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Date: Thu, 13 Mar 2008 15:49:27 +0000 (UTC)
From: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net>
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To: Mike Silbersack <silby@silby.com>
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Cc: freebsd-net@freebsd.org, "d.s. al coda" <coda.trigger@gmail.com>
Subject: Re: TCP options order changed in FreeBSD 7, incompatible with some
 routers
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On Wed, 12 Mar 2008, Mike Silbersack wrote:

>
> On Wed, 12 Mar 2008, Mike Silbersack wrote:
>
>> I think we will need to fix tcpdump before trying to finish diagnosing this 
>> problem.  We were missing key information before.
>> 
>> -Mike
>
> Hm, that was far easier than expected.  Patch attached.
>
> Here's what the two tcpdumps show now:
>
> 6.3:
> IP A > B : S 2575736483:2575736483(0) ack 1762868649 win 65535 <mss 
> 1460,sackOK,eol,eol>
>
> 7.0:
> IP A > B : S 3304309835:3304309835(0) ack 710421411 win 65535 <mss 
> 1380,sackOK,eol,nop>
>
> That makes the problem quite a bit more clear.  Anyone working on this issue 
> should apply this patch ASAP.

what do you think of this version?

http://sources.zabbadoz.net/freebsd/patchset/20080313-01-tcpdump-print-tcp-option-padding.diff


It should give you output like this:

<mss 1396,nop,wscale 3,nop,nop,timestamp 3321226304 19549200,sackOK,eol,0x01[bad padding]>
<mss 1396,nop,wscale 3,nop,nop,timestamp 574483947 19641135,sackOK,eol,0x00>
<mss 1430,sackOK,timestamp 723328502 20006573,nop,wscale 6>


-- 
Bjoern A. Zeeb                                 bzeeb at Zabbadoz dot NeT
Software is harder than hardware  so better get it right the first time.