NAME    [Toc]    [Back]

     arp - address resolution display and control

SYNOPSIS    [Toc]    [Back]

     arp [-n] hostname
     arp [-n] -a
     arp -d hostname
     arp -d -a
     arp -s hostname ether_addr [temp | permanent] [pub]
     arp -f filename

DESCRIPTION    [Toc]    [Back]

     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.


     Available options:

     -a      Display all of the current ARP  entries.   See  also
the -d option
             below.

     -d       Delete  an entry for the host called hostname.  Alternatively, the
             -d flag may be combined with the -a flag  to  delete
all entries,
             with  hostname lookups automatically disabled.  Only
the superuser
             may delete entries.

     -f filename
             Process entries from filename to be set in  the  ARP
tables.  Entries
 in the file should be of the form:

                   hostname ether_addr [temp | permanent] [pub]

             The  entry  will be static, i.e., will not time out,
unless the
             word temp is given in the command.  A static ARP entry can be
             overwritten  by  network  traffic,  unless  the word
permanent is given.
  If the word pub is 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.
             This  behavior  has  traditionally been called proxy
ARP.

     -n      Show network addresses as numbers (normally arp  attempts to display
 addresses symbolically).

     -s hostname ether_addr
             Create  an  ARP  entry  for the host called hostname
with the Ethernet
 address ether_addr.   The  Ethernet  address  is
given as six
             hexadecimal bytes separated by colons.

             The  permanent, pub, or temp modifiers may be specified with meanings
 as given above.

EXAMPLES    [Toc]    [Back]

     To view the current arp(4) table:

           $ arp -a

     To create a permanent entry (one that cannot be  overwritten
by other network
 traffic):

           # arp -s 10.0.0.2 00:90:27:bb:cc:dd permanent

     To  create  proxy ARP entries on an interface, fxp0, for the
IP addresses
     204.1.2.3 and 204.1.2.4:

           # arp -s 204.1.2.3 00:90:27:bb:cc:dd pub
           # arp -s 204.1.2.4 00:90:27:bb:cc:dd pub

     (where 00:90:27:bb:cc:dd is the MAC address of fxp0)

SEE ALSO    [Toc]    [Back]

     inet(3), arp(4), ifconfig(8)

HISTORY    [Toc]    [Back]

     The arp command appeared in 4.3BSD.

OpenBSD     3.6                           July      14,      1999