Article Date:10th January 2002 Author(s): Clinton "SileNceR" Warburton, Jarrod "sKuLLsHoT" Mast Our Rating: 9/10

*NIX

How to do it all on *nix

To set ones MAC address under *NIX (from Linux to FreeBSD to Unix on a Sun U-SPARC machine) the syntax SHOULD¹ be as follows:

/sbin/ifconfig eth0 down

where eth0 is the ethernet device; ifconfig without /sbin/ should also work and would be preferred on the afore mentioned Sun machine where the ifconfig location is /usr/sbin/ifconfig

/sbin/ifconfig eth0 hw ether 00:00:00:00:00:00

where /sbin/ifconfig and eth0 are as before, and 00:00:00:00:00:00 represents the MAC address you would like to take and call your own. From this point, you should be able to use the connection again, if not try

/sbin/ifconfig eth0 up

If this presents errors I suggest you set the MAC address back to the original one (you did write it down, didn't you :Þ).

This method has been tested in all of RedHat 6.2 and 7.1 (linux) and FreeBSD 4.3 (BSD), however not all linux, BSD and Unix distros definately work, you may need to use another command to change this, however if you are running a sun box you should already know it or how to find it :) google is your friend.

So, as always - proceed with care, changing it to a non-working MAC may stop your machine dead in its tracks, however for the MAC change to be permanant it has to be set on startup (ifconfig must use the real MAC by default on startup) just add the "ifconfig eth0 hw ether" etc to your rc.d or similar file.

¹ - SHOULD implies we are right, which as often as not may well be the opposite of the truth.

My BSD box failed to renew its new IP from the DHCP server and hence lost all networking until reboot - hence the following warning - DO NOT try this on mission critical networked machines, especially not servers.