Date: Mon, 15 Jun 1998 10:43:15 -0700 (PDT) From: Julian Elischer <julian@whistle.com> To: Hans Zuidam <hans@brandinnovators.com> Cc: John Polstra <jdp@polstra.com>, hackers@FreeBSD.ORG Subject: Re: TCP sequence numbers Message-ID: <Pine.BSF.3.95.980615104201.7513D-100000@current1.whistle.com> In-Reply-To: <199806150637.IAA11326@truk.brandinnovators.com>
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you could use ipfw and ipdivert to divert one particular machine's packets into a sequence-number translator.. basically the same as natd but only fiddling sequence numbers julian On Mon, 15 Jun 1998, Hans Zuidam wrote: > > John Polstra wrote: > > In article <199806120831.KAA00529@truk.brandinnovators.com>, > > Hans Zuidam <hans@brandinnovators.com> wrote: > > > For a particularly nasty TCP problem I have with an embedded target > > > I would like to have the ability to always use the same initial > > > sequence number on a particular connection. It would make it easier > > > to compare tcpdump traces. > > Are you sure? Tcpdump prints TCP sequence numbers in relative form, > > relative to the initial one, unless you give it the "-S" option. Your > > traces should match already, except for the initial packet from each > > side. > But the other side cannot "tcpdump", it's an embedded system from > which I can only get absolute sequence numbers ;-( Also, trpt(8) > dumps it's sequence numbers in abosolute (hex) numbers, that's easy > to change. > > It's probably easier to have TCP use the same initial sequence > number instead of modifying other programs. To add predictable > sequence numbers I am thinking to add a TCP option for setsockopt(3) > to set an initial sequence number. Maybe a sysctl could be added > to turn the feature globally on or off. > > Regards, > Hans > > -- > H. Zuidam E-Mail: hans@brandinnovators.com > Brand Innovators B.V. P-Mail: P.O. Box 1377 > de Pinckart 54 5602 BJ Eindhoven, The Netherlands > 5674 CC Nuenen Tel. +31 40 2631134, Fax. +31 40 2831138 > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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