macchanger - new development

Anders Sundman anders at
Mon Feb 14 20:30:44 UTC 2011


The macchanger tool is a tool originally by Alvaro Lopez Ortega used
for spoofing MAC addresses. From the Changelog, it looks like the
development stopped in 2005. The package is now listed with "Ubuntu
Developers" as it's maintainer in the repos.

I will make some changes to this program for a project I'm working on
and I would like to hear if any of those changes would be interesting
to get back into a new release of the package.

The way I see it, you can already easily change the mac by using
ifconfig, so the one thing that makes macchanger contributes to the
process is the ability to pick a "good" new address. What good means
in this context is determined by different command line switches.

Change 1:
One good option is to pick a valid mac vendor prefix (OUI) as
specified by IEEE:
The current implementation offers this functionality, but the list is
outdated and should be updated.

Change 2:
If you change your mac and then want to change back to the real,
permanent, hardware address (the one you get if you reboot your
computer) you will have to write it down and manually change it. That
sucks. I'm proposing the addition of a "-p" option that will reset the
mac to the permanent address. This is easy to do using the ethtools

Change 3:
The current "-a" option will try to change a wireless cards addr to a
mac from another wireless card, but it's implementation is less than
perfect. It tries to determine whether a card is wireless or not by
looking in a wireless.list file containing 39 vendor prefixes. If the
card is not found, a mac is picked from the full OUI database file.
Since many new wireless cards are not in the wireless list they will
likely get a mac used in cable connected NIC's.

I would like to replace this flawed behavior (perhaps keeping the
-a/-A options for backwards compatibility) by adding two new crowd
sourced lists of wireless and cable connected vendor prefixes. This
would have the added benefit that the explicit wireless / cable lists
would be listing current and (likely) common manufactures. Adding two
new option -w / -c would let the user select from these lists
explicitly - like what -A does for the complete OUI list today.

Change 4:
Today, there is a small 2^24 probability that you will get the same
mac that you are already using when you randomize the last three
bytes. I would like to fix this.

Best regards,

PS. There is also a package "macchanger-gtk" that seems broken. It
kind of works, but looks horrible and the Known vendor list is empty?
I'm not going to fix this and if no one else is, perhaps it's time to
let it die?

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