58:56PM -0000, Ward, Martin wrote:
> > *** DNS lookup of 'a:smtp.server.com' ***
> > Timeout (channel destroyed)
> > 
> > In this instance it was the A record that failed but in 
> others it is 
> > the NS record. I always get one of the queries back 
> successfully, but 
> > not both.
> > 
> > These were working fine until I upgraded to Xymon 4.2.2 so 
> this looks 
> > like the culprit. Any ideas or suggestions?
> 
> there was a change done in 4.2.2 - backported from the 4.3.x 
> code - to fix a bug that could cause the network tests to 
> lockup while doing the DNS lookups. It is probably that "fix" 
> that causes the problem.
> 
> Going over the DNS code again, I think there's some flawed 
> logic in how it handles the lookups. Could you try the 
> attached version of 
> xymon-4.2.2/bbnet/dns.c ? Just copy it on top of the existing 
> one, then run "make" and copy the resulting 
> xymon-4.2.2/bbnet/bbtest-net 
> binary to your ~xymon/server/bin/ directory (save the 
> existing one just in case this completely breaks stuff).
> 
> 
> Let me know if that is better.
> 
> 
> Regards,
> Henrik
> 
> 


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