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arp(8)
NAME
  arp - 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
  -a  Displays all of the current ARP entries.

  -D hostname
      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.

  -d hostname
      Deletes the entry for hostname if the user issuing the command has
      superuser authority.

  -E hostname
      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.

  -f filename
      Reads entries from filename 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:

  hostname
      Specifies the remote host identified by the entry.

  hardware_addr
      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.

  temp
      Specifies that this ARP table entry is temporary. When this argument is
      not used, the table entry is permanent.

  pub 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.

  trail
      Indicates that the trailer encapsulation may be sent to this host.

  -g hostname
      Sends a gratuitous ARP packet.  The hostname can be a local host name,
      alias, or IP address.

  -i  Displays the interface with which the ARP entry is associated.

  -n  Displays numeric IP addresses and hardware addresses only.  When this
      option is not specified, arp displays hostnames, numeric IP addresses,
      and hardware addresses.

  -s hostname hardware_addr [temp] [pub] [trail]
      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.

  [-u]
      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 hardware_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 hostname.

  The ARP tables can be displayed by any user, but only the superuser can
  modify them.

EXAMPLES
   1.  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

   2.  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)

   3.  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 command.

   4.  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.

   5.  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 command.

FILES
  /usr/sbin/arp
      Specifies the command path.

SEE ALSO
  Commands: netstat(1), ifconfig(8)

  Protocols: arp(7)

  Specifications:  RFC 826

Index for Section 8

Alphabetical listing for A

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