Chapter 13 Basic Network Commands

Table of Contents
13.1 ping
13.2 traceroute
13.3 DNS Tools
13.4 finger
13.5 telnet
13.6 The Secure shell
13.7 email
13.8 Browsers
13.9 FTP Clients
13.10 Talking to Other People

A network consists of several computers connected together. The network can be as simple as a few computers connected in your home or office, or as complicated as a large university network or even the entire Internet. When your computer is part of a network, you have access to those systems either directly or through services like mail and the web.

There are a variety of networking programs that you can use. Some are handy for performing diagnostics to see if everything is working properly. Others (like mail readers and web browsers) are useful for getting your work done and staying in contact with other people.

13.1 ping

ping(8) sends an ICMP ECHO_REQUEST packet to the specified host. If the host responds, you get an ICMP packet back. Sound strange? Well, you can “ping” an IP address to see if a machine is alive. If there is no response, you know something is wrong. Here is an example conversation between two Linux users:

User A: Loki's down again.
User B: Are you sure?
User A: Yeah, I tried pinging it, but there's no response.

It's instances like these that make ping a very useful day-to-day command. It provides a very quick way to see if a machine is up and connected to the network. The basic syntax is:

% ping

There are, of course, several options that can be specified. Check the ping(1) man page for more information.