Mailscanner / postfix Timeout in the SMTP dialog

[Denis Beauchemin]

Fabien GARZIANO a écrit :
> Hi people !
>
> I think this might not be the right place to ask for this, as it seems
> more like a postfix issue. But that's driving me mad.
> I got this mail relay : 
> Running on
> Linux califw3.caliseo.fr 2.6.16-1.2108_FC4 #1 Thu May 4 23:52:01 EDT
> 2006 i686 i686 i386 GNU/Linux
> This is Fedora Core release 4 (Stentz)
> This is Perl version 5.008006 (5.8.6)
>
> This is MailScanner version 4.53.8
>
> And postfix 2.2.2
>
> Some time ago, I found that some of the incoming SMTP connections were
> interrupted with this kind of message : 
> postfix/smtpd[12529]: timeout after DATA from host.domain.ext[x.x.x.x]
>
> And this seems more and more frequent. Some googling drove me to some
> MTU or network troubleshoot which didn't solve anything (I've tried to
> lower MTU or even to raise it, the server is in a DMZ behind a FW and
> next is the ISP router).
> I've checked everything outside the mail server (Firewall, network) but
> I came to the conclusion that the problem was coming for the server.
>
> Once again, I know this might not be the right place for what I guess is
> a pure Postfix issue (as it happens during SMTP exchange), but if anyone
> here have experienced the same behaviour, I would be happy to hear about
> it.
>
> I also guess I'll have to update the whole server cause it's now quite
> old (postfix, MailScanner, etc...).
>
> Thanks.
>   
Fabien,

I don't know it this applies to you but I had to apply the following 
patch to my kernel setup on RHEL 5 to stop that knid of problems:
tail /etc/sysctl.conf
# Fix for tcp window scaling issue related to broken Internet routers
net.ipv4.tcp_wmem = 4096 16384 131072
net.ipv4.tcp_rmem = 4096 87380 174760

# From S. Freegard fsl.com
# increase Linux autotuning TCP buffer limits
# min, default, and max number of bytes to use
#net.ipv4.tcp_rmem = 4096 87380 16777216
#net.ipv4.tcp_wmem = 4096 65536 16777216

I also included the values Steeve Freegard is using.  You will have to 
restart your server after modifying your sysctl.conf file (or you could 
use the sysctl command to make the changes dynamically).

Denis

-- 
   _
  °v°   Denis Beauchemin, analyste
 /(_)\  Université de Sherbrooke, S.T.I.
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