vlan with its own ether / mac address?

[Brooks Davis]

On Fri, Feb 13, 2004 at 09:30:31PM +0100, Bjorn Eikeland wrote:
> is it possible to set up a vlan device with its own ether address?
> I've tried the following:
> 
> ifconfig vlan0 create
> ifconfig vlan0 vlan 1 vlandev fxp0 up
> ifconfig vlan0 inet 10.0.0.10 netmask 255.255.255.0 \
> 	ether 00:a0:c9:f1:4e:6e
> ifconfig: ether: bad value
> 
> but changing the ether value after the device is up 'works',
> but caused me to only have access to the vlan ip.
> 
> my existing fxp0 device
> fxp0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
>         inet 10.0.0.2 netmask 0xff000000 broadcast 10.255.255.255
>         ether 00:a0:c9:f1:4e:6d
>         media: Ethernet autoselect (100baseTX <full-duplex>)
>         status: active
> 
> the faked vlan0 device:
> vlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
>         inet 10.0.0.10 netmask 0xffffff00 broadcast 10.0.0.255
>         ether 00:a0:c9:f1:4e:6e
>         media: Ethernet autoselect (100baseTX <full-duplex>)
>         status: active
>         vlan: 1 parent interface: fxp0

You might try putting the interface in promisc mode.  I'm not sure that
will be sufficent, but it might be.  I suspect the problem is likely to
be that the recieve filter on many NICs only supports two modes promisc
and self+broadcast.  You want a mode where you get
self1+self2+broadcast.  Some multicast filters probably do support this.

> basically I'm trying to set up dhcp to configure unknown hosts
> in a seperate network to allow them to register their mac address
> and then be allocated a ip in the "real" network. And need a way
> to test with several clients, but I've only got one nic in my box.

You might be able to create virtual ethernet interfaces via tap(4) and
then bridge them.

-- Brooks

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