arp(8) manual page

The arp utility 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:

--libxo

Generate output via libxo(3) in a selection of different human and machine readable formats. See xo_parse_args(3) for details on command line arguments.

-a

The program displays or, if it is used with the -d flag, deletes all of the current ARP entries.

-d

A super-user may delete an entry for the host called hostname with the -d flag. If the pub keyword is specified, only the "published" ARP entry for this host will be deleted.
Alternatively, the -d flag may be combined with the -a flag to delete all entries.

-i interface

Limit the operation scope to the ARP entries on interface. Applicable only to the following operations: display one, display all, delete all.

-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 hex bytes separated by colons. The entry will be permanent unless the word temp is given in the command. 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. In this case the ether_addr can be given as auto in 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.
If the reject keyword is specified the entry will be marked so that traffic to the host will be discarded and the sender will be notified the host is unreachable. The blackhole keyword is similar in that traffic is discarded but the sender is not notified. These can be used to block external traffic to a host without using a firewall.

-S hostname ether_addr

Is just like -s except any existing ARP entry for this host will be deleted first.

-f filename

Cause 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] [ blackhole amp;| reject] [ pub]
with argument meanings as given above. Leading whitespace and empty lines are ignored. A ‘#’ character will mark the rest of the line as a comment.

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Manual Pages — ARP

NAME

CONTENTS

SYNOPSIS

DESCRIPTION

SEE ALSO

HISTORY

--libxo
	Generate output via libxo(3) in a selection of different human and machine readable formats. See xo_parse_args(3) for details on command line arguments.
-a
	The program displays or, if it is used with the -d flag, deletes all of the current ARP entries.
-d
	A super-user may delete an entry for the host called hostname with the -d flag. If the pub keyword is specified, only the "published" ARP entry for this host will be deleted. Alternatively, the -d flag may be combined with the -a flag to delete all entries.
-i interface
	Limit the operation scope to the ARP entries on interface. Applicable only to the following operations: display one, display all, delete all.
-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 hex bytes separated by colons. The entry will be permanent unless the word temp is given in the command. 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. In this case the ether_addr can be given as auto in 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. If the reject keyword is specified the entry will be marked so that traffic to the host will be discarded and the sender will be notified the host is unreachable. The blackhole keyword is similar in that traffic is discarded but the sender is not notified. These can be used to block external traffic to a host without using a firewall.
-S hostname ether_addr
	Is just like -s except any existing ARP entry for this host will be deleted first.
-f filename
	Cause 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] [ blackhole amp;\| reject] [ pub] with argument meanings as given above. Leading whitespace and empty lines are ignored. A ‘`#`’ character will mark the rest of the line as a comment.