Date: Fri, 06 Feb 2004 20:11:33 -0500 From: "Louis A. Mamakos" <louie@TransSys.COM> To: Thomas Vogt <turbo23@gmx.net> Cc: freebsd-ipfw@freebsd.org Subject: Re: ipfw2/dummynet set new mss on thy fly Message-ID: <200402070111.i171BX0R019173@whizzo.transsys.com> In-Reply-To: Your message of "Sat, 07 Feb 2004 01:28:25 %2B0100." <40243129.7060400@gmx.net> References: <40243129.7060400@gmx.net>
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Can't you write a rule that only diverts packets with the SYN bit set? It's the only time a TCP MSS option is allowed to be set. It doesn't seem like there's any reason to send all the traffic through tcpmssd. (And the problem isn't a "wrong" windows implementation, it's broken Path MTU discovery due to overzelous filtering of ICMP.) louie > Hi > > Is it possible to modify the mss with ipfw2/dummynet? This is necessary > to fix wrong window implementations for example for adsl providers. > > Something like "modify mss=1452 tcp from any to any out recv em0 xmit > em1 tcpflags syn". (Of course this string is wrong, it's just to give > you an impression). > > I know there is tcpmssd port but it uses divert. I've to modify every > packet on gigabit lan (at least 200mb/s traffic). So tcpmssd is a bit to > slow. > > We already have a ipfw1 patch and It's not that difficult to port it to > ipfw2. But I'm not sure if ipfw2/dummynet already have something similar > implemented by default. > Any hints? > > cheers, > Thomas > _______________________________________________ > freebsd-ipfw@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-ipfw > To unsubscribe, send any mail to "freebsd-ipfw-unsubscribe@freebsd.org"
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