Multiple MAC addresses on one NIC

Hello Everyone.
My ISP assigns static IP addresses using DHCP (I know - how can they be
static when they're assigned? Trust me, there is no other way for us to do
this.) only to registered MAC addresses and we can only get one IP per MAC
address. For reasons that are entirely vaild, we need to assign two
Internet IPs to a single NIC.

I can easily do IP aliasing with eth1:0, eth1:1, etc - but haw can we change
the MAC address of one of the aliased devices without changing the others on
the same physical device? We've tried "ifconfig eth1:1 hw ether
00:01:02:03:04:05" but this changes MACs for all eth1 aliases.

Allan Wingenbach
awingenbachATtelusDOTnet.nospamfor.me

Allan Wingenbach wrote:

> I can easily do IP aliasing with eth1:0, eth1:1, etc - but haw can we
> change the MAC address of one of the aliased devices without changing the
> others on
> the same physical device? We've tried "ifconfig eth1:1 hw ether
> 00:01:02:03:04:05" but this changes MACs for all eth1 aliases.
>

As far as I know, there's no way to do that.

--

Fundamentalism is fundamentally wrong.

To reply to this message, replace everything to the left of "@" with
james.knott.

"Allan Wingenbach" <(E-Mail Removed)> said:
>Hello Everyone.
>My ISP assigns static IP addresses using DHCP (I know - how can they be
>static when they're assigned? Trust me, there is no other way for us to do
>this.) only to registered MAC addresses and we can only get one IP per MAC
>address. For reasons that are entirely vaild, we need to assign two
>Internet IPs to a single NIC.

Is it MAC address, or will DHCP client identifier do?
Some DHCP clients allow setting the DHCP client identifier, and thus will
allow several IPs on a single interface by DHCP (so, on some DHCP servers,
DHCP client identifier is the key information).
--
Wolf a.k.a. Juha Laiho Espoo, Finland
(GC 3.0) GIT d- s+: a C++ ULSH++++$ P++@ L+++ E- W+$@ N++ !K w !O !M V
PS(+) PE Y+ PGP(+) t- 5 !X R !tv b+ !DI D G e+ h---- r+++ y++++
"...cancel my subscription to the resurrection!" (Jim Morrison)

It has to be MAC address. This is the only method of obtaining an IP from
our ISP.

Allan

"Juha Laiho" <(E-Mail Removed)> wrote in message
news:c7qp3j$tin$(E-Mail Removed)-int...
> "Allan Wingenbach" <(E-Mail Removed)> said:
> >Hello Everyone.
> >My ISP assigns static IP addresses using DHCP (I know - how can they be
> >static when they're assigned? Trust me, there is no other way for us to
do
> >this.) only to registered MAC addresses and we can only get one IP per
MAC
> >address. For reasons that are entirely vaild, we need to assign two
> >Internet IPs to a single NIC.
>
> Is it MAC address, or will DHCP client identifier do?
> Some DHCP clients allow setting the DHCP client identifier, and thus will
> allow several IPs on a single interface by DHCP (so, on some DHCP servers,
> DHCP client identifier is the key information).
> --
> Wolf a.k.a. Juha Laiho Espoo, Finland
> (GC 3.0) GIT d- s+: a C++ ULSH++++$ P++@ L+++ E- W+$@ N++ !K w !O !M V
> PS(+) PE Y+ PGP(+) t- 5 !X R !tv b+ !DI D G e+ h---- r+++ y++++
> "...cancel my subscription to the resurrection!" (Jim Morrison)

On Mon, 10 May 2004 20:31:12 GMT, Allan Wingenbach <(E-Mail Removed)> wrote:
> Hello Everyone.
> My ISP assigns static IP addresses using DHCP (I know - how can they be
> static when they're assigned? Trust me, there is no other way for us to do
> this.) only to registered MAC addresses and we can only get one IP per MAC
> address. For reasons that are entirely vaild, we need to assign two
> Internet IPs to a single NIC.

> I can easily do IP aliasing with eth1:0, eth1:1, etc - but haw can we change
> the MAC address of one of the aliased devices without changing the others on
> the same physical device? We've tried "ifconfig eth1:1 hw ether
> 00:01:02:03:04:05" but this changes MACs for all eth1 aliases.

AFAIK, only two possibilities:
1. Second NIC in the same machine, which means you'd need a hub or
switch to connect to the ISP modem.
2. Get a different ISP.

Good luck!

--
Dale Dellutri <(E-Mail Removed)> (lose the Q's)

"Dale Dellutri" <(E-Mail Removed)> wrote in message
news:c7telu$hfk$(E-Mail Removed)...
> On Mon, 10 May 2004 20:31:12 GMT, Allan Wingenbach <(E-Mail Removed)> wrote:
> > Hello Everyone.
> > My ISP assigns static IP addresses using DHCP (I know - how can they be
> > static when they're assigned? Trust me, there is no other way for us to
do
> > this.) only to registered MAC addresses and we can only get one IP per
MAC
> > address. For reasons that are entirely vaild, we need to assign two
> > Internet IPs to a single NIC.
>
> > I can easily do IP aliasing with eth1:0, eth1:1, etc - but haw can we
change
> > the MAC address of one of the aliased devices without changing the
others on
> > the same physical device? We've tried "ifconfig eth1:1 hw ether
> > 00:01:02:03:04:05" but this changes MACs for all eth1 aliases.
>
> AFAIK, only two possibilities:
> 1. Second NIC in the same machine, which means you'd need a hub or
> switch to connect to the ISP modem.
> 2. Get a different ISP.
>
> Good luck!
>
> --
> Dale Dellutri <(E-Mail Removed)> (lose the Q's)

If I understand the question correctly, what you are doing is really
no different that having 2 computer connected. Get a cheap router
that does dhcp and let its MAC address be the registered one. In
fact, if it's a hassle to change the registered MAC address with the
ISP, most routers today let you clone an existing (perhaps already
registered) MAC address in the router. Then you can do whatever
you want to on your side of the router.

Let us know how this all works out.
--
Herb Stein
(E-Mail Removed)

"Allan Wingenbach" <(E-Mail Removed)> wrote in message news:<kERnc.21132$F04.15497@clgrps13>...
> Hello Everyone.
> My ISP assigns static IP addresses using DHCP (I know - how can they be
> static when they're assigned? Trust me, there is no other way for us to do
> this.) only to registered MAC addresses and we can only get one IP per MAC
> address. For reasons that are entirely vaild, we need to assign two
> Internet IPs to a single NIC.
>
> I can easily do IP aliasing with eth1:0, eth1:1, etc - but haw can we change
> the MAC address of one of the aliased devices without changing the others on
> the same physical device? We've tried "ifconfig eth1:1 hw ether
> 00:01:02:03:04:05" but this changes MACs for all eth1 aliases.
>

I just took a look at ifconfig.c from http://www.tazenda.demon.co.uk/phil/net-tools

Anyone know what we'd have to edit in ifconfig.c to make

"ifconfig eth1:1 hw ether 00:01:02:03:04:05"

work for aliases?

On 12 May 2004 21:52:25 -0700, bazzz777 <(E-Mail Removed)> wrote:
> "Allan Wingenbach" <(E-Mail Removed)> wrote in message news:<kERnc.21132$F04.15497@clgrps13>...
> > Hello Everyone.
> > My ISP assigns static IP addresses using DHCP (I know - how can they be
> > static when they're assigned? Trust me, there is no other way for us to do
> > this.) only to registered MAC addresses and we can only get one IP per MAC
> > address. For reasons that are entirely vaild, we need to assign two
> > Internet IPs to a single NIC.
> >
> > I can easily do IP aliasing with eth1:0, eth1:1, etc - but haw can we change
> > the MAC address of one of the aliased devices without changing the others on
> > the same physical device? We've tried "ifconfig eth1:1 hw ether
> > 00:01:02:03:04:05" but this changes MACs for all eth1 aliases.
> >
> I just took a look at ifconfig.c from http://www.tazenda.demon.co.uk/phil/net-tools
> Anyone know what we'd have to edit in ifconfig.c to make
> "ifconfig eth1:1 hw ether 00:01:02:03:04:05"
> work for aliases?

I think that resetting the MAC address modifies the NIC, and the NIC
can only present one MAC address on the wire. Further, the
presentation of the MAC address happens at the physical link layer, so
the software can set it (by modifying the NIC), but not control it.

So there's no way to do this with one NIC.

I think.

--
Dale Dellutri <(E-Mail Removed)> (lose the Q's)

El Mon, 10 May 2004 20:31:12 GMT "Allan Wingenbach" <(E-Mail Removed)>
escribió:

> Hello Everyone.
> My ISP assigns static IP addresses using DHCP (I know - how can they
> be static when they're assigned? Trust me, there is no other way for
> us to do this.) only to registered MAC addresses and we can only get
> one IP per MAC address. For reasons that are entirely vaild, we need
> to assign two Internet IPs to a single NIC.
>
> I can easily do IP aliasing with eth1:0, eth1:1, etc - but haw can we
> change the MAC address of one of the aliased devices without changing
> the others on the same physical device? We've tried "ifconfig eth1:1
> hw ether 00:01:02:03:04:05" but this changes MACs for all eth1
> aliases.

I'm not an expert on these things, but anyway, here are my thoughts
about:

- aliasing works at a "logical level", handling IP addresses

- the MAC address is a hardware issue. The ethernet card must have a
unique MAC address in order to know which packets are directed to it,
and to identify itself to other cards (say, for reply purposes) at the
ethernet transport level (¿am i saying stupid things?)

- the only way to "simulate" an ethernet card with multiple MAC
addresses (AFAIK) will be to switch it to "promiscuous mode"
(i.e., tell it to accept all packets) and make the software handle
them, and also handle by software the source MAC addresses of the
packates going out

- no idea if there are applications to do this, others than hacking with
tools for diagnostics, spoofing and the like

- should i have such a problem, i will surely go for a router, so i will
have a different MAC on every interface, then route and mangle the
packets as appropiate by configuring NAT in the router

--
Gonzalo Pérez de Olaguer Córdoba <(E-Mail Removed)>
PGP key 2861C704 --- F206 5671 6789 425D 111C 1302 214F 1934 2861 C704

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