Redhat: Network Diagnostics

Arp

Address Resolution Protocol associates IP addresses with MAC addresses. Running ARM will display the a list of recent connections, showing the IP address, hostname and MAC address.

[root@head ~]# arp
Address                  HWtype  HWaddress           Flags Mask            Iface
compute000-ipmi.compute  ether   00:25:90:58:5c:bf   C                     eth0
compute002.compute.bost  ether   00:25:90:58:5c:56   C                     eth0
pxe                      ether   52:54:00:e7:3e:7d   C                     br0
172.28.12.3              ether   fc:2f:40:c8:7c:08   C                     br0

Remove an ARP entry

arp -d <hostname>

Add an ARP entry

arp -s <hostname> <MAC address>