arp —
address resolution display and control
  
    | arp | [ -v]-dhostname [proxy] | 
  
    | arp | -shostname ether_addr
      [temp] [pub[proxy]] | 
The arp program displays and modifies the
  Internet-to-Ethernet address translation tables used by the address resolution
  protocol (arp(4)). With no flags,
  the program displays the current ARP entry for hostname.
  The host may be specified by name or by number, using Internet dot notation.
The state of the arp entry is shown as a single letter preceded by
    the time the state is applicable for:
  - D
- Delay
- I
- Incomplete
- N
- Nostate
- P
- Probe
- R
- Reachable
- S
- Stale
- U
- Unreachable
- W
- Waitdelete
- ?
- Unknown state (should never happen).
Available options:
  - -a
- The program displays all of the current ARP entries.
- -d
- A super-user may delete an entry for the host called
      hostname with the -dflag.
      If theproxykeyword is specified, only the
      published “proxy only” ARP entry for this host will be
      deleted. If used with-ainstead of a
      hostname, it will delete all arp entries.
- -f
- Causes the file filename to be read and multiple
      entries to be set in the ARP tables. Entries in the file should be of the
      form
    
    hostname ether_addr
      [temp] [pub]
 with argument meanings as described below. 
- -n
- Show network addresses as numbers (normally arpattempts to display addresses symbolically).
- -shostname ether_addr
- Create an ARP entry for the host called hostname
      with the Ethernet address ether_addr. The Ethernet
      address is given as six hex bytes separated by colons. The entry will be
      permanent unless the word tempis given in the
      command. If the wordpubis given, the entry will
      be "published"; i.e., this system will act as an ARP server,
      responding to requests for hostname even though the
      host address is not its own.If the word proxyis also given, the
        published entry will be a “proxy only” entry. In this case
        the ether_addr can be given asautoin which case the interfaces on this host
        will be examined, and if one of them is found to occupy the same subnet,
        its Ethernet address will be used.
 
- -v
- Display verbose information when adding or deleting ARP entries.
Thearp command appeared in
  4.3BSD.