How to change MAC-address of Ethernet card

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Sometimes changing MAC-address of a network card is needed. For example, when it used for authorisation by internet provider. This is relatively simple yet unobvious in a first time procedure, but here are some examples.



Temporary MAC-address change
Go to the terminal and type:

sudo ifconfig eth0 hw ether xx:xx:Xx:xx

and MAC-address change and will stay until reboot. If you wish to change MAC-address permanently, you need to do this:


Permanent change of MAC-address
In Debian, for example, go to  /etc/network/if-pre-up.d/ and create file from root named pre-up.
Let`s write to them strings like this:

#! /bin/sh

ifconfig eth0 hw ether 00:00:00:00

Change zeroes by needed MAC-address. To make changes active immediately, restart of network subsystem is required:

/etc/init.d/networking restart

In first time, following diagnostic messages are expected to appear:

# /etc/init.d/networking restart
Setting up IP spoofing protection: rp_filter.
Reconfiguring network interfaces...SIOCDELRT: No such process
ifup: interface lo already configured
SIOCSIFHWADDR: Device or resource busy
run-parts: /etc/network/if-pre-up.d/pre-up exited with return code 1
done.

No problems, repeat command, and it will execute smoother:

notebeast:/home/beast# /etc/init.d/networking restart
Setting up IP spoofing protection: rp_filter.
Reconfiguring network interfaces...ifup: interface lo already configured
done.

Here we go, the MAC-address is changed permanently.


How to find out MAC-address of network card in Linux
It's very simple, just type:

sudo ifconfig

and you see something like this:

eth0 Link encap:Ethernet HWaddr 00:0A:E4:53:AA:2D
inet addr:10.26.49.77 Bcast:10.26.63.255 Mask:255.255.240.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:208554 errors:0 dropped:0 overruns:0 frame:0
TX packets:125071 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:40664531 (38.7 MiB) TX bytes:45919980 (43.7 MiB)
Interrupt:21 Base address:0x4c00

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:18511 errors:0 dropped:0 overruns:0 frame:0
TX packets:18511 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:537155 (524.5 KiB) TX bytes:537155 (524.5 KiB)

One's MAC-address is emphased by red font colour.


Yet another tips to change MAC-address

For example, MAC-address in Gentoo can be changed in /etc/conf.d/net

mac_eth0="00:50:8D:63:41:DE"
config_eth0=( "192.168.100.37 netmask 255.255.252.0" )
routes_eth0=(
"default via 192.168.100.1"
)

Or edit /etc/network/interfaces adding one string:

pre-up ifconfig eth0 hw ether 00:00:00:00:00:00

Indeed, there are loads of variants, because it is Linux :-)

iface eth0 inet static
address 192.168.1.1
netmask 255.255.255.0
hwaddress ether xxxxxxxxxxxx

Conclusion
This post can be useful to those who connected to Internet via provider authorising by MAC-address.