Stephen S. Kelley writes:
or time out, new ones are once again available. There were no new
incoming esmtp connections in the log for a day and a half after the
spam storm when the server was rebooted and lots of mail piled up on
secondary servers during this time.
Does esmptd permanently refuse connections after reaching a limit?
No.
Could the couriertcpd process listening on port 25 have crashed or got
messed up? Could 75 esmtpd processes somehow got stuck preventing new
ones from starting?
couriertcpd is pretty resilient. I have a SMP box here also running Red Hat
8.0. Unfortunately, it looks like the latest Red Hat kernels definitely
have stability issues at high load.
Check your syslog, for kernel messages that read something like
'array.c:407: bad pmd c001e30f', with varying hexadecimal numbers. If you
logged those prior to the system hanging, it's a known bug where some
processes get frozen under high system load (while others processes continue
to get CPU slices normally). Red Hat bug #70003.
6 messages in net.sourceforge.lists.courier-users[courier-users] Re: Esmtp ddos vulner...