Setting tcp_keepalive_time option [Was: Client hanging up : problem found]

[Andrzej Filip]

Ghislain ADNET wrote:
> Hi,
> 
>  I have solved the problem i had with the client hanging trouble on our 
> new cyrus imapd server.
> 
>  The problem is not cyrus related but i share here so other can benefit 
> from my story.
> 
> Symptom:
> 
>  Client hang after some time, the connexion time out and the server 
> close the connection because of "too much idle time".
>  All fiddling with timeout and idle settings on the server do not change 
> a thing.
> 
> Solution:
> 
>  Our server as in front of it a firewall that was in "allow All" to the 
> imap and from the imap server. BUT some firewalls even if you tell them 
> to not touch anything concerning the traffic still shutdown any 
> connections after some amount of time. In our case you have to click in 
> the advance tab where we found a "timeout"  and change the timeout from 
> 5 to 31 minutes.
> 
>   This solved every problem we had. So what we learned in that is : 
> Don't assume anything, telling all is open do not mean on all firewalls 
> that he must not touch the traffic for this case and you have to review 
> ALL the settings it offer :-)
> 
>  I hope this can help some people :)

One way to fix it "at cyrus level" is to implement per tcp service 
tcp_keepalive_time tcp socket option. The default 2h is (IMHO) to long 
for busy server.

-- 
Andrzej [en:Andrew] Adam Filip anfi at priv.onet.pl anfi at xl.wp.pl
http://anfi.homeunix.net/ http://slashdot.org/~anfi
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