Date: Tue, 4 Nov 2008 01:38:00 -0800 From: Jeremy Chadwick <koitsu@FreeBSD.org> To: Matthias Kellermann <mk@adminlife.net> Cc: freebsd-pf@freebsd.org Subject: Re: rdr rule does not work (bad hdr length) Message-ID: <20081104093800.GA43676@icarus.home.lan> In-Reply-To: <491012AE.7000409@adminlife.net> References: <491012AE.7000409@adminlife.net>
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On Tue, Nov 04, 2008 at 10:15:26AM +0100, Matthias Kellermann wrote: > Hi list, > > I'm trying to set up a simple rdr rule in pf (7.0-RELEASE-p5). > > I have two hosts - host a (192.168.0.250) and host b (192.168.0.10) - in > a local network and want to forward one port from host a to host b. > > host a is the pf host. This is the rule to redirect traffic from host a > to b: > > rdr proto tcp from any to 192.168.0.250 port 23 -> 192.168.0.10 > pass log (all) proto tcp from any to 192.168.0.10 port 23 synproxy state > > If I try to get a telnet connection from my client 192.168.0.51 the > connection gets stuck and nothing happens. This is the output of tcpdump > on the pflog0 interface: > > # tcpdump -netttvvi pflog0 > 000000 rule 0/0(match): pass in on sis0: (tos 0x10, ttl 64, id 26668, > offset 0, flags [DF], proto TCP (6), length 60) 192.168.0.51.54460 > > 192.168.0.10.23: [|tcp] > 000266 rule 0/0(match): pass out on sis0: (tos 0x10, ttl 64, id 25527, > offset 0, flags [DF], proto TCP (6), length 44) 192.168.0.51.54460 > > 192.168.0.10.23: tcp 24 [bad hdr length 0 - too short, < 20] > > Anybody has an idea whats wrong here? This is not a pf problem. tcpdump's snaplen defaults to 56 bytes, which is too small when reading from pflog. Use the -s flag to increase the snaplen to 256 bytes, for example. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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