Dialup to the Internet (you poor soul)

Sometimes you're stuck with dialup access. Or maybe you just want to have a backup link for your cable or DSL connection. Either way, you need to be able to set up a modem under Linux.

Luckily, it's much easier than it used to be to get your modem connection running. The first question thing you need to figure out is what kind of modem you have. If it's an external modem, you're good to go. If it's an internal, there's some things you need to figure out.

The first issue is Winmodems. If your computer has one of the aberrations of nature, you will not be able to use it in Linux. A Winmodem offloads most of the modem functionality that would run in hardware with a normal modem onto the processor of your PC. They are completely proprietary. If you have a PCI modem,chances are it's a winmodem. If it's an ISA modem, you may be lucky enough to have jumpers on the card to set up your COM port and IO address. If it's a PnP ISA card, you will have to use isapnp to set up these parameters. Most modern Linux distributions will handle this "out of the box". So unless you've got something really old and esoteric or you've got a PCI Winmodem, you're good to go. And if you're not, finding an external modem cheap shouldn't be too hard.

The easiest way to check for a modem is via your trusty command line. Enter the command dmesg | grep tty and you'll see something like this:

ttyS00 at 0x03f8 (irq = 4) is a 16550A ttyS01 at 0x02f8 (irq = 3) is a 16550A tty03 at 0x03e8 (irq = 3) is a 16550A

In Linux, our COM ports have a different naming convention. COM1 in windows is /dev/ttyS00 in Linux. COM2 is /dev/ttyS01, etc. etc. In the listing above, I have three such ports listed. On the back of my box is two serial ports, so the third port is my modem. woohoo.

The more you know about your modem when you start, the better off you'll be. The nice thing about Linux these days is that most distributions can set up a dialup to an ISP as easily as windows. KPPP, gnome's PPP setup, Redhat netconfig, and debian's pppconfig all mimic Windows' Internet connection wizard. They will attempt to detect your modem and usually succeed. They will then ask for your username, password, and phone number. And that's about it. At one time, you had to worry about scripting your connection to match prompts from your ISP's servers. Now most ISP's use PAP authentication so this step is standardized. If you're in doubt, try PAP first and use your distribution's PPP setup utility's debug window to watch the connection progress.

In an attempt to be more versatile some of the Linux utilities have lots of additional options for setting static IPs, scripting connections, etc. Don't try these options unless you're absolutely sure you need them. Do everything dynamically and allow your ISP to assign your address, set your default route, and even set up your nameservers. Unless your ISP is really, really dumb, it will work as easily under Linux as it does with Windows. Be happy because this used to be much, much harder to do.