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arp(8) System Manager's Manual arp(8) NAME arp - Displays and controls Address Resolution Protocol (ARP) tables SYNOPSIS /usr/sbin/arp [-u] hostname arp -a [-u] [system] arp -d hostname arp -f filename arp -s [-u] hostname hardware_addr [temp] [pub] [trail] FLAGS Displays all of the current ARP entries. Deletes the entry for host- name if the user issuing the command has superuser authority. Reads entries from filename and adds those entries to the ARP tables. Use of this flag 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 is given as 6 hexadecimal bytes sepa- rated by colons. Specifies that this ARP table entry is tempo- rary. When this argument is not used, the table entry is perma- nent. Indicates that the table entry will be published and that the current system will act as an ARP server, responding to re- quests for hostname even though the host address is not its own. Indicates that the trailer encapsulation may be sent to this host. Creates a single ARP entry for hostname. Use of this flag requires superuser privilege. The arguments are explained in the discussion of the -f flag. 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 char- acter (-). When used with the -s flag, 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 flags, 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 To display the ARP address-mapping tables for the local host that has one interface defined, 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 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 ad- dress 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 flag 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 newen- tries, enter: arp -f newentries Note that you must have superuser authority to execute this com- mand. FILES Specifies the command path. RELATED INFORMATION Commands: netstat(1), ifconfig(8) Protocols: arp(7) Specifications: RFC826 delim off arp(8)