arp



ARP(8)                      System Manager's Manual                     ARP(8)


NAME

     arp - address resolution display and control


SYNOPSIS

     arp [-adn] [-V rdomain] hostname
     arp [-F] [-f file] [-V rdomain] -s hostname ether_addr [temp | permanent]
         [pub]
     arp -W ether_addr [iface]


DESCRIPTION

     The arp program displays and modifies the Internet-to-Ethernet address
     translation tables used by the address resolution protocol (ARP).

     arp displays the current ARP entry for hostname when no optional
     parameters are supplied.  hostname may be specified by name or by number,
     using Internet dot notation.

     arp can also be used to send Wake on LAN (WoL) frames over a local
     Ethernet network to one or more hosts using their link layer (hardware)
     addresses.  WoL functionality is generally enabled in a machine's BIOS
     and can be used to power on machines from a remote system without having
     physical access to them.

     The options are as follows:

     -a      Display all of the current ARP entries.  See also the -d option
             below.  The following information will be printed:

                Host    The network address of the host.

                Ethernet Address
                        The Ethernet address of the host.  If the address is
                        not available, it will be displayed as
                        ``(incomplete)''.

                Netif   The network interface associated with the ARP entry.

                Expire  The time until expiry of the entry.  If the entry is
                        marked ``permanent'' or ``static'', it will never
                        expire.

                Flags   Flags on the ARP entry, in a single letter.  They are:
                        local (`l'), proxy (`P') and published (`p').

     -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      Force existing entries for the given host to be overwritten (only
             relevant to the -f and -s options).

     -f file
             Process entries from file to be set in the ARP tables.  Any
             entries in the file that already exist for a given host will not
             be overwritten unless -F is given.  Entries in the file should be
             of the form:

                   hostname ether_addr [temp | permanent] [pub]

             The entry will be static (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''; that is, 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 [temp | permanent] [pub]
             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.

             If the entry already exists for the given host, it will not be
             replaced unless -F is given.

     -V rdomain
             Select the routing domain.

     -W ether_addr [iface]
             Send the Wake on LAN frame from all interfaces on the local
             machine that are up, if iface has not been specified.  Otherwise
             the frame will be sent from iface.  ether_addr is the Ethernet
             address of the remote machine or a hostname entry in /etc/ethers.
             This option cannot be used in combination with any other option.


FILES

     /etc/ethers  Ethernet host name database.


EXAMPLES

     View the current arp(4) table, showing network addresses symbolically:

           $ arp -a

     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

     Create proxy ARP entries on interface fxp0 (MAC address
     00:90:27:bb:cc:dd), for 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


SEE ALSO

     inet_addr(3), arp(4), ethers(5), ifconfig(8), ndp(8)


HISTORY

     The arp command appeared in 4.3BSD.  Wake on LAN functionality was added
     in OpenBSD 4.9.

OpenBSD 5.9                      July 27, 2015                     OpenBSD 5.9

[Unix Hosting | Open-Source | Contact Us]
[Engineering & Automation | Software Development | Server Applications]