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 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 inter-
face.
-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 speci-
fied 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 (assum-
ing 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 ses-
sion-cleaning routine runs periodically, and removes old sessions from the hash ta-
ble. A session is considered "old" if no traffic has been seen within timeout sec-
onds. 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 David F. Skoll <dfs AT 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)
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