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Change MAC Addresses of Network Interfaces
There are rare situations where the modification of MAC addresses are extremely useful, e.g. when performing network based development or networks administration.
This article illustrates how to modify MAC addresses of hard wired ethernet interfaces and wireless LAN interfaces when utilizing IP networks.
Contents
Basics
Every network interface has a unique hardware address preconfigured. This address is availabe to the local operation system and remote systems communicating with/via your local network interface. The predefined hardware address is called MAC address.
There are a number of scenarios where you are required to modify your local MAC address.
Please note that modifying MAC addresses is not supported by every network interface and not all bit permutations are allowed to be set.
Before changing the MAC address of network interfaces make sure that you feel certain what you are doing and what (legal) consequences are involved with this step – especially in corporate networks!
Modify MAC Addresses
The following three simple steps are required to perform the reconfiguration.
- bring down the desired network interface
- set the new MAC address
- reactivate the network interface
If you did choose a valid MAC address and your device supports the reconfiguration of MAC addresses then you are done. There is nothing else to do!
The following sections describe what commands are required to perform the reconfiguration by utilizing some real world examples.
Ethernet Devices
The following command line session illustrates how to reconfigure your local ethernet device.
# print a list of running network devices $ ifconfig eth0 Link encap:Ethernet HWaddr e0:cb:33:44:aa:bb UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Interrupt:46 [...] # now we did decide to reconfigure eth0, so # bring down the interface eth0 $ sudo ifconfig eth0 down # set the new MAC address $ sudo ifconfig eth0 hw ether 02:01:02:03:ee:ff # restart the interface $ sudo ifconfig eth0 up # show list of devices $ ifconfig eth0 Link encap:Ethernet HWaddr 02:01:02:03:ee:ff UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Interrupt:46 [...]
WLAN Devices
The reconfiguration of wireless LAN devices works the same way as described before! Take a look at the following command line session, where the device wlan0 is going to be reconfigured.
# print a list of running network devices $ ifconfig [...] wlan0 Link encap:Ethernet HWaddr 00:25:d3:ff:33:77 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:27000 errors:0 dropped:0 overruns:0 frame:0 TX packets:20556 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:27410368 (27.4 MB) TX bytes:3017865 (3.0 MB) [...] # now we did decide to reconfigure wlan0, so # bring down the interface wlan0 $ sudo ifconfig wlan0 down # set the new MAC address $ sudo ifconfig wlan0 hw ether 00:22:02:03:04:08 # restart the interface $ sudo ifconfig wlan0 up # show list of devices $ ifconfig [...] wlan0 Link encap:Ethernet HWaddr 00:22:02:03:04:08 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:27000 errors:0 dropped:0 overruns:0 frame:0 TX packets:20556 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:27410368 (27.4 MB) TX bytes:3017865 (3.0 MB) [...]