[Bridge] Sending 802.1Q packets using AF_PACKET socket on filtered bridge forwards with wrong MAC addresses
Brandon Carpenter
brandon.carpenter at cypherpath.com
Tue Nov 28 17:21:17 UTC 2017
While attempting to send ARP DAD packets on a bridge device, I noticed
that hosts attached to the bridge ports were not responding. After
digging in with tcpdump/wireshark, I noticed that the MAC addresses of
the packets (the first 12 bytes of the Ethernet frame) were wrong and
were an exact duplicate of the following 12 bytes (bytes 13-24), but
only on slave bridge ports. The bridge device itself had the correct
addresses. Here is an example setup:
> # ip link add br0 type bridge vlan_filtering 1
--
Brandon Carpenter | Software Engineer
Cypherpath, Inc.
400 Columbia Point Drive Ste 101 | Richland, Washington USA
Office: (650) 713-3060
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