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arptables FORWARD chain not working

+2 votes
1,170 views

I tried using arptables on a linux internet gateway to filter out packets that have the source MAC address of the internet connected interface but not its IP address (see below).

I didn't get any hits, although I now there were packets matching the rule. The same rule in the OUTPUT chain works as expected (by me at least) . Is there something else I need to do to use the FORWARD chain?

arptables -I FORWARD 1 -o eth0.164 --source-mac 00:24:E6:00:00:3E -s ! x.x.x.x -j DROP
arptables -I OUTPUT 1 -o eth0.164 --source-mac 00:24:E6:00:00:3E -s ! x.x.x.x -j DROP

posted Dec 24, 2013 by Dewang Chaudhary

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1 Answer

+1 vote

ARP packets generated by the host go through the OUTPUT chain. The FORWARD chain sees only bridged ARP packets, which are received but not generated by the host. Is your gateway acting as a bridge ?

answer Dec 24, 2013 by Meenal Mishra
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