.\" $Id: pppoe-relay.8,v 1.7 2005/08/09 02:29:58 dfs Exp $ .\" LIC: GPL.TH PPPOE-RELAY 8 "26 January 2001".\"".UC 4.SH NAMEpppoe-relay \- user-space PPPoE relay agent..SH SYNOPSIS.B pppoe-relay \fR[\fIoptions\fR].SH DESCRIPTION\fBpppoe-relay\fR is a user-space relay agent for PPPoE(Point-to-Point Protocol over Ethernet) for Linux.  \fBpppoe-relay\fRworks in concert with the \fBpppoe\fR client and \fBpppoe-server\fRserver.  See the OPERATION section later in this manual fordetails on how \fBpppoe-relay\fR works..SH OPTIONS.TP.B \-S \fIinterface\fRAdds the Ethernet interface \fIinterface\fR to the list of interfacesmanaged by \fBpppoe-relay\fR.  Only PPPoE servers may be connected tothis interface..TP.B \-C \fIinterface\fRAdds the Ethernet interface \fIinterface\fR to the list of interfacesmanaged by \fBpppoe-relay\fR.  Only PPPoE clients may be connected tothis interface..TP.B \-B \fIinterface\fRAdds the Ethernet interface \fIinterface\fR to the list of interfacesmanaged by \fBpppoe-relay\fR.  Both PPPoE clients and servers may beconnected to this interface..TP.B \-n \fInum\fRAllows at most \fInum\fR concurrent PPPoE sessions.  If not specified,the default is 5000.  \fInum\fR can range from 1 to 65534..TP.B \-i \fItimeout\fRSpecifies the session idle timeout.  If both peers in a session are idlefor more than \fItimeout\fR seconds, the session is terminated.If \fItimeout\fR is specified as zero, sessions will never be terminatedbecause of idleness.Note that the idle-session expiry routine is never run more frequently thanevery 30 seconds, so the timeout is approximate.  The default value for\fItimeout\fR is 600 seconds (10 minutes.).TP.B \-FThe \fB\-F\fR option causes \fBpppoe-relay\fR \fInot\fR to fork into thebackground; instead, it remains in the foreground..TP.B \-hThe \fB\-h\fR option prints a brief usage message and exits..SH OPERATION\fBpppoe-relay\fR listens for incoming PPPoE PADI frames on all interfacesspecified with \fB-B\fR or \fB-C\fR options.  When a PADI frame appears,\fBpppoe-relay\fR adds a Relay-Session-ID tag and broadcasts the PADIon all interfaces specified with \fB-B\fR or \fB-S\fR options (except theinterface on which the frame arrived.)Any PADO frames received are relayed back to the client which sent thePADI (assuming they contain valid Relay-Session-ID tags.)  Likewise,PADR frames from clients are relayed back to the matching accessconcentrator.When a PADS frame is received, \fBpppoe-relay\fR enters the two peers'MAC addresses and session-ID's into a hash table.  (The session-ID seenby the access concentrator may be different from that seen by the client;\fBpppoe-relay\fR must renumber sessions to avoid the possibility of duplicatesession-ID's.)  Whenever either peer sends a session frame, \fBpppoe-relay\fRlooks up the session entry in the hash table and relays the frame tothe correct peer.When a PADT frame is received, \fBpppoe-relay\fR relays it to the peerand deletes the session entry from its hash table.If a client and server crash (or frames are lost), PADT frames may neverbe sent, and \fBpppoe-relay\fR's hash table can fill up with stale sessions.Therefore, a session-cleaning routine runs periodically, and removes oldsessions from the hash table.  A session is considered "old" if no traffichas been seen within \fItimeout\fR seconds.  When a session is deleted becauseof a timeout, a PADT frame is sent to each peer to make certain that theyare aware the session has been killed..SH EXAMPLE INVOCATIONS.nfpppoe-relay -C eth0 -S eth1.fiThe example above relays frames between PPPoE clients on the eth0 networkand PPPoE servers on the eth1 network..nfpppoe-relay -B eth0 -B eth1.fiThis example is a transparent relay -- frames are relayed between any mixof clients and servers on the eth0 and eth1 networks..nfpppoe-relay -S eth0 -C eth1 -C eth2 -C eth3.fiThis example relays frames between servers on the eth0 network andclients on the eth1, eth2 and eth3 networks..SH AUTHORS\fBpppoe-relay\fR was written by David F. Skoll <dfs@roaringpenguin.com>.The \fBpppoe\fR home page is \fIhttp://www.roaringpenguin.com/pppoe/\fR..SH SEE ALSOpppoe-start(8), pppoe-stop(8), pppoe-connect(8), pppd(8), pppoe.conf(5),pppoe(8), pppoe-setup(8), pppoe-status(8), pppoe-sniff(8), pppoe-server(8)