Subject: disabling "switching" functionality in bridge(4)?
To: None <>
From: Hubert Feyrer <>
List: tech-net
Date: 02/27/2005 00:19:48
I have setup bridge(4) to connect an ethernet interface and two tap(4) 
devices. The two tap devices are connected to two seperate qemu processes.
Now when I send packets from one qemu to another, I'd like to analyse that 
traffic by running tcpdump on the ethernet address (or from somewhere 
else outside the two qemu processes).

This doesn't work, as bridge(4) is smart enough to learn MAC addresses, 
and only forward to the right "port", not all of them (i.e. it's 
operating as a switch, not hub).

Now my question is, is there some way to disable this fine switching 
behaviour, and make it behave like a dumb hub?
Or allow adding some "mirror" port?
Or even giving the bridge device an IP number, and run tcpdump on that?

  - Hubert

NetBSD - Free AND Open!      (And of course secure, portable, yadda yadda)