Internet Dial-up Setup



Different distributions let you configure your internet connection differently. Graphical setup tools are now becoming quite popular. This guide lets you set up a basic internet connection using the pppsetupprogram that comes with the the ppp package. Despite what fancy tools may be used to set up and start the internet connection, and the end of the day, pppd and the tools that come with it are used to create the actual connection. All the graphical tools are just fancy frontends.

pppd and chatwill be discussed here. An alternative way of setting up an internet connection is to use wvdial available at freshmeat. wvdial is a replacement for chat, and is considered to be an "intelligent" dialer. The configuration is much simpler than with chat and usually all you need to provide it with are the telephone number to dial, your username and password. The /etc/ppp/options file will still have to be created however, and pppsetup can be used for this.

Setting Up The Connection

  • To set up a connection, the ppp software must be installed on your system, which most distributions do. Also, you must have ppp support in the kernel (or as a module). Again, most kernels that come with popular distributions have this support. If you need to enable it manually, you'll have to recompile your kernel, or at least a few modules. The Kernel HOWTO explains how to do this.

  • As root, run pppsetup.You will be asked several questions. Some of the questions and answers are covered in Table 1 below. Once all the questions have been answered, ppp configuration files are generated and stored in /etc/ppp.
  • /etc/ppp/optionsis the file to initialize pppd and /etc/ppp/pppscript is used to communicate with the modem, send it initialization strings, dial out and so on.
  • Linux does not use "modem drivers." Instead, the serial port needs to be configured correctly, and the default setup usually works just fine so it's unlikely you will have to make any changes in that regard.


Table 1: pppsetup questions and descriptions/answers

Phone Number
 Enter your phone number. For the phone number 12345, enter it as ATDT12345 for a tone dial phone and ATDP12345 for the old pulse dial phones. Most people now have tone dial phones.
Initialization String
 The default is "AT&FH0" OK. This is called an expect-send pair, where "AT&FH0" will be sent to the modem, and "OK" will be received (actually, this is the send part of one command and the expect part of another, so really it's a send-expect pair). When specifying initialization strings, make sure to specify both the string AND the expected response. The resonse is usually "OK". (one of the things that makes wvdial nice is that there's no need to worry about responses)

To simply reset the modem instead of sending it a special initialization string, try "ATZ" OK.

A conservative string that has always worked for me is "AT&FX3&C1&D2" "OK".

Most modems are happy with any of the initialization strings above. Some (eg. Creative's Modem Blaster 28.8) are much fussier. If your modem is connected to the correct serial port but still refuses to respond, it very likely requires a specialized initialization string. Refer to the manual or google for more details.
PAP or CHAP
 Most ISPs use PAP



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