Using Graphical Configuration Tools
Ubuntu provides options for desktop users to configure networking using
graphical configuration tools. In most cases, all you need to know is
contained in Chapter 1, “Installing Ubuntu and Post-Installation
Configuration,” in the section “Configuring Wireless Networks.” Power users
and unique setups generally eschew the GUI and use command-line tools.
Dynamic Host Configuration Protocol
As its name implies, Dynamic Host Configuration Protocol (DHCP) is used
to configure hosts for connection to your network. DHCP enables a network
administrator to configure all TCP/IP parameters for each host as she
connects them to the network after activation of a NIC. These parameters
include automatically assigning an IP address to a NIC, setting name server
entries in /etc/resolv.conf, and configuring default routing and
gateway information for a host. This section first describes how to use DHCP
to obtain IP address assignment for your NIC and then how to quickly set up
and start a DHCP server using Ubuntu.
NOTE
You can learn more about DHCP by reading RFC 2131, “Dynamic Host
Configuration Protocol,” at www.ietf.org/rfc/rfc2131.txt.How DHCP Works
DHCP provides persistent storage of network parameters by holding
identifying information for each network client that might connect to the
network. The three most common pairs of identifying information are as
follows:
Network subnet/host address—Enables hosts to connect to the network
at will
Subnet/hostname—Enables the specified host to connect to the subnet
Subnet/hardware address—Enables a specific client to connect to the
network after getting the hostname from DHCPDHCP also allocates to the client’s temporary or permanent network (IP)
addresses. When a temporary assignment, known as a lease, elapses, the
client can request to have the lease extended, or, if the address is no longer
needed, the client can relinquish the address. For hosts that will be