ARP spoofing is a type of attack in which an attacker sends fake ARP (Address Resolution Protocol) messages to a network, in order to associate their own MAC (Media Access Control) address with the IP address of another device on the network. This can allow the attacker to intercept communication between devices on the network, or to perform other malicious activities.
To detect ARP spoofing on a UNIX or Linux system, you can use the arpwatch utility. arpwatch is a tool that monitors ARP traffic on a network and sends an email notification when it detects a new MAC address on the network or a change in the MAC address of an existing device.
To install arpwatch on a UNIX or Linux system, you will first need to install the arpwatch package. On most systems, you can install the package using the package manager:
apt-get install arpwatch
Once arpwatch is installed, you can start the arpwatch daemon by running the following command:
/etc/init.d/arpwatch start
arpwatch will then start monitoring ARP traffic on the network and sending email notifications when it detects any changes.
You can also use the tcpdump utility to manually monitor ARP traffic on the network and look for suspicious activity. To do this, you can run the following command:
tcpdump -n -i eth0 arp
This will capture and display all ARP traffic on the network interface eth0. You can then examine the output to look for any suspicious ARP messages.