[sclug] Bizarre IMAP problem

[Alex Butcher]

On Wed, 24 Aug 2005, Roland Turner (SCLUG) wrote:

> Darren Davison wrote:
>> * 1 FETCH (BODY[TEXT]
>>
>> ..and that's it.  Always at that exact point, the connection dries up
>> and
>
>
> Sounds something like a PMTU problem, particularly given that there's a
> VPN involved.

Good call. I should have spotted this too, given how many times it was my
first fix for calls logged with me in a previous life...

> A quick test for this is to force the initial segment size
> down on the Linux side with something like "ifconfig eth0 mtu 1000" before
> any TCP connections are established. If this works, look for firewall
> stupidity somewhere.

Even better, ifconfig eth0 mtu 576, which is the largest MTU that is
guaranteed to traverse any and all types of network without fragmentation.

> - Raz

Best Regards,
Alex.
-- 
Alex Butcher      Brainbench MVP for Internet Security: www.brainbench.com
Bristol, UK                      Need reliable and secure network systems?
PGP/GnuPG ID:0x271fd950                         <http://www.assursys.com/>