bridge+netfilter broken for IP fragments in 2.6.16?

From: Thomas Zeitlhofer
Date: Sat Apr 01 2006 - 09:28:24 EST


Hello,

I have set up a bridge with two ports:

# brctl show br0
bridge name bridge id STP enabled interfaces
br0 8000.000021f23d58 no eth1
tap1

Using 2.6.16/.1 non fragmented IP packets are passing the bridge without
problems, but fragmented IP packets do not show up on the outgoing
interface. E.g., for fragmented traffic coming in from tap1 and going
out via eth1 tcpdump shows:

1) on tap1: fragmented packets
2) on br0: the defragmented packet (connection tracking)
3) on eth1: no packet!?

This breaks IPsec connections for example.


Doing the same on 2.6.15.x shows:

1) on tap1: fragmented packets
2) on br0: the defragmented packet (connection tracking)
3) on eth1: fragmented packets

and IPsec connections are ok.


If I disable netfilter for bridged traffic in 2.6.16/.1

# echo 0 > /proc/sys/net/bridge/bridge-nf-call-iptables

then the fragmented traffic passes the bridge without problems.


Is this a known issue?

--
Thomas
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