arp - manipulate the system ARP cache (net-tools, deprecated)
arp [-vn] [-i if] [-a] [hostname]Options you will use
-n- numeric addresses, no name lookups
-a- BSD-style one line per entry
-i IF- only entries on that interface
Examples
$ arp -nthe neighbour table the old way
$ ip neighthe modern replacement, with states (REACHABLE, STALE, FAILED)
Gotchas
- Not installed on Ubuntu Server; part of net-tools. ip neigh shows the same table plus the state of each entry.
Taught in
Try arp in a real terminal Free, in your browser - a real Ubuntu terminal to try it in, with missions that check your work.