You should only need to use these steps if you are using a modem supplied by your ISP, and not a router. The basic steps involved in manually setting up a DSL connection using Ubuntu involve connecting the proper hardware, and then running a simple configuration script if you use rp-pppoe from Roaring Penguin.
First, connect your DSL modem to your telephone line, and then plug in your ethernet cable from the modem to your computer's network interface card. If you plan to share your DSL connection with the rest of your LAN, you need at least two network cardsdesignated etho (for your LAN) and etHi (for the DSL connection).
The following example assumes that you have more than one computer and will share your DSL connection on a LAN.
First, log in as root, and ensure that your first etho device is enabled and up (perhaps using the ifconfig command). Next, bring up the other interface, but assign a null IP address like this:
$ sudo /sbin/ifconfig eth1 0.0.0.0 up
Now use the adsi-setup command to set up your system. Type the command like this: $ sudo /sbin/adsl-setup
You will be presented with a text script and be asked to enter your username and the Ethernet interface used for the connection (such as ethi). You will then be asked to use "on demand" service or have the connection stay up all the time (until brought down by the root operator). You can also set a timeout in seconds, if desired. You'll then be asked to enter the IP addresses of your ISP's DNS servers if you haven't configured the system's /etc/resoiv.conf file.
After that, you will be prompted to enter your password two times, and have to choose the type of firewall and IP masquerading to use. (You learned about IP masquerading in the "Using IP Masquerading in Ubuntu" section, earlier in this chapter.) The actual configuration is done automatically. Using a firewall is essential nowadays, so you should choose this option unless you intend to craft your own set of firewall rulesa discussion of which is beyond the scope of this book. After you have chosen your firewall and IP masquerading setup, you will be asked to confirm, save, and implement your settings. You are also given a choice to allow users to manage the connection, a handy option for home users.
Changes will be made to your system's /etc/sysconfig/network-scripts/ifcfg-pppO, /etc/resolv.conf, /etc/ppp/pap-secrets, and /etc/ppp/chap-secretsfiles.
After configuration has finished, use the adsi-start command to start a connection and DSL session, like this:
$ sudo /sbin/adsl-start
The DSL connection should be nearly instantaneous, but if problems occur, check to make sure that your DSL modem is communicating with the phone company's central office by examining the status LEDs on the modem. Because this varies from modem to modem, consult your modem user's manual.
Check to make certain that all cables are properly attached, that your interfaces are properly configured, and that you have entered the correct information to the setup script.
If IP masquerading is enabled, other computers on your LAN on the same subnet address (such as 192.I68.1.xxx) can use the Internet, but must have the same /etc/resolv.conf name server entries and a routing entry with the DSL-connected computer as a gateway. For example, if the host computer with the DSL connection has an IP address of 192.168.1.1, and other computers on your LAN use addresses in the 192.168.1.xxx range, use the route command on each computer like this:
# /sbin/route add default gw 192.168.1.1
Note that you can also use a hostname instead if each computer has an /etc/hosts file with hostname and IP address entries for your LAN. To stop your connection, use the adsl-stop command like this:
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