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I'm in a corporate environment with a DHCP server with static assignments for my server. I have one physical nic with several sub-interfaces. I statically assign different MAC addresses for each sub-interface to get another IP address from the DHCP server. For some reason, my server is not taking the static MAC addresses. You'll notice that ifconfig shows each interface with the same MAC.

How do I assign unique MAC addresses to my sub-interfaces?

$ cat interfaces

auto lo 
iface lo inet loopback

auto eth0:1
iface eth0:1 inet dhcp 
        hwaddress ether 00:0c:29:31:24:fa
        hostname gwrt-test
        client gwrt-test

auto eth0:2
iface eth0:2 inet dhcp
        hwaddress ether 00:0c:29:31:25:fa
        hostname gwrt-test2
        client gwrt-test2

$ ifconfig

eth0      Link encap:Ethernet  HWaddr 00:0c:29:31:25:fa  
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:329737 errors:0 dropped:0 overruns:0 frame:0
          TX packets:121645 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:69228791 (69.2 MB)  TX bytes:63531749 (63.5 MB)
          Interrupt:16 

eth0:1    Link encap:Ethernet  HWaddr 00:0c:29:31:25:fa  <- should be 24:fa
          inet addr:10.203.102.29  Bcast:10.203.102.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:16 

eth0:2    Link encap:Ethernet  HWaddr 00:0c:29:31:25:fa  
          inet addr:10.203.102.32  Bcast:10.203.102.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:16
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If you're thinking of going to the trouble of setting the MAC address explicitly for each interface, and as you say the addresses handed out by the dhcp server are static and reserved for use by your server, why not just configure them statically instead of using dhcp? –  roadmr Nov 4 '13 at 18:29
    
Company politics. The server is for development and sitting on my desk... but yes, static would be ideal. –  Jason Tooke Nov 4 '13 at 19:35

2 Answers 2

You can install macchanger Install macchanger

Then execute like following,

sudo macchanger --mac 00:11:22:33:44:55 <interface_name>

More details

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Multimac can do this. (http://www.primianotucci.com/os/multimac) Alternatively you can use "ip link" to add veth interfaces.

In both methods you must then bridge veth0 to eth0 using brctl (bridge-utils).

Each interface (tapX for multimac or vethX for veth) can then have custom mac addresses (ifconfig hw ether xx:xx:xx:xx:xx:xx, interface should be down.)

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