qmail-smtpd using 100% cpu

[shalako]

qmail-smtpd has been maxing out our server's cpu for hours, either as a single process or split into multiple processes adding up to 100% cpu usage. Other services are becoming non-responsive.

I've read that qmail-smtpd handles incoming mail. Does this mean we're just being blasted with a lot of mail? I've looked at /var/qmail/queue/local and the dirs aren't very big.

What can I do?

 

[gnosis]

Originally posted by shalako
qmail-smtpd has been maxing out our server's cpu for hours, either as a single process or split into multiple processes adding up to 100% cpu usage. Other services are becoming non-responsive.

I've read that qmail-smtpd handles incoming mail. Does this mean we're just being blasted with a lot of mail? I've looked at /var/qmail/queue/local and the dirs aren't very big.

What can I do?

Hi...I'm having this problem too. I've seen several posts on it, but no solutions. So I'm trying to find out if anyone has found a solution.

Thanks,
G

 

[shalako]

I believe we were dealing with a denial-of-service attack on our hosting company. We migrated to a co-lo.

 

[wagnerch]

This isn't very useful information to go on, but it would suggest that either it is a DoS attack or a spammer is using one of your domains to use a "bounce" attack for spamming.

Steps that you can take are to a) investigate the source IP of the attacks and firewall them, and b) use strace and attach to the qmail-smtpd process to see what is happening <perhaps it is looping>

Good luck.

 

[gnosis]

Actually, in my case, it turned out not to be a DoS. I never thought it was, actually, because I could see that smtp connections were not coming in at any inflated rate.

The problem was solved with the help of Mirco - see http://forum.swsoft.com/showthread.php?s=&threadid=40173