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16 – Networking
When it comes to networking, there is probably nothing that cannot be done with Linux. Linux is used to build all sorts of networking systems and appliances, including firewalls, routers, name servers, NAS (Network Attached Storage) boxes and on and on.
Just as the subject of networking is vast, so are the number of commands that can be used to configure and control it. We will focus our attention on just a few of the most fre- quently used ones. The commands chosen for examination include those used to monitor networks and those used to transfer files. In addition, we are going to explore the ssh program that is used to perform remote logins. This chapter will cover:
● ping - Send an ICMP ECHO_REQUEST to network hosts
● traceroute - Print the route packets trace to a network host
● ip - Show / manipulate routing, devices, policy routing and tunnels
● netstat - Print network connections, routing tables, interface statistics, mas- querade connections, and multicast memberships
● ftp - Internet file transfer program
● wget - Non-interactive network downloader
● ssh - OpenSSH SSH client (remote login program)
We’re going to assume a little background in networking. In this, the Internet age, every- one using a computer needs a basic understanding of networking concepts. To make full use of this chapter we should be familiar with the following terms:
● IP (Internet Protocol) address
● Host and domain name
● URI (Uniform Resource Identifier)
Please see the “Further Reading” section below for some useful articles regarding these terms.
16 – Networking
Note: Some of the commands we will cover may (depending on your distribution) require the installation of additional packages from your distribution’s repositories, and some may require superuser privileges to execute.