> On Jul 28, 2015, at 21:52 , Steffan Cline <[email protected]> wrote:
>
> Ok, I think I have come a little further.
>
> When dovecot stops accepting connections, I checked netstat and found this:
>
> [root@hosting1 ~]# netstat -an | grep 993
> tcp 0 0 0.0.0.0:993 0.0.0.0:*
> LISTEN
> tcp 0 0 65.39.x.x:993 184.101.x.x:36351
> SYN_RECV
> tcp 0 0 65.39.x.x:993 107.212.x.x:51487
> SYN_RECV
> tcp 0 0 65.39.x.x:993 107.212.x.x:51488
> SYN_RECV
> tcp 0 0 65.39.x.x:993 184.101.x.x:44650
> SYN_RECV
>
> This told me it wasn’t too many connections causing dovecot to be
> unresponsive. So then I tried via telnet.
>
> Dovecot seems to accept connections but then just sits there and does
> nothing. I used the appropriate commands to try and initiate a login but
> nothing happens. Typing any commands at all produce no response from dovecot.
Actually, I think the above shows that it’s not a dovecot problem. A socket
in a SYN_RECV state means that a connection request has been merely been
received from the network. That means your kernel has not finished
establishing the TCP connection, so dovecot (or the application level in
general) is likely not even involved yet. I would suspect some sort of
firewall config on your host, or perhaps some sort of overload at the network
stack level. But, the latter only if the server were very heavily loaded.
I hope this feedback is helpful.
- Chris
