Re: MAC aliasing

[Claudio Jeker <cjeker_(_at_)_diehard_(_dot_)_n-r-g_(_dot_)_com>]

On Tue, Feb 01, 2005 at 08:31:50PM +0100, Mauro Calderara wrote:
> Hi everyone
> 
> I've a simple problem and not yet a proper solution, maybe someone can 
> give some pointers.
> 
> My cable-provider gives me 4 IPs via DHCP, but only one per MAC. The 
> question is whether it is possible to "fake" MACs on a NIC. Since by 
> concept this is something simple there might be a solution but it is 
> highly possible that I didn't find the right words to feed the search 
> engines.
> 
> Is the idea broken by concept? I know that a MAC is supposed to be 
> unique worldwide, but still it was cool if I could get all IPs. I 
> thought of a workaround but maybe you guys will just shake your heads 
> when reading it, if so, please tell me (and why):
> 
> given that I have 5 NICs in the router, I thought that I could set up a 
> vlan-interface on those not directly connected to the cable-modem (they 
> were supposed to inherit their's parent's MAC, right?) and bridge these 
> vlans to the one NIC attached to the modem. Then I'd just let the dhcp 
> client try to configure them and hope the best. From a firewalling point 
> of view this would probably be not so nice, but I guess that could be 
> worked around with some added complexity to pf.conf to prevent spoofing 
> on those interfaces but that shouldn't be much of a problem as far as I 
> can see. Still it seems a bit hackish and since I don't have PCI-Slots 
> ad infinitum it wouldn't "scale" well when adding another cable-modem :)
> 
> Any pointers, hints & flames appreciated
> 

Never tried it but IIRC carp(4) should use a different MAC.
An other sollution would be to build a bridge(4) with other devices --
tun(4) for example (but I'm not sure if tun(4) works in bridge mode).

-- 
:wq Claudio