Date: Tue, 13 Nov 2007 07:50:53 +0530 From: Girish Venkatachalam <girishvenkatachalam@gmail.com> To: freebsd-questions@freebsd.org Subject: Re: PF, bridge, states and window scaling problem Message-ID: <20071113022053.GA17768@saraswathy.susmita.org> In-Reply-To: <669132de0711121208n32bfb827p4984c6d3383da713@mail.gmail.com> References: <669132de0711121208n32bfb827p4984c6d3383da713@mail.gmail.com>
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On 22:08:03 Nov 12, Alupului Costin wrote: > I seem to have quite a problem with PF. I have set up a bridge to > shape my upstream traffic. I use ALTQ with hfsc discipline; but that's > not really important. My problem comes with the filter rules. I have > to use keep state because of the speed benefits (really I don't have a > choice), One should always keep state. > but PF has a problem when the clients passing traffic through > the bridge use TCP window scaling. Here is an example of four filter > rules that I thought should work to pass the traffic from one client > through the bridge and create a state: > > pass in quick on vlan0 from any to anIP/32 > pass out quick on vlan0 from anIP/32 to any keep state queue ul_client > pass in quick on vlan1 from anIP/32 to any > pass out quick on vlan1 from any to anIP/32 keep state queue dl_client > > The above rules generate state-mismatches. Didn't get you. What sort of mismatch? > I thought that would be > because pf doesn't see the SYN packet, although it does (one of the > out rules) and should create the state then... I tried writing all the > rules with keep state (even the inbound ones) but then nothing would > work at all. My intention was to create if-bound states, but I > switched back to floating states in the hope that pf would associate > the state created by an outbound rule with the traffic returning on > another interface of the bridge; still didn't work. > Have you tried adding "flags S/SAFR" to the filter rules? Try it and let me know. > I have read the man page for if_bridge and set the following sysctl variables: > > net.link.bridge.pfil_onlyip: 1 > net.link.bridge.pfil_bridge: 0 > net.link.bridge.pfil_member: 1 > > I have also read some posts on the web that said that pf simply > doesn't have all the hooks necesary to do the filtering inbound and > outbound, but reading the pfil man page I seem to disaggree with that. > What do you mean? ? > Has anyone encountered the same problem? And, more important: if i > give up the bridge setup and switch to routing, would that have any > effect? I.E: will I then be able to use keep state with the inbound > rules? Try it. Routing changes the topology a good deal. But I doubt if that is the issue here. No harm in testing though. > > Any help at all would be hugely appreciated as I am trying for about a > week to sort out this problem and can't seem to get any closer. The > only solution was to kindly ask my clients using TCP window scaling > (Vista mostly) to turn off this feature... Now I am seriously > considering bumping my bridge to a router but I am not sure that the > problem will be solved then. Try adding the flags switch as mentioned above. That way the states get established only from a TCP Syn packet. You should also try flushing the old states using pfctl(8). > > Oh, here is the setup of the bridge from rc.conf, although there > shouldn't be any problems there (the bridge works fine without pf, or > with pf stateless): Stateful filtering is always recommended. Performance is not the only reason why you should use it. It also adds to security. Have you tried disabling normalization/scrub? Best, Girish
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