arp —
address resolution display and control
arp |
[ -adn
]
[-V
rdomain
]
hostname |
arp |
[ -F
]
[-f
file
]
[-V
rdomain
]
-s hostname
ether_addr [temp
| permanent
]
[pub
] |
arp |
-W
ether_addr
[iface ] |
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.
-
-
-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.
- /etc/ethers
- Ethernet host name database.
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
inet(3),
arp(4),
ethers(5),
ifconfig(8),
ndp(8)
The
arp command appeared in
4.3BSD. Wake on LAN functionality was added in
OpenBSD 4.9.
![[OpenBSD]](/openbsd.gif){kind=small}