NAME

       parprouted - Proxy ARP IP bridging daemon

SYNOPSIS

       parprouted [-d] [-p] interface [interface]

DESCRIPTION

       parprouted  is a daemon for transparent IP (Layer 3) proxy ARP bridging.  Unlike standard bridging, proxy
       ARP bridging allows to bridge Ethernet networks behind wireless nodes. Normal L2 bridging does  not  work
       between  wireless  nodes  because  wireless  does not know about MAC addresses used in the wired Ethernet
       networks. Also this daemon is useful for making transparent firewalls.

       The daemon listens for incoming ARP requests, and in case the location of the  requested  IP  address  is
       unknown,  forwards  them  to  other  interfaces,  as  well  as updates kernel ARP table with the received
       replies. When necessary, the daemon generates an ARP reply itself, which  causes  the  stations  to  send
       traffic  to the host daemon is running on. By automatically adding appropriate /32 routes to Linux kernel
       IP routing table for the hosts learned via ARP, daemon ensures that the Linux  kernel  will  be  able  to
       route  the  packets  to  the  destination  host when it receives them without any need routing/subnetting
       manually.

       All routes entered by the daemon have a metric of 50.

       Unless you use -p switch, all entries in the ARP table  will  be  refreshed  (rechecked  by  sending  ARP
       requests) every 50 seconds. This keeps them from being expired by kernel.

       Normally  it  takes  about  60  ms for a bridge to update all its tables and start sending packets to the
       destination.

REQUIREMENTS

       This daemon can be used for unicast traffic only. I.e., DHCP is not  supported.   Use  software  such  as
       dhcrelay to "bridge" DHCP.

       You  should  have  an  IP address assigned on all of your interfaces that you do bridging on. There is no
       need for this address to be from the same networks as the bridged networks. Any dummy address will do.

       The system should have correct default route.

       parprouted requires "ip" program from iproute2 tools to be installed in /sbin.  If  it  is  installed  in
       another  location,  please replace "/sbin/ip" occurances in the source with the correct path. As well you
       should have proc filesystem mounted in /proc because the daemon uses /proc/net/arp.

       parprouted is designed for and tested only with Linux 2.4.x kernels.

OPTIONS

       The list of interfaces to do bridging on should be given via the command line.

       The daemon accepts the following switches:

       -d, which stands for debugging. If you run it in debugging mode the daemon will not go to background  and
       will print additional debugging information to stdout/stderr.

       -p,  which  makes  all  ARP entries to be permanent. This will also result in that ARP tables will not be
       refreshed by ARP pings.

EXAMPLE

       To bridge between wlan0 and eth0: parprouted eth0 wlan0

AUTHOR

        (C) 2004, Vladimir Ivaschenko <vi@maks.net>
        http://www.hazard.maks.net

parprouted                                        January 2004                                     PARPROUTED(8)