FreeBSD bridge + filtering, BIG problem

Clément MOULIN cmoulin at simplerezo.com
Wed Dec 1 05:21:03 PST 2004


Pyun YongHyeon wrote:
>Both pf and ipf can't create *states* in bridge mode. That restriction
comes from bridge(4). Since pf/ipf couldn't create states it will drop the
packet when it thinks the packet is in out of TCP window.
>
>If you want to use pf/ipf in bridge mode, don't use stateful inspection.
>One more note: filtering works only for inbound traffics in bridge mode.


If you're right, it SHOULD really be specified in bridge(4), but I'm not
very sure about this, since I see states with pfctl and no packets are
dropped in my case (except maybe in scp from internet to sr01) !

Finally, I have found the main problem. Both for ipf/pf, I have to set
sysctl "net.link.ether.bridge.ipf" to 1... That does'nt exists on FreeBSD
4X. After that, incoming traffic is filtered (accounting works, blocking
rules too).
We REALLY need to specify this in FreeBSD handbook (sections 14.9 -
firewalls and 24.5.4 - bridging) and Migration Guide of 5X, since it could
be a big security hole.

My last problem is that scping from sr01 to internet that stalled after
144KB exactly (internet to sr01 works) ! This is a pf issue, since it occurs
only when pf is enabled.


--
Clement Moulin
SimpleRezo - Simplifiez-vous le reseau !
Web: http://www.simplerezo.com/




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