Difference between revisions of "MAC address spoofing"

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[[Category:Networking]]
[[Category:Networking (English)]]
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[[Category:Security]]
[[Category:HOWTOs (English)]]
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[[cs:MAC Address Spoofing]]
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[[de:MAC-Adresse abfragen und setzen]]
{{i18n_entry|Česky|:MAC Address Spoofing (Česky)}}
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[[es:MAC Address Spoofing]]
{{i18n_entry|English|:MAC_Address_Spoofing}}
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[[ru:MAC Address Spoofing]]
{{i18n_entry|Русский|:Смена_MAC_адреса}}
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[[zh-CN:MAC Address Spoofing]]
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This article gives several methods to spoof a Media Access Control (MAC) address.
 +
{{Note|In the examples below is assumed the ethernet device is {{ic|eth0}}. Use {{ic|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 {{Pkg|iproute2}} (installed by default) or {{Pkg|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:
  
It is possible (for whatever reasons) to make your network card broadcast a different MAC address. Suppose your network interface is <code>ethX</code>. Then, to retrieve your MAC address:
+
{{bc|# ip link show eth0}}
$ ifconfig ethX
+
  
The thing you want is the 6 byte number in the hexadecimal form, something like this:
+
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:
HWaddr 00:1D:98:5A:D1:3A
+
  
Changing the MAC address is easy, shut down the network interface, change the MAC address and restore the interface. This can be done succinctly, as root:
+
{{bc|link/ether 00:1d:98:5a:d1:3a}}
<pre>
+
 
# /etc/rc.d/network stop
+
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:
# ifconfig ethX hw ether FF:FF:FF:FF:FF:FF
+
 
# /etc/rc.d/network start
+
{{bc|# ip link set dev eth0 down}}
</pre>
+
 
where <code>FF:FF:FF:FF:FF:FF</code> is your new MAC address.
+
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:
 +
 
 +
{{bc|# ip link set dev eth0 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:
 +
 
 +
{{bc|# ip link set dev eth0 up}}
 +
 
 +
If you want to verify that your MAC has been spoofed, simply run {{ic|ip link show eth0}} 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 {{Pkg|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.
 +
 
 +
[[Pacman|Install]] the package {{Pkg|macchanger}} from the [[Official Repositories]].
 +
 
 +
After this, the MAC can be spoofed with a random address. The syntax is {{ic|macchanger -r ''<device>''}}.
 +
 
 +
Here is an example command for spoofing the MAC address of a device named eth0.
 +
 
 +
{{bc|# macchanger -r eth0}}
 +
 
 +
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:
 +
 
 +
{{bc|# macchanger -e eth0}}
 +
 
 +
To change the MAC address to a specific value, you would run:
 +
 
 +
{{bc|1=# macchanger --mac=XX:XX:XX:XX:XX:XX eth0}}
 +
 
 +
Where {{ic|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:
 +
 
 +
{{bc|# macchanger -p eth0}}
 +
 
 +
{{Note|A device cannot be in use (connected in any way or with its interface up) while the MAC address is being changed.}}
 +
 
 +
== Automatically ==
 +
 
 +
=== netcfg ===
 +
[[Pacman|Install]] the package {{Pkg|macchanger}} from the [[Official Repositories]]. Read the [[#Method 2: macchanger]] method for more information.
 +
 
 +
Put the following line in your [[netcfg]] profile to have it spoof your MAC address when it's started:
 +
 
 +
{{bc|1=PRE_UP='macchanger -e wlan0'}}
 +
 
 +
You may have to replace {{ic|wlan0}} with your interface name.
 +
 
 +
=== Systemd Unit ===
 +
 
 +
{{hc|/etc/systemd/system/macspoof@.service|
 +
[Unit]
 +
Description&#61;MAC address change %I
 +
Before&#61;dhcpcd@%i.service
 +
 
 +
[Service]
 +
Type&#61;oneshot
 +
ExecStart&#61;/usr/sbin/ip link set dev %i address 36:aa:88:c8:75:3a
 +
ExecStart&#61;/usr/sbin/ip link set dev %i up
 +
 
 +
[Install]
 +
WantedBy&#61;network.target}}
 +
You may have to edit this file if you do not use dhcpcd.
 +
Note: This works without netcfg. If you are using netcfg, see above.
 +
 
 +
== See also ==
 +
 
 +
* [http://www.alobbs.com/macchanger macchanger project page] 
 +
* [http://www.debianadmin.com/change-your-network-card-mac-media-access-control-address.html Article on DebianAdmin] with more macchanger options.

Revision as of 11:05, 6 April 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 eth0. 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 eth0

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 eth0 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 eth0 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 eth0 up

If you want to verify that your MAC has been spoofed, simply run ip link show eth0 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 eth0.

# macchanger -r eth0

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 eth0

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

# macchanger --mac=XX:XX:XX:XX:XX:XX eth0

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 eth0
Note: A device cannot be in use (connected in any way or with its interface up) while the MAC address is being changed.

Automatically

netcfg

Install the package macchanger from the Official Repositories. Read the #Method 2: macchanger method for more information.

Put the following line in your netcfg profile to have it spoof your MAC address when it's started:

PRE_UP='macchanger -e wlan0'

You may have to replace wlan0 with your interface name.

Systemd Unit

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

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

[Install]
WantedBy=network.target

You may have to edit this file if you do not use dhcpcd. Note: This works without netcfg. If you are using netcfg, see above.

See also