tcpdump -- non-local traffic not showing

freebsd at freebsd at
Sat Oct 6 00:12:32 PDT 2007

Many thanks; that solved the problem.


> You're probably plugged into a switch ("learning bridge"). Switches
> partition your collision domain -- they learn which MAC is available on
> which port and only send on that port.
> You either need a hub or a really expensive switch (the kind that you
> log in to and set up port mirrors).


> What is your LAN?  My guess is that its a router or a switch.  In either 
> case, the router/switch is not forwarding the packets to all the ports.  
> It retains a table of MAC addresses and the ports they are on.  It only 
> forwards packets to the desired port.  A computer on a different port 
> will not see any of those packets.  You have to use a hub or just a 
> non-learning bridge to get the packets forwarded to all ports.  Those 
> are really hard to find anymore.

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