Date: Tue, 26 Nov 2002 11:17:56 -0800 (PST) From: Julian Elischer <julian@elischer.org> To: Don Bowman <don@sandvine.com> Cc: "'freebsd-net@freebsd.org'" <freebsd-net@freebsd.org> Subject: Re: IPFW question with options and fwd rule Message-ID: <Pine.BSF.4.21.0211261113360.52749-100000@InterJet.elischer.org> In-Reply-To: <FE045D4D9F7AED4CBFF1B3B813C853370102303E@mail.sandvine.com>
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On Tue, 26 Nov 2002, Don Bowman wrote: > > If I create a rule to 'fwd' packets with a particular TCP option > set (or IP option) to a specific local port, and then I accept > on that port, will subsequent packets without that option work? > > ie, I have this: > > 100 fwd localhost,9000 tcp from any to any 1234 tcpoptions ts recv interface > > SYN (TCP option SACK=1), Dest port=5555, Dest ip = random-host > SYN/ACK > ACK (no TCP options) > > will the first SYN reach me? (yes I think, even though the IP is not mine > and well, no, because 5555 != 1234 :-) but, assuming that your rule said 5555, then it would only reach you if it has the ts option set. to be forwarded a packet must match teh rule.. subsequent packewts must ALSO match the rule. you could use dynamic rules to match subsequent packets I think, but I've never used them. > the dest port is not me, the ipfw fwd magic takes care). > Will the ACK from the client reach me? (the dest ip is not me, so will the > stack discard, or will the already created PCB take care of this?) > > I'd like to carry on a normal TCP conversation, but select the local port > that terminates it based on a TCP option. The destination IP will be > somewhere > else (its a transparent proxy application). > > Thanks in advance. > > --don (don@sandvine.com www.sandvine.com) > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-net" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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