[boysimple]

I know it's possible to add a second IP address to an ethernet port - is the same possible with an airport card?

The Network PrefPane interface doesn't let you create duplicates of the airport, but it does for ethernet. Possibly a forbear of bad news.

Using ifconfig, I added an alias to my airport card:

udo ifconfig en1 alias 192.168.1.50 netmask 255.255.255.0

Which makes the IP show up:

Code:
en1: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        inet6 fe80::230:65ff:fe24:94b8%en1 prefixlen 64 scopeid 0x5 
        inet 192.168.1.2 netmask 0xffffff00 broadcast 192.168.1.255
        inet 192.168.1.50 netmask 0xffffff00 broadcast 192.168.1.255
        ether 00:30:65:24:94:b8 
        media: autoselect status: active
        supported media: autoselect

But it doesn't seem to "work" eg - the added ip doesn't ping from other compters on the network, but the original IP pings just fine.

Am I going down a dead end?

E

[BkueKanoodle]

My understanding of this is that when you assign a second ip address to your ethernet card, OS X assigns it a virtual MAC (media access control, not macintosh ) address. The 802.11b protocol does not allow for a wireless card to spoof a second mac address and thus it can not be assigned a separate IP address.

As an example, virtual pc allows you to set a unique ip address to one of your guest os, but it does this by using the same mac address. This is the Virtual switch technology they tout in their advertisements. Unfortunately, it is their proprietary technology and they don't want to share.