Difference between revisions of "MAC address spoofing"

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== Automatically ==
 
== Automatically ==
 
=== Netcfg ===
 
 
{{Out of date|netcfg is deprecated, use [[netctl]] instead}}
 
 
This example uses [[#Method 2: macchanger]], so make sure that {{Pkg|macchanger}} is [[Pacman|installed]].
 
 
Put the following line in your [[netcfg]] profile to have it spoof your MAC address when it's started:
 
 
PRE_UP='macchanger -e enp1s0'
 
 
You may have to replace {{ic|enp1s0}} with your interface name.
 
  
 
=== Systemd unit ===
 
=== Systemd unit ===

Revision as of 11:41, 21 October 2013

This article gives several methods to spoof a Media Access Control (MAC) address.

Note: In the examples below is assumed the ethernet device is enp1s0. Use ip link to check your actual device name, and adjust the examples as necessary

Manually

There are two methods for spoofing a MAC address using either iproute2 (installed by default) or macchanger (available on the official repositories).

Both of them are outlined below.

Method 1: iproute2

First, you can check your current MAC address with the command:

# ip link show enp1s0

The section that interests us at the moment is the one that has "link/ether" followed by a 6-byte number. It will probably look something like this:

link/ether 00:1d:98:5a:d1:3a

The first step to spoofing the MAC address is to bring the network interface down. You must be logged in as root to do this. It can be accomplished with the command:

# ip link set dev enp1s0 down

Next, we actually spoof our MAC. Any hexadecimal value will do, but some networks may be configured to refuse to assign IP addresses to a client whose MAC does not match up with a vendor. Therefore, unless you control the network(s) you are connecting to, it is a good idea to test this out with a known good MAC rather than randomizing it right away.

To change the MAC, we need to run the command:

# ip link set dev enp1s0 address XX:XX:XX:XX:XX:XX

Where any 6-byte value will suffice for 'XX:XX:XX:XX:XX:XX'.

The final step is to bring the network interface back up. This can be accomplished by running the command:

# ip link set dev enp1s0 up

If you want to verify that your MAC has been spoofed, simply run ip link show enp1s0 again and check the value for 'link/ether'. If it worked, 'link/ether' should be whatever address you decided to change it to.

Method 2: macchanger

Another method uses macchanger (a.k.a., the GNU MAC Changer). It provides a variety of features such as changing the address to match a certain vendor or completely randomizing it.

Install the package macchanger from the official repositories.

After this, the MAC can be spoofed with a random address. The syntax is macchanger -r <device>.

Here is an example command for spoofing the MAC address of a device named enp1s0.

# macchanger -r enp1s0

To randomize all of the address except for the vendor bytes (that is, so that if the MAC address was checked it would still register as being from the same vendor), you would run the command:

# macchanger -e enp1s0

To change the MAC address to a specific value, you would run:

# macchanger --mac=XX:XX:XX:XX:XX:XX enp1s0

Where XX:XX:XX:XX:XX:XX is the MAC you wish to change to.

Finally, to return the MAC address to its original, permanent hardware value:

# macchanger -p enp1s0
Note: A device cannot be in use (connected in any way or with its interface up) while the MAC address is being changed.

Automatically

Systemd unit

This example uses #Method 1: iproute2.

/etc/systemd/system/macspoof@.service
[Unit]
Description=MAC address change %I
Before=dhcpcd@%i.service

[Service]
Type=oneshot
ExecStart=/usr/bin/ip link set dev %i address 36:aa:88:c8:75:3a
ExecStart=/usr/bin/ip link set dev %i up

[Install]
WantedBy=network.target

You may have to edit this file if you do not use dhcpcd.

Systemd unit using random address

This example uses #Method 2: macchanger, so make sure that macchanger is installed.

/etc/systemd/system/macchanger@.service
[Unit]
Description=Macchanger service for %I
Documentation=man:macchanger(1)

[Service]
ExecStart=/usr/bin/macchanger -e %I
Type=oneshot

[Install]
WantedBy=multi-user.target

See also