NAME

       arptables - ARP table administration

SYNOPSIS

       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]

DESCRIPTION

       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.

   CHAINS
       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 rule.

   TARGETS
       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.

   TABLES
       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 used.

       -t, --table
              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 kernels.

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.

   COMMANDS
       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.

       -A, --append
              Append a rule to the end of the selected chain.

       -D, --delete
              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.

       -I, --insert
              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.

       -R, --replace
              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.

       -P, --policy
              Set the policy for the chain to the given target. The policy can be ACCEPT, DROP or
              RETURN.

       -F, --flush
              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.

       -Z, --zero
              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.

       -L, --list
              List all rules in the selected chain. If no  chain  is  selected,  all  chains  are
              listed.

       -N, --new-chain
              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.

       -X, --delete-chain
              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.

       -E, --rename-chain
              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.

   MISCELLANOUS COMMANDS
       -V, --version
              Show the version of the arptables userspace program.

       -h, --help
              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.

   RULE-SPECIFICATIONS
       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 this option.

       -l, --h-length length[/mask]
              The hardware length (nr of bytes)

       --opcode code[/mask]
              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.

       --h-type type[/mask]
              The hardware type (2 bytes, hexadecimal). Available values are: 1=Ethernet.

       --proto-type type[/mask]
              The protocol type (2 bytes). Available values are: 0x800=IPv4.

   TARGET-EXTENSIONS
       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
       --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.

       --mangle-target target
              Target of ARP mangle operation (DROP, CONTINUE or ACCEPT -- default is ACCEPT).

MAILINGLISTS

       ebtables-user@lists.sourceforge.net
       ebtables-devel@lists.sourceforge.net

SEE ALSO

       iptables(8), ebtables(8), arp(8), rarp(8), ifconfig(8), route(8)

                                           August 2007                               ARPTABLES(8)