[Wlug] iptables use of --mac-source

[Frank Sweetser]

On Fri, Sep 01, 2006 at 10:40:25AM -0400, John Stoffel wrote:
> This will only work if you have a bridged network, once you have a
> switch in the way, the MAC address will change.  This is because

Nope - a switch is logically identical to a bridge with more than two
ports.  A packet forwarded by a router will have the routers MAC address
because the router has to generate a new ethernet frame with the same
ethernet payload as the original packet, while a switch will blindly
forward the packet to wherever it's FDB tells it to.

> For network switches, each port has it's own MAC address.  Basically,

Only if the switch supports spanning tree, and only for spanning tree - those
per-port MACs aren't used for anything else.

-- 
Frank Sweetser fs at wpi.edu  |  For every problem, there is a solution that
WPI Network Engineer          |  is simple, elegant, and wrong. - HL Mencken
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