The
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:
-a
The program displays or 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
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
only
keyword is also specified, this will create a
``published (proxy only)''
entry.
This type of entry is created automatically if
detects that a routing table entry for
hostname
already exists.
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
]
[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.
