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Re: MAC aliasing
- To: misc_(_at_)_openbsd_(_dot_)_org
- Subject: Re: MAC aliasing
- From: Mauro Calderara <mcalderara_(_at_)_phys_(_dot_)_ethz_(_dot_)_ch>
- Date: Wed, 2 Feb 2005 16:05:30 +0100
On Feb 2, 2005, at 2:45 PM, m christensen wrote:
Claudio Jeker wrote:
So, why not just connect 4 NICs to the cable modem?
On Tue, Feb 01, 2005 at 08:31:50PM +0100, Mauro Calderara wrote:
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
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).
Cheap single NICs can be had for 5 bucks and I've seen multi port
cards for ~30 in the past,
if slots are a problem.
yeah, that would solve the problem, too. in Switzerland singleport NICs
aren't quite as cheap AFAICT but still affordable. Multiport is way
beyond 180sFr (120euro?) ... but you are right, it might be the only
solution. I'll try the trick with the vlans even tough no one commented
it, if it doesn't work and diana's virtual-thing isn't out then, I'll
have to go for a multiport NIC.
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