DNSBL helper not answering

Daniel Gehriger daniel.gehriger@linkcad.com
Thu Nov 23 08:51:37 UTC 2006

Vernon Schryver wrote:
>> From: Daniel Gehriger 
>> I'm running the latest DCC as a postfix before-queue filter, as 
>> described in the SMTPD_PROXY_README.
> When you say "the lastest DCC", do you mean the latest official version
> or the lastest version published by third parties such as Debian?

I'm using DCC 1.3.45-1.55, manually compiled with "./configure 

> Why not set DNSBL_ARGS instead of DCCIFD_ARGS directly?

Ok, I switched to using DNSBL_ARGS with the following parameters (same 
as before in DCCIFD_ARGS):

DNSBL_ARGS="-Bset:debug=5 '-Bset:rej-msg=5.7.1 554 Service unavailable; 
Message (id: %s) blocked using relays.ordb.org; 
http://ordb.org/lookup/?host=%s' -Brelays.ordb.org,any 
'-Bset:rej-msg=5.7.1 554 Service unavailable; Message (id: %s) blocked 
using sbl-xbl.spamhaus.org; http://www.spamhaus.org/query/bl?ip=%s' 

> You must mean dccifd instead of dccproc.

Sorry, yes, I'm using dccifd.

> Are you sure there are no helper processes, and that what is really
> happening is that the relays.ordb.org and sbl-xbl.spamhaus.org DNS
> servers are taking too long to answer?  Have you tried increasing
> the per-URL delay budget with "-Bset:URL-secs=20" or similar?

100% sure. The helper processes (the ones with "-B helper:x,y") exit 
after idling and are not always restarted.

"ps -ef | grep dcc | grep helper" yields nothing.

I already increased the timeout limit w/o success.

> What version and flavor of UNIX-like operating system are you using?
> The main dccifd or dccm process uses waitpid(WNOHANG) to know when
> helper processes have gone away.  That works well on FreeBSD, but
> maybe not on other flavors.
> After every failure to receive an answer from a helper, zombie
> helpers are reaped.
> After 5 failures to receive an answer, all of the helpers are terminated
> and restarted.
> There may be a race in restarting idle helpers.  I'll look into it.

I'm using SuSE Linux 9.1, so that should be fine. I agree that this 
looks like a race condition.

Thanks for looking into this!


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