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FreeBSD Basics

Connecting to the Internet Using PPP or a Cable Modem

06/14/2000

"Why do I need to configure a connection to the Internet?"

One of the first things every new FreeBSD user wishes to do is set up a connection to the Internet. It can be overwhelming to be thrust into the world of PPP chat scripts and DHCP, especially if these terms are unfamiliar to you. I'll start today's article with some definitions of common terms and explain how these terms interrelate when you connect to the Internet. Then I'll show you how easy it is to do a basic Internet connection with FreeBSD, and leave you with some references should you wish to try more complicated configurations.

In order for two computers to exchange information, they need a connection between them, a physical device to handle the connection, and a protocol to package the data in a format both computers understand.

If the computers are physically located near each other, they will most likely be cabled together with either CAT-5 or coaxial cable to produce a LAN (Local Area Network). CAT-5 cable looks like the wire that plugs into your telephone jack, except that the connection at the end is bigger. Coaxial cable looks like cable-TV wiring. Both types of wiring will be attached to a NIC (Network Interface Card) at the back of each computer in the LAN. The NIC is responsible for transmitting electrical signals onto the wiring; these signals represent the data that the computers wish to exchange. As long as both computers are using the same protocol (rules of communication), they will be able to correctly translate the electrical signals back into the original data.

However, when you're connected to the Internet, you are really accessing other computers over a WAN (Wide Area Network). There is no way of knowing whether your data is travelling over CAT-5 cable, fiber optic cable, or transmissions from satellite links. Major telecommunications companies (e.g., MCI) control these links; you need an access point into this global network of telecommunication links. The most common way of gaining this access is through an account with either an ISP or a cable provider.

ISPs (Internet Service Providers) sell monthly access to the Internet; you access an ISP by dialing into their POP (Point of Presence) using a dial-up modem and your existing phone line or the PSTN (Public Switched Telephone Network). A modem is required to translate the digital signals used by your computer into the analog signals the telephone cabling in your home understands. Because you are dialing into another modem at the ISP using a temporary point to point connection, you need to configure the point to point protocol (PPP).

You don't need to configure PPP if you are using a cable modem, as you already have a constant connection to your cable provider. In essence, the cable modem is a "virtual" NIC connected to a very big "virtual" LAN. The cable modem does the necessary translation to make this work.

Before configuring PPP

Before configuring PPP, you need to know the following:

  • the COM (communications) port your modem is physically attached to
  • the phone number of your ISP's POP
  • the username and password the ISP provided you

Note, not all modems are created equal. Some modems require built-in software to work; unfortunately, this software only works on Windows computers, hence the nickname Winmodems. For more information on Winmodems, and to see if your modem is supported, try the Winmodems Are Not Modems page.

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