arptables - ARP table administration
arptables [-t table] -[AD] chain rule-specification [options]
arptables [-t table] -[RI] chain rulenum rule-specification [options]
arptables [-t table] -D chain rulenum [options]
arptables [-t table] -[LFZ] [chain] [options]
arptables [-t table] -[NX] chain
arptables [-t table] -E old-chain-name new-chain-name
arptables [-t table] -P chain target [options]
arptables is a user space tool, it is used to set up and maintain the
tables of ARP rules in the Linux kernel. These rules inspect the ARP
frames which they see. arptables is analogous to the iptables user
space tool, but arptables is less complicated.
The kernel table is used to divide functionality into different sets of
rules. Each set of rules is called a chain. Each chain is an ordered
list of rules that can match ARP frames. If a rule matches an ARP
frame, then a processing specification tells what to do with that
matching frame. The processing specification is called a ’target’.
However, if the frame does not match the current rule in the chain,
then the next rule in the chain is examined and so forth. The user can
create new (user-defined) chains which can be used as the ’target’ of a
A firewall rule specifies criteria for an ARP frame and a frame
processing specification called a target. When a frame matches a rule,
then the next action performed by the kernel is specified by the
target. The target can be one of these values: ACCEPT, DROP, CONTINUE,
RETURN, an ’extension’ (see below) or a user-defined chain.
ACCEPT means to let the frame through. DROP means the frame has to be
dropped. CONTINUE means the next rule has to be checked. This can be
handy to know how many frames pass a certain point in the chain or to
log those frames. RETURN means stop traversing this chain and resume
at the next rule in the previous (calling) chain. For the extension
targets please see the TARGET EXTENSIONS section of this man page.
There is only one ARP table in the Linux kernel. The table is filter.
You can drop the ’-t filter’ argument to the arptables command. The -t
argument must be the first argument on the arptables command line, if
filter, is the only table and contains two (Linux kernels 2.4.X)
or three (Linux kernels 2.6.0 and later) built-in chains: INPUT
(for frames destined for the host), OUTPUT (for locally-
generated frames) and FORWARD (for frames being forwarded by the
bridge code). The FORWARD chain doesn’t exist in Linux 2.4.X
ARPTABLES COMMAND LINE ARGUMENTS
After the initial arptables command line argument, the remaining
arguments can be divided into several different groups. These groups
are commands, miscellaneous commands, rule-specifications, match-
extensions, and watcher-extensions.
The arptables command arguments specify the actions to perform on the
table defined with the -t argument. If you do not use the -t argument
to name a table, the commands apply to the default filter table. With
the exception of the -Z command, only one command may be used on the
command line at a time.
Append a rule to the end of the selected chain.
Delete the specified rule from the selected chain. There are two
ways to use this command. The first is by specifying an interval
of rule numbers to delete, syntax: start_nr[:end_nr]. Using
negative numbers is allowed, for more details about using
negative numbers, see the -I command. The second usage is by
specifying the complete rule as it would have been specified
when it was added.
Insert the specified rule into the selected chain at the
specified rule number. If the current number of rules equals N,
then the specified number can be between -N and N+1. For a
positive number i, it holds that i and i-N-1 specify the same
place in the chain where the rule should be inserted. The number
0 specifies the place past the last rule in the chain and using
this number is therefore equivalent with using the -A command.
Replaces the specified rule into the selected chain at the
specified rule number. If the current number of rules equals N,
then the specified number can be between 1 and N. i specifies
the place in the chain where the rule should be replaced.
Set the policy for the chain to the given target. The policy can
be ACCEPT, DROP or RETURN.
Flush the selected chain. If no chain is selected, then every
chain will be flushed. Flushing the chain does not change the
policy of the chain, however.
Set the counters of the selected chain to zero. If no chain is
selected, all the counters are set to zero. The -Z command can
be used in conjunction with the -L command. When both the -Z
and -L commands are used together in this way, the rule counters
are printed on the screen before they are set to zero.
List all rules in the selected chain. If no chain is selected,
all chains are listed.
Create a new user-defined chain with the given name. The number
of user-defined chains is unlimited. A user-defined chain name
has maximum length of 31 characters.
Delete the specified user-defined chain. There must be no
remaining references to the specified chain, otherwise arptables
will refuse to delete it. If no chain is specified, all user-
defined chains that aren’t referenced will be removed.
Rename the specified chain to a new name. Besides renaming a
user-defined chain, you may rename a standard chain name to a
name that suits your taste. For example, if you like PREBRIDGING
more than PREROUTING, then you can use the -E command to rename
the PREROUTING chain. If you do rename one of the standard
arptables chain names, please be sure to mention this fact
should you post a question on the arptables mailing lists. It
would be wise to use the standard name in your post. Renaming a
standard arptables chain in this fashion has no effect on the
structure or function of the arptables kernel table.
Show the version of the arptables userspace program.
Give a brief description of the command syntax.
-j, --jump target
The target of the rule. This is one of the following values:
ACCEPT, DROP, CONTINUE, RETURN, a target extension (see TARGET
EXTENSIONS) or a user-defined chain name.
The following command line arguments make up a rule specification (as
used in the add and delete commands). A "!" option before the
specification inverts the test for that specification. Apart from these
standard rule specifications there are some other command line
arguments of interest.
-s, --source-ip [!] address[/mask]
The Source IP specification.
-d, --destination-ip [!] address[/mask]
The Destination IP specification.
--source-mac [!] address[/mask]
The source mac address. Both mask and address are written as 6
hexadecimal numbers separated by colons.
--destination-mac [!] address[/mask]
The destination mac address. Both mask and address are written
as 6 hexadecimal numbers separated by colons.
-i, --in-interface [!] name
The interface via which a frame is received (for the INPUT and
FORWARD chains). The flag --in-if is an alias for this option.
-o, --out-interface [!] name
The interface via which a frame is going to be sent (for the
OUTPUT and FORWARD chains). The flag --out-if is an alias for
-l, --h-length length[/mask]
The hardware length (nr of bytes)
The operation code (2 bytes). Available values are: 1=Request
2=Reply 3=Request_Reverse 4=Reply_Reverse 5=DRARP_Request
6=DRARP_Reply 7=DRARP_Error 8=InARP_Request 9=ARP_NAK.
The hardware type (2 bytes, hexadecimal). Available values are:
The protocol type (2 bytes). Available values are: 0x800=IPv4.
arptables extensions are precompiled into the userspace tool. So there
is no need to explicitly load them with a -m option like in iptables.
However, these extensions deal with functionality supported by
supplemental kernel modules.
--mangle-ip-s IP address
Mangles Source IP Address to given value.
--mangle-ip-d IP address
Mangles Destination IP Address to given value.
--mangle-mac-s MAC address
Mangles Source MAC Address to given value.
--mangle-mac-d MAC address
Mangles Destination MAC Address to given value.
Target of ARP mangle operation (DROP, CONTINUE or ACCEPT --
default is ACCEPT).
iptables(8), ebtables(8), arp(8), rarp(8), ifconfig(8), route(8)