Date: Thu, 25 Jul 2002 01:55:49 -0500 (CDT) From: Mike Silbersack <silby@silby.com> To: Alex Dyas <alexdyas@hotmail.com> Cc: net@freebsd.org Subject: Re: BSD / Firewall / 0 window size problem Message-ID: <20020725014935.R18906-100000@patrocles.silby.com> In-Reply-To: <F181w037NqMPbYquXUR00018f80@hotmail.com>
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On Tue, 23 Jul 2002, Alex Dyas wrote: > Attached are two more tcpdumps, client.txt being the client side of a > problematic session, server.txt being the server side of the same session. > Both machines in this case are BSD. The thing to note in these dumps is > what you suggested, ie the 0 sized window can only be seen on the client > side, NOT on the server side. So as you say, the problem seems to be being > introduced by the GNAT box. WHOO! COOKIE FOR SILBY! > I've been suspecting the GNAT box all along. BSD->Any_other_machine > connections have no problem. Unfortunately I don't admin it, and don't (yet) > know enough about it to debug such a thing. The guy who does points out that > we have never seen the problem in anything other than BSD clients. > > A guess, but could it be that other clients (Windows/Linux etc) are in some > way more tolerant of such problems? Not knowing very much at all about NAT, > what would I look for in debugging such a problem on the GNAT box, as I can > probably get a look at it? > > Thanks again for the help. I'm learning a lot here. > > Alex.. Yes, linux would actually ignore that 0 window update. I recently talked over linux's algorithm for accepting window updates and was thinking of importing it for other reasons. This looks like just one more reason that I should actually post a patch which does so. There's clearly something wrong with the nat system, but I have this suspicion that it'll be faster to patch all the FreeBSD systems with the patch (which I'll be lazy about and take a while to post) than to wait for a fix for the nat software to be released. :) Mike "Silby" Silbersack To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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