PPPoE Access Server Commands and Files

A service provider that offers DSL services or support to customers can use an access server that is running Solaris PPPoE. The PPPoE access server and client do function in the traditional client-server relationship. This relationship is similar to the relationship of the dial-out machine and dial-in server on a dial-up link. One PPPoE system initiates communications and one PPPoE system answers. By contrast, the PPP protocol has no notion of the client-server relationship. PPP considers both systems equal peers.

The commands and files that set up a PPPoE access server include the following:

• /usr/sbin/sppptun Command

• /usr/lib/inet/pppoed Daemon

• /etc/ppp/pppoe File

• /etc/ppp/pppoe.deviceFile

• pppoe.so Plugin

/usr/lib/inet/pppoed Daemon

The pppoed daemon accepts broadcasts for services from prospective PPPoE clients. Additionally, pppoed negotiates the server side of the PPPoE tunnel and runs pppd, the PPP daemon, over that tunnel.

You configure pppoed services in the /etc/ppp/pppoe and /etc/ppp/pppoe.device files. If /etc/ppp/pppoe exists when the system boots, pppoed runs automatically. You can also explicitly run the pppoed daemon on the command line by typing /usr/lib/inet/pppoed.

/etc/ppp/pppoe File

The /etc/ppp/pppoe file describes the services that are offered by an access server plus options that define how PPP runs over the PPPoE tunnel. You can define services for individual interfaces, or globally, that is, for all interfaces on the access server. The access server sends the information in the /etc/ppp/pppoe file in response to a broadcast from a potential PPPoE client.

The following is the basic syntax of /etc/ppp/pppoe:

global-options service service-name service-specific-options device interface-name

The parameters have the following meanings.

For additional options to /etc/ppp/pppoe, refer to the pppoed(1M) and pppd(1M) man pages.

A typical /etc/ppp/pppoe file might resemble the following.

Example 32-4 Basic /etc/ppp/pppoe File

device hme1,hme2,hme3
service internet
   pppd "name internet-server"
service intranet
   pppd "192.168.1.1:"
service debug
   device hme1
   pppd "debug name internet-server"

In this file, the following values apply.

/etc/ppp/pppoe.device File

The /etc/ppp/pppoe.device file describes the services that are offered on one interface of a PPPoE access server. /etc/ppp/pppoe.device also includes options that define how PPP runs over the PPPoE tunnel. /etc/ppp/pppoe.device is an optional file, which operates exactly like the global /etc/ppp/pppoe. However, if /etc/ppp/pppoe.device is defined for an interface, its parameters have precedence for that interface over the global parameters that are defined in /etc/ppp/pppoe.

The basic syntax of /etc/ppp/pppoe.device is as follows:

service service-name service-specific-options service another-service-name service-specific-options

The only difference between this syntax and the syntax of /etc/ppp/pppoe is that you cannot use the device option that is shown in /etc/ppp/pppoe File.

pppoe.so Plugin

pppoe.so is the PPPoE shared object file that must be invoked by PPPoE access servers and clients. This file limits MTU and MRU to 1492, filters packets from the driver, and negotiates the PPPoE tunnel, along with pppoed. On the access server side, pppoe.so is automatically invoked by the pppd daemon.

Using PPPoE and PPP Files to Configure an Access Server

This section contains samples of all files that are used to configure an access server. The access server is multihomed. The server is attached to three subnets: green, orange, and purple. pppoed runs as root on the server, which is the default.

PPPoE clients can access the orange and purple networks through interfaces hme0 and hme1. Clients log in to the server by using the standard UNIX login. The server authenticates the clients by using PAP.

The green network is not advertised to clients. The only way clients can access green is by directly specifying "green-net" and supplying CHAP authentication credentials. Moreover, only clients joe and mary are allowed to access the green network by using static IP addresses.

Example 32-5 /etc/ppp/pppoe File for an Access Server

service orange-net
     device hme0,hme1
     pppd "require-pap login name orange-server orange-server:"
service purple-net
     device hme0,hme1 
     pppd "require-pap login name purple-server purple-server:"
service green-net
     device hme1 
     pppd "require-chap name green-server green-server:"
     nowildcard

This sample describes the services that are available from the access server. The first service section describes the services of the orange network.

service orange-net device hme0,hme1 pppd "require-pap login name orange-server orange-server:"

Clients access the orange network over interfaces hme0 and hme1. The options that are given to the pppd command force the server to require PAP credentials from potential clients. The pppd options also set the server's name to orange-server, as used in the pap-secrets file.

The service section for the purple network is identical to the service section of the orange network except for the network and server names.

The next section describes the services of the green network:

service green-net device hme1 pppd "require-chap name green-server green-server:" nowildcard

This section restricts client access to interface hme1. Options that are given to the pppd command force the server to require CHAP credentials from prospective clients. The pppd options also set the server name to green-server, to be used in the chap-secrets file. The nowildcard option specifies that the existence of the green network is not advertised to clients.

For this access server scenario just discussed, you might set up the following /etc/ppp/options file.