ARP linux command manual

ARP(8)                        Linux Programmer's Manual                    ARP(8)

       arp - manipulate the system ARP cache

       arp [-evn] [-H type] [-i if] -a [hostname]

       arp [-v] [-i if] -d hostname [pub]

       arp [-v] [-H type] [-i if] -s hostname hw_addr [temp]

       arp [-v] [-H type] [-i if] -s hostname hw_addr [netmask nm] pub

       arp [-v] [-H type] [-i if] -Ds hostname ifa [netmask nm] pub

       arp [-vnD] [-H type] [-i if] -f [filename]

       Arp  manipulates  the kernel's ARP cache in various ways.  The primary
       options are clearing an address mapping entry and manually setting  up
       one.   For  debugging purposes, the arp program also allows a complete
       dump of the ARP cache.

       -v, --verbose
              Tell the user what is going on by being verbose.

       -n, --numeric
              shows numerical addresses instead of trying to  determine  sym-
              bolic host, port or user names.

       -H type, --hw-type type, -t type
              When  setting or reading the ARP cache, this optional parameter
              tells arp which class of entries  it  should  check  for.   The
              default  value  of  this parameter is ether (i.e. hardware code
              0x01 for IEEE  802.3  10Mbps  Ethernet).   Other  values  might
              include  network  technologies such as ARCnet (arcnet) , PROnet
              (pronet) , AX.25 (ax25) and NET/ROM (netrom).

       -a [hostname], --display [hostname]
              Shows the entries of the  specified  hosts.   If  the  hostname
              parameter  is  not  used,  all  entries will be displayed.  The
              entries will be displayed in alternate (BSD) style.

       -d hostname, --delete hostname
              Remove any entry for the specified host.  This can be  used  if
              the indicated host is brought down, for example.

       -D, --use-device
              Use the interface ifa's hardware address.

       -e     Shows the entries in default (Linux) style.

       -i If, --device If
              Select  an  interface.  When dumping the ARP cache only entries
              matching the specified interface will be printed. When  setting
              a permanent or temp ARP entry this interface will be associated
              with the entry; if this option is not  used,  the  kernel  will
              guess based on the routing table. For pub entries the specified
              interface is the  interface  on  which  ARP  requests  will  be
              NOTE:  This has to be different from the interface to which the
              IP datagrams will be routed.

       -s hostname hw_addr, --set hostname
              Manually create an ARP address mapping entry for host  hostname
              with  hardware  address  set  to  hw_addr  class,  but for most
              classes one can assume that the usual presentation can be used.
              For  the  Ethernet class, this is 6 bytes in hexadecimal, sepa-
              rated by colons. When adding proxy arp entries (that  is  those
              with  the  publish flag set a netmask may be specified to proxy
              arp for entire subnets. This is not good practice, but is  sup-
              ported  by  older kernels because it can be useful. If the temp
              flag is not supplied entries will be permanent stored into  the
              ARP cache.
              NOTE: As of kernel 2.2.0 it is no longer possible to set an ARP
              entry for an entire subnet. Linux instead does automagic  proxy
              arp  when  a  route exists and it is forwarding. See arp(7) for

       -f filename, --file filename
              Similar to the -s option, only this time the  address  info  is
              taken  from file filename set up.  The name of the data file is
              very often /etc/ethers, but this is not official. If  no  file-
              name is specified /etc/ethers is used as default.

              The  format  of the file is simple; it only contains ASCII text
              lines with a hostname, and  a  hardware  address  separated  by
              whitespace. Additionally the pub, temp and netmask flags can be

       In all places where a hostname is expected, one can also enter  an  IP
       address in dotted-decimal notation.

       As  a special case for compatibility the order of the hostname and the
       hardware address can be exchanged.

       Each complete entry in the ARP cache will be marked with the  C  flag.
       Permanent  entries  are marked with M and published entries have the P


       rarp(8), route(8), ifconfig(8), netstat(8)

       Fred  N.  van  Kempen,    with  a  lot  of
       improvements   from   net-tools   Maintainer   Bernd  Eckenfels  .

net-tools                         5 Jan 1999                           ARP(8)