[Dovecot] Sometimes Dovecot v1.0.3 does not accept new connections

[Steffen Kaiser]

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Hello,

occasionally Dovecot stops to accept new connections. Already existing 
ones do function properly. Strace'ing dovecot-auth reveals that it is 
running and is authentificating users, the logfile logs new connections. 
However, lots of other connects just stall, before the IMAP server 
responds with the greeting.

My user backend is a LDAP server.

I've sniffed the interface, but I also don't see numerous connection 
attempts, so I suppose, that there is no DoS attack running.

The logfile contains no warning or error except:
dovecot: Oct 17 15:34:44 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:34:49 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:34:52 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:02 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:05 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:12 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:19 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:20 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:25 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:26 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:27 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:27 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:41 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:42 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:47 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:49 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:49 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:50 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:35:56 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048
dovecot: Oct 17 15:36:03 Warning: auth(default): Growing pool 
'plain_auth_request' with: 2048

Does somebody has an idea, where to go to look into the issue?

Bye,

- -- 
Steffen Kaiser
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