pppoe-relay

PPPOE-RELAY(8)						       PPPOE-RELAY(8)



NAME
       pppoe-relay - user-space PPPoE relay agent.

SYNOPSIS
       pppoe-relay [options]


DESCRIPTION
       pppoe-relay is a user-space relay agent for PPPoE (Point-to-Point Pro-
       tocol over Ethernet) for Linux.	pppoe-relay works in concert with the
       pppoe client and pppoe-server server.  See the OPERATION section later
       in this manual for details on how pppoe-relay works.


OPTIONS
       -S interface
	      Adds the Ethernet interface interface to the list of interfaces
	      managed by pppoe-relay.  Only PPPoE servers may be connected to
	      this interface.


       -C interface
	      Adds the Ethernet interface interface to the list of interfaces
	      managed by pppoe-relay.  Only PPPoE clients may be connected to
	      this interface.


       -B interface
	      Adds the Ethernet interface interface to the list of interfaces
	      managed  by pppoe-relay.	Both PPPoE clients and servers may be
	      connected to this interface.


       -n num Allows at most num concurrent PPPoE sessions.   If  not  speci-
	      fied, the default is 5000.  num can range from 1 to 65534.


       -i timeout
	      Specifies the session idle timeout.  If both peers in a session
	      are idle for more than timeout seconds, the session  is  termi-
	      nated.  If timeout is specified as zero, sessions will never be
	      terminated because of idleness.

	      Note that the idle-session expiry routine	 is  never  run	 more
	      frequently  than	every  30 seconds, so the timeout is approxi-
	      mate.  The default value for timeout is 600  seconds  (10	 min-
	      utes.)


       -F     The  -F  option  causes  pppoe-relay not to fork into the back-
	      ground; instead, it remains in the foreground.


       -h     The -h option prints a brief usage message and exits.


OPERATION
       pppoe-relay listens for incoming PPPoE PADI frames on  all  interfaces
       specified  with	-B  or -C options.  When a PADI frame appears, pppoe-
       relay adds a Relay-Session-ID tag  and  broadcasts  the	PADI  on  all
       interfaces  specified  with  -B or -S options (except the interface on
       which the frame arrived.)

       Any PADO frames received are relayed back to the client which sent the
       PADI  (assuming	they contain valid Relay-Session-ID tags.)  Likewise,
       PADR frames from clients are relayed back to the matching access	 con-
       centrator.

       When  a	PADS frame is received, pppoe-relay enters the two peers’ MAC
       addresses and session-ID’s into a hash table.  (The session-ID seen by
       the access concentrator may be different from that seen by the client;
       pppoe-relay must renumber sessions to avoid the possibility of  dupli-
       cate  session-ID’s.)   Whenever	either	peer  sends  a session frame,
       pppoe-relay looks up the session entry in the hash  table  and  relays
       the frame to the correct peer.

       When  a	PADT frame is received, pppoe-relay relays it to the peer and
       deletes the session entry from its hash table.

       If a client and server crash (or frames are  lost),  PADT  frames  may
       never  be  sent,	 and  pppoe-relay’s hash table can fill up with stale
       sessions.  Therefore, a session-cleaning	 routine  runs	periodically,
       and removes old sessions from the hash table.  A session is considered
       "old" if no traffic has been seen within timeout seconds.  When a ses-
       sion  is	 deleted  because  of a timeout, a PADT frame is sent to each
       peer to make certain that they are aware the session has been  killed.


EXAMPLE INVOCATIONS
       pppoe-relay -C eth0 -S eth1

       The example above relays frames between PPPoE clients on the eth0 net-
       work and PPPoE servers on the eth1 network.

       pppoe-relay -B eth0 -B eth1

       This example is a transparent relay -- frames are relayed between  any
       mix of clients and servers on the eth0 and eth1 networks.

       pppoe-relay -S eth0 -C eth1 -C eth2 -C eth3

       This  example  relays  frames  between servers on the eth0 network and
       clients on the eth1, eth2 and eth3 networks.


AUTHORS
       pppoe-relay was written by David F. Skoll <dfs@roaringpenguin.com>.

       The pppoe home page is http://www.roaringpenguin.com/pppoe/.


SEE ALSO
       adsl-start(8), adsl-stop(8), adsl-connect(8), pppd(8),  pppoe.conf(5),
       pppoe(8),   adsl-setup(8),   adsl-status(8),   pppoe-sniff(8),  pppoe-
       server(8)




4th Berkeley Distribution      26 January 2001		       PPPOE-RELAY(8)