|-a||The program displays or deletes all of the current ARP entries.|
A super-user may delete an entry for the host called
keyword is specified, only the
for this host will be deleted.
Alternatively, the -d flag may be combined with the -a flag to delete all entries.
|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|
entry for the host called
with the Ethernet address
The Ethernet address is given as six hex bytes separated by colons.
The entry will be permanent unless the word
is given in the command.
If the word
is given, the entry will be
i.e., this system will
act as an
responding to requests for
even though the host address is not its own.
In this case the
can be given as
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.|
Cause the file
to be read and multiple entries to be set in the
in the file should be of the form
hostname ether_addr [temp] [blackhole | 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.
The arp utility appeared in BSD 4.3 .