Re: [fw-wiz] Multiple MAC address on one interface

From: Harald Welte (
Date: 07/10/04

  • Next message: Jason: "Re: [fw-wiz] Multiple MAC address on one interface"
    Date: Sat, 10 Jul 2004 22:11:51 +0200

    On Fri, Jul 09, 2004 at 09:16:31PM -0400, wrote:
    > So, is there some cheap way to have one NIC
    > respond to multiple MAC addresses? I'm most comfortable with Linux, but
    > if I needed to use BSD or something else I'd be willing to do that.

    Unfortunately this is not supported straight away by a stock kernel. So
    there are two ways

    1) use layer2 source-nat of the ebtables bridging tools (didn't test it

    2) add the 2nd, 3rd, ... mac addresses to the multicast filter of your
       NIC. Even though the multicast filters are thought for multicast MAC
       addresses, they work fine with unicast MAC addresses, too ;) However,
       I am not aware of any userspace tools to do so... the function inside
       the kernel is dev_mc_add().

    This remembers me to that fact that I always wanted to implement
    something like 'real' alias devices... where eth0:0 can have a different
    mac address than eth0:1 (which is not the case right now).

    > </chris>

    - Harald Welte <>     
    Programming is like sex: One mistake and you have to support it your lifetime

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