ARP (Address Resolution Protocol) is a protocol used in local area networks (LAN).

If a computer needs to send a packet to another machine within the same local network, the IP address and MAC address (Media Access Control)  related to the network card on the receiving machine determine the allocation.

ARP provides the MAC address from the IP address of the recipient. Unfortunately often it isn’t carried out any inspection to be sure that the IP matches the destination computer which has been assigned to that MAC address. This is a vulnerability in the protocol that is often exploited by forging the IP address of a computer connected to the network and impersonating another machine / switch / hub. An attacker could impersonate the hub / switch and break the connection of a computer connected to the same network. There are several software that can exploit the weaknesses of the protocol. TuxCut has been realized for Ubuntu and it’s very similar to NetCut for Windows. TuxCut has the advantage of being able to change the MAC address. Obviously I’m not responsible of use of this software. The statements are proposed only for legitimate purposes as TuxCut can also be used by a network administrator to exclude an host from the local network.

TuxCut 3.2 is available in rpm, deb and source. Let’s see how to install it on Ubuntu. First of all download the debian package:

wget https://bitbucket.org/a_atalla/tuxcut/downloads/TuxCut-3.2_all.deb

then install it executing:

sudo dpkg -i TuxCut-3.2_all.deb

Then install the dependencies by executing:

sudo apt-get install -f

Now you can start TuxCut by clicking the icon in the system menu in the category Accessories -> TuxCut

To disconnect a machine from a local network you have just to select the ip from the list on the left and click “cut”.

If you want to change MAC address you have just to click “Change MAC address” and enter the new MAC address.

Obviously, this change requires a restart of the connection.