some way.
This chapter covers network and Internet connectivity, as most networks
invariably end up connected to the Internet in some shape or form. You learn
how to get the basics right, including configuration and management of
network interface cards (NICs) and other network services with Ubuntu. You
also find out how to manage network services from the command line—
which is important in case you are ever confined to a command prompt. We
also look at connectivity options, both for inbound- and outbound-network
traffic, such as Point-to-Point Protocol (PPP).
We focus on the use of text interfaces and manual configurations in this
chapter. We also include an overview of basic graphical network management
in Ubuntu, which is becoming more and more popular. The graphical user
interface (GUI) option has become much more stable, useful, and easy to
comprehend, and most desktop users now use the GUI to interact with
networking. However, this is a book for power users who want to learn about
the guts of their system, so roll up your sleeves and prepare to get your hands
dirty.
Laying the Foundation: The localhost
Interface
The first thing that needs to be in place before you can successfully connect to
the Internet or any other network is a localhost interface, sometimes
called a loopback interface, and commonly referenced as lo. The TCP/IP
protocol suite (see the section “Networking with TCP/IP,” later in this
chapter) uses this interface to assign an IP address to your computer and is
needed for Ubuntu to establish a PPP interface.
Checking for the Availability of the Loopback
Interface
You should not normally have to manually create a loopback interface
because Ubuntu creates one automatically for you during installation. To
check that one is set up, you can use the ip command with a couple
parameters to list all networking interfaces available, including the lo
interface if it exists. This example shows only the information for lo:
Click here to view code image
matthew@seymour:~$ ip address show