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PPPOE-RELAY(8)              System Manager's Manual             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 specified,
              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 fre-
              quently  than  every  30 seconds, so the timeout is approximate.
              The default value for timeout is 600 seconds (10 minutes.)


       -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 inter-
       faces 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 ses-
       sions.   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 <dfsATroaringpenguin.com>.

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


SEE ALSO
       pppd(8),        pppoe(8),        pppoe-sniff(8),        pppoe-relay(8),
       /usr/share/doc/pppoe/README.Debian.gz




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