arp(8)arp(8)NAMEarp - Displays and controls Address Resolution Protocol (ARP) tables
SYNOPSIS
/usr/sbin/arp [-u] [-n] hostname
arp [-a] [-u] [-n] [-i] system
arp [-D] hostname
arp [-d] hostname
arp [-E] hostname
arp [-f] filename
arp [-g] hostname
arp [-s] [-u] [hostname] [hardware_addr] [temp] [pub] [trail]
OPTIONS
Displays all of the current ARP entries. Disables ARP for hostname.
The hostname can be a local host name, alias, or IP address. If you use
this option, the system will no longer respond to ARP requests for this
IP address. This might cause network connectivity problems with remote
systems. Use of this option requires superuser privilege. Deletes the
entry for hostname if the user issuing the command has superuser
authority. Enables ARP for hostname. The hostname can be a local host
name, alias, or IP address. By default, the system responds to ARP
requests for all local IP addresses. You can use this option to enable
ARP for a hostname that you previously disabled with the -D option. Use
of this option requires superuser privilege. Reads entries from file‐
name and adds those entries to the ARP tables. Use of this option
requires superuser privilege. Entries in the file have the following
format: hostname hardware_addr [temp] [pub] [trail]
Fields in this format are as follows: Specifies the remote host
identified by the entry. Specifies the hardware address of the
remote host. The address format is 6 hexadecimal bytes separated
by colons; for example, xx:xx:xx:xx:xx:xx. Specifies that this
ARP table entry is temporary. When this argument is not used,
the table entry is permanent. Indicates that the table entry
will be published and that the current system will act as an ARP
server, responding to requests for hostname even though the host
address is not its own. Indicates that the trailer encapsula‐
tion may be sent to this host. Sends a gratuitous ARP packet.
The hostname can be a local host name, alias, or IP address.
Displays the interface with which the ARP entry is associated.
Displays numeric IP addresses and hardware addresses only. When
this option is not specified, arp displays hostnames, numeric IP
addresses, and hardware addresses. Creates a single ARP entry
for hostname. Use of this option requires superuser privilege.
The arguments are explained in the discussion of the -f option.
Displays the MAC address in noncanonical form with address bytes
reversed and separated by a colon character (:). By default, all
addresses are displayed in canonical form with address bytes
separated by the hyphen character (-).
When used with the -s option, this indicates that the hard‐
ware_addr is in noncanonical form.
DESCRIPTION
The arp command displays or modifies the current ARP entry for the host
specified by hostname. The host may be specified by name or number,
using Internet dot notation.
With no options, the program displays the current ARP entry for host‐
name.
The ARP tables can be displayed by any user, but only the superuser can
modify them.
EXAMPLES
To display the ARP address-mapping tables for the local host, enter:
arp-a
alpha1.dec.com (16.181.20.2) at 08-00-2b-2c-f5-31 alpha2.dec.com
(16.100.21.20) at 08-00-2b-3c-2d-fd To display the ARP address-mapping
tables for the local host and the interface, enter: arp-a -i
jupiter (192.45.20.2) at 08-00-2b-1a-f8-23 (tu0) sigma (204.126.98.16)
at 08-00-2b-5f-1d-33 (tu1) To add a single entry for the remote host
laszlo to the ARP mapping tables temporarily, enter: arp-s laszlo
08:00:2b:0f:44:23 temp
The address is considered canonical even though the bytes are
separated by colons. For input, the arp command does not use the
colon (:) and hyphen (-) characters to indicate whether the
address is canonical or noncanonical.
Note that you must have superuser authority to execute this com‐
mand. To add a single entry for the remote host laszlo to the
ARP mapping tables temporarily, enter: arp-u-s laszlo
10:00:d4:f0:22:c4 temp
The -u option indicates the address is noncanonical. Note that
you must have superuser authority to execute this command. To
add multiple entries to the ARP mapping tables from the file
newentries, enter: arp-f newentries
Note that you must have superuser authority to execute this com‐
mand.
FILES
Specifies the command path.
SEE ALSO
Commands: netstat(1), ifconfig(8)
Protocols: arp(7)
Specifications: RFC 826
arp(8)