The arp table or arp cache keeps track of all devices on your network that your computer is capable of communicating with. It stores the Layer 2 data ( MAC addresses ) as well as the interface in which the device is connected through (i.e. which interface the traffic came in on ). This table can be viewed, modified, flushed using the arp command in Linux
View Arp Cache Entries
The output will something like the following.
Address HWtype HWaddress Flags Mask Iface
192.168.1.100 ether 00:21:a0:63:38:3f C eth0
Add Static Arp Entry
To add an arp entry we simply take advantage of the options that the arp command provides. Lets add an arbitrary entry.
arp -i eth0 -s 10.11.12.13 de:ad:be:ef:fe:ed
Remove Entry From Arp Cache
To remove an entry we can refer to the initial help output I pasted above.
arp -i <if>] -d <host>
Some example usages are given below
arp -i eth0 -d 10.11.12.13
arp -d 192.168.1.100
Clearing arp cache with verbose
ip -s -s neigh flush all