--On January 9, 2006 11:02:12 AM -0600 [EMAIL PROTECTED] wrote:
During high load (about 18 imapd logins/second from a webmail system) we
start to get long delays when connecting to port 143. Sometimes, even a
connection refused when attempted from outside localhost. Delays
possibly range from 20 seconds to 2 minutes. When telneting to port 143
from localhost, the delays are evident before the IMAP capabilities logo
splashes. After IMAP's banner is shown, everything seems fine. It's
before getting the banner that lags.
Are you using tcp wrappers (tcpd) for imap? Might it be configured to do
either ident or reverse DNS lookups? I'm guessing that either a firewall
is dropping the ident queries rather than sending a TCP reset, or
something's funky about the reverse lookup.
The quickest way to test this theory is to eliminate tcp wrappers from
inetd.conf on the imap line, and see if the problem instantly goes away.
The quickest non-disruptive way to test this theory is to sniff the
traffic.
Mark
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