Re: [exim] Ports

On Mon, 2010-08-16 at 17:46 -0700, Brent Jones wrote:
> I guess I should clarify, ICMP 'types'. :)
>
> I've seen rare situations where PMTUD breaks past a firewall that
> blocks all ICMP types. But I've tested with all ICMP blocked and only
> under certain situations where the remote side found an odd MTU would
> it break. But it could very well likely happen more often than that in
> the wild.

Anyone using PPPoE will have such an 'odd MTU'. That includes a *lot* of
cable and ADSL users.

It's extremely common to find PMTU black holes where some idiot has
decided it would be clever to block ICMP without really understanding
what they're doing.

--
dwmw2