Many software modems do not work with Linux because the manufacturers
do not release programming information about them or provide Linux
drivers. External serial port modems or ISA bus modems almost always
work; USB and PCI modems are still problematic. It is suggested that you
do a thorough Google search, using your modem’s name and model
number, to see how others have solved problems with a particular modem.
Links to software modem compatibility sites appear at the end of this
chapter.Troubleshooting Connection Problems
The Linux Documentation Project at (www.tldp.org) offers many in-depth
resources for configuring and troubleshooting connection problems. Google is
also an invaluable tool for dealing with specific questions about connections.
For many other useful references, see the “References” section at the end of
this chapter.
Here are a few troubleshooting tips culled from many years of experience:
If your modem connects and then hangs up, you are probably using the
wrong password or dialing the wrong number. If the password and phone
number are correct, it is likely an authentication protocol problem.
If you get connected but cannot reach websites, it is likely a domain
name resolver problem, meaning that DNS is not working. If it worked
yesterday and you haven’t “adjusted” the associated files, it is probably a
problem on the ISP’s end. Call and ask.
Always make certain that everything is plugged in. Check again (and
again).
If the modem works in Windows but not in Linux no matter what you do,
it is probably a software modem no matter what it said on the box.
If everything just stops working (and you do not see smoke), it is
probably a glitch at the ISP or the telephone company. Take a break and
give them some time to fix it.
Never configure a network connection when you have had too little sleep
or too much caffeine; you will just have to redo it tomorrow.
RELATED UBUNTU AND LINUX COMMANDS
Use these commands when managing network connectivity in your Ubuntu
system:
dhclient—A tool for automatically acquiring and setting IP info for a