Re: Help: Marking UDP packets in a bridge

[Vigneswaran R <vignesh@atc.tcs.com>]

On 10/10/2014 08:58 PM, Aravindhan Dhanasekaran wrote:
> Hello,
>
> I'm trying to mark UDP packets entering (or leaving) a bridge, destined to a
> particular UDP port on a machine on the other side of the bridge.
>
> My simple topology looks like:
> host1 [eth1] <-----> [s1-eth1] bridge [s1-eth2] <-----> [eth1] host2
>
>
> I've added a rule to the FORWARD chain on the mangle table in the bridge to mark
> the packets that I require:
> $ sudo iptables -t mangle -A FORWARD -p udp --dport 9917 -j MARK --set-mark 17
> $ iptables -L FORWARD -t mangle -v
> Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
>   pkts bytes target     prot opt in     out     source       destination
>      0     0 MARK       udp  --  any    any     anywhere     anywhere      udp
> dpt:9917 MARK set 0x11
>
>
> But, looks like none of packets are being marked (counters are all 0s in
> iptables output as shown above). I have traffic matching the above rule flowing
> through the bridge which I verified using tcpdump.
> $ sudo tcpdump -i s1-eth1 udp dst port 9917
> ...
> 11:22:14.774417 IP 10.0.0.2.49774 > 10.0.0.1.9917: UDP, length 1470
> 11:22:14.774597 IP 10.0.0.2.49774 > 10.0.0.1.9917: UDP, length 1470
> 11:22:14.774731 IP 10.0.0.2.49774 > 10.0.0.1.9917: UDP, length 1470^C

May be, we should do the packet marking using ebtables (instead of 
iptables) for Ethernet bridge. I am not sure..

vignesh