[syslog-ng]DNS caching

[Michael Renner]

At 09:01 20.03.2002 +1000, you wrote:
>On Tue, 19 Mar 2002 at 10:24am (+0100), Balazs Scheidler wrote:
>[...]
>
> >
> > can you check this patch, whether it fixes your problem ?
> >
> > diff -u -r1.37 cfgfile.c
> > --- cfgfile.c 2001/09/03 16:42:23     1.37
> > +++ cfgfile.c 2002/03/19 09:23:55
>
>[...]
>
>Thank you... it appears to be working as advertised now.  When running with
>NSCACHE_DEBUG enabled we get lots of messages like...
>
>.... which looks good.  CPU usage for the syslog process has dropped from
>~80% to ~40% (hazzah!) and the named process that was doing local caching
>has dropped from ~10% to almost nill.

Dear Bazsi,

Thanks, also works flawless here, I get hardly any hits on my dnscache. 
Btw. the default option of dns_cache is "on", maybe you should document 
this or change it to "no", otherwise people who upgrade to newer versions 
(with the fixed dns_cache) may be confused by the "new" behaviour of syslog-ng.

You also mention "syslog-ng blocks on DNS queries, so enabling DNS may lead 
to a Denial of Service attack." in your documentation. Does this mean that 
syslog messages which are received by the NIC, while syslog-ng performs a 
synchronous DNS lookup, are stored in the kernels receive buffer or are 
dropped?



best regards,

-- 

Michael Rennner
Junior System Engineer

Inode Telekommunikationsdienstleistungs GmbH - http://www.inode.at
support@inode.at, Tel.: 05 9999-0, Fax.: 05 9999-2699