Re: Connection reset by peer - TCP window size oddity ?

[Stephen Hemminger <shemminger@osdl.org>]

On Mon, 03 Oct 2005 15:44:13 +0100
Graham Murray <graham@gmurray.org.uk> wrote:

> Martin Drallew <m.drallew@fatsquirrel.org> writes:
> 
> > A tcpdump follows and, unless I'm misunderstanding the output (quite
> > possible) it looks like the kernel is sending outside of the peer's
> > TCP window, to which the peer responds by resetting the connection.
> 
> I think that you have overlooked one detail in the output. Both
> systems have declared window scaling of 2, so when otter sets the
> window size of 1984 in the packet it is actually advertising a window
> of 7936, which you are not exceeding. You do not say what type of
> system otter is (or what OS it is running), so one explanation is that
> otter has just mirrored your 'wscale 2' in its SYN-ACK without
> actually meaning it.

So you have a firewall in between the systems? There have been firewall's
that strip off the window size option, and this causes all sorts of
nasty problems like this.

-- 
Stephen Hemminger <shemminger@osdl.org>
OSDL http://developer.osdl.org/~shemminger