27.5. Using PPP over ATM (PPPoA)

27.5. Using PPP over ATM (PPPoA)
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The following describes how to set up PPP over ATM (PPPoA). PPPoA is a popular choice among European DSL providers.

27.5.1. Using mpd

The mpd application can be used to connect to a variety of services, in particular PPTP services. It can be installed using the net/mpd5 package or port. Many ADSL modems require that a PPTP tunnel is created between the modem and computer.

Once installed, configure mpd to suit the provider's settings. The port places a set of sample configuration files which are well documented in /usr/local/etc/mpd/. A complete guide to configure mpd is available in HTML format in /usr/ports/share/doc/mpd/. Here is a sample configuration for connecting to an ADSL service with mpd. The configuration is spread over two files, first the mpd.conf:

Note:

This example of the mpd.conf file only works with mpd 4.x.

default:
    load adsl

adsl:
    new -i ng0 adsl adsl
    set bundle authname username 
    set bundle password password 
    set bundle disable multilink

    set link no pap acfcomp protocomp
    set link disable chap
    set link accept chap
    set link keep-alive 30 10

    set ipcp no vjcomp
    set ipcp ranges 0.0.0.0/0 0.0.0.0/0

    set iface route default
    set iface disable on-demand
    set iface enable proxy-arp
    set iface idle 0

    open

	The username used to authenticate with your ISP.
	The password used to authenticate with your ISP.

The mpd.links file contains information about the link, or links, to establish. An example mpd.links to accompany the above example is given beneath:

adsl: set link type pptp set pptp mode active set pptp enable originate outcall set pptp self 10.0.0.1

set pptp peer 10.0.0.138

The IP address of FreeBSD computer running mpd.

The IP address of the ADSL modem. The Alcatel SpeedTouch™ Home defaults to 10.0.0.138.

It is possible to initialize the connection easily by issuing the following command as root:

# mpd -b adsl

To view the status of the connection:

% ifconfig ng0
ng0: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> mtu 1500
     inet 216.136.204.117 --> 204.152.186.171 netmask 0xffffffff

Using mpd is the recommended way to connect to an ADSL service with FreeBSD.

27.5.2. Using pptpclient

It is also possible to use FreeBSD to connect to other PPPoA services using net/pptpclient.

To use net/pptpclient to connect to a DSL service, install the port or package, then edit /etc/ppp/ppp.conf. An example section of ppp.conf is given below. For further information on ppp.conf options consult ppp(8).

adsl:
 set log phase chat lcp ipcp ccp tun command
 set timeout 0
 enable dns
 set authname username 
 set authkey password 
 set ifaddr 0 0
 add default HISADDR

The password for your account.

Warning:

Since the account's password is added to ppp.confin plain text form, make sure nobody can read the contents of this file:

# chown root:wheel /etc/ppp/ppp.conf
# chmod 600 /etc/ppp/ppp.conf

This will open a tunnel for a PPP session to the DSL router. Ethernet DSL modems have a preconfigured LAN IP address to connect to. In the case of the Alcatel SpeedTouch™ Home, this address is 10.0.0.138. The router's documentation should list the address the device uses. To open the tunnel and start a PPP session:

# pptp address adsl

Tip:

If an ampersand (“&”) is added to the end of this command, pptp will return the prompt.

A tun virtual tunnel device will be created for interaction between the pptp and ppp processes. Once the prompt is returned, or the pptp process has confirmed a connection, examine the tunnel:

% ifconfig tun0
tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500
        inet 216.136.204.21 --> 204.152.186.171 netmask 0xffffff00
	Opened by PID 918

If the connection fails, check the configuration of the router, which is usually accessible using a web browser. Also, examine the output of pptp and the contents of the log file, /var/log/ppp.log for clues.

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