You can delete an IP address from the arp table using the arp command along with the -d option followed by an address. For example, to delete IP 10.10.10.1:
arp -d 10.10.10.1
If you’re not sure which IP address you’re looking for then you can look at the arp table to check the IP against the MAC address by using the -a option along with arp. For example:
arp -a
To delete all of the entries in an arp table (they do regenerate after all) you can use the -d option in conjunction with the -a option:
arp -d -a
If you then want to manually add an entry into the arp table you can use the -s option followed first by the IP address and then by the MAC address, as follows (assuming an IP of 10.10.10.10 and a MAC of 00-00-00-00-00-00):
arp -s 10.10.10.10 00-00-00-00-00-00
In some cases I’ve had to revert to using hostnames instead of MAC addresses. To do so, first define the hostname in /etc/hosts, adding a line that has the IP followed by the name of the server, as follows:
havok.krypted.com 10.10.10.10
Then simply use the name instead of the MAC address with the -s option, as follows:
arp -s havok.krypted.com 10.10.10.10
