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PPPOE-RELAY(8)         DragonFly 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
       Protocol 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
              terminated.  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 approximate.
              The default value for timeout is 600 seconds (10 minutes.)

       -F     The -F option causes pppoe-relay not to fork into the
              background; 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
       concentrator.

       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
       duplicate 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
       session 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
       network 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 Dianne Skoll <dfs@roaringpenguin.com>.

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


SEE ALSO

       pppoe-start(8), pppoe-stop(8), pppoe-connect(8), pppd(8),
       pppoe.conf(5), pppoe(8), pppoe-setup(8), pppoe-status(8), pppoesniff(8)
       , pppoe-server(8)

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

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