It s All Fun and Games until Something Doesn t (Web file server)
It s All Fun and Games until Something Doesn t WorkIn a perfect world, the dial-up configuration steps in the preceding sectionwould work 100 percent of the time. The Linux vendors have truly hidden allthe mystery that has traditionally surrounded networking. Unfortunately, inmany situations (mostly related to modems and hardware), a simplified con- figuration doesn t work. If you can t connect to the Internet after followingthese steps, an excellent site to find help is LinuxQuestions.org (www.linuxquestions.org). It s simply impossible for me to anticipate the wide rangeof problems people can run into, and this site is well known for its helpfulcommunity members. Also, go to your favorite Web search site and search on the error messageyou re getting from the system, or some keywords involved with the error, such as the network hardware s make and model, and the name of your distribution. You can use two cool tools when you re trying to figure outwhat s wrong with your network connection or trying to gather informationthat can help someone else figure out what s wrong: the handy command lineprograms pingand traceroute. Together, you can use these commands tofigure out where the problem might be when you can t reach something overa network. These commands are discussed in the next two sections. Some firewalls block the kind of traffic sent with pingsand traceroutes, sothese commands don t always work as expected, even with a good connection. Checking whether you can talk to a specific address with pingThe pingcommand is akin to a submarine using sonar to detect otherobjects in the ocean. Sonar sends out a pingsignal, which reflects off a hardsurface. By measuring the amount of time between sending the pingand theping s return, the submarine s engineer can determine whether an object isout there and how far from the submarine the object is. The pingcommand in Linux provides information similar to what sonar pro- vides. If you consider the Internet to be your ocean, you can determine, bypinging, what other network computers exist and also how long it takes foryour pingto return. You use this command in the format ping hostnameorping ipaddress, such as ping bob.example.comor ping 192.168.1.5. Ifyou can t ping another computer in your house or office (assuming that youhave them all connected with Ethernet and not on separate dial-up connec- tions), then something is wrong with the machine you re pinging from. On the161Chapter 8: Connecting to the Internet13_