[ALUG] Re: Re: TCP Problem *NOT* routing (was: Wierd routing/DNS problem)

[Brett Parker]

On Fri, Oct 06, 2006 at 09:33:06AM +0100, cl at isbd.net wrote:
> On Fri, Oct 06, 2006 at 09:10:33AM +0100, Brett Parker wrote:
> > On Fri, Oct 06, 2006 at 08:46:40AM +0100, cl at isbd.net wrote:
> > > Do ping and traceroute use UDP?  If so it would seem that UDP is
> > > working OK but that TCP isn't.
> > 
> > Ping is ICMP, traceroute is UDP, grab tcptraceroute... if that doesn't
> > work then you've got a TCP problem, this is *not* routing, though, as
> > ICMP and UDP can traverse, this limits it to a firewall, and I'd assume
> > that it's your gateway device.
> > 
> The gateway is a router, already in use by two or three other systems
> on the network with no problems.  That was my first thought in fact so
> I checked that the router firewall setup was the same for the new
> Linux box as for the other systems - it is.

OK - alarm bells just went off in my head... just a simple, really easy
question here... is this a 2.6.17 kernel? If so, can you try the
following:
        echo 0 > /proc/sys/net/ipv4/tcp_window_scaling

If your networking then works, I know what the problem is... if not,
then there's something else at play here ;)

Cheers,
-- 
Brett Parker