Network Configuration with Linuxconf

The first thing to determine when getting hooked up is whether you're connecting to a local area network, such as a group of computers in an office, or a wide area network, such as the Internet. Before continuing, it's important to know what hardware you have and how you intend to connect. If you're going to dial into another computer, make sure your modem is installed and that the cables are attached correctly. If you're using a network card, make sure it is installed properly and that the cables are correctly connected. In other words, no matter what network configuration you specify, if every phone line or cable is not in place, you'll never get connected.

Network Connections

Setting up a network connection over Ethernet requires an entirely different type of setup. Network connections to Token Ring or ARCnet networks follow a similar procedure, but will not be discussed here.

Figure 14-11. Adaptor 1

The first item on this screen is a checkbox to indicate whether this adaptor is enabled or not. If this is the one you intend to use, it should be checked. Below that is a choice of Config modes. Manual means that you will be providing all the information and entering it yourself. Dhcp and Bootp mean that your machine will be getting its network configuration information from a remote DHCP or BOOTP server. If you're not sure what option to choose, talk to your network administrator.

Required fields for DHCP or BOOTP:

For DHCP and BOOTP configurations, you only need to specify the Net device and the Kernel module. For the Net device, you will choose from a list in which the eth prefix represents Ethernet cards, arc specifies an ARCnet card and tr specifies Token Ring cards. A complete list of network cards and their respective modules can be found in Official Red Hat Linux Reference Guide. For the most up-to-date list, please see our website at:

The netmask information may be already be set for you. However, depending upon the type of network you are joining or setting up, you may need to fill in this field. The most common value for this field is

Required fields for manual configuration:

Information on network devices and kernel modules is described above. The appropriate Primary name + domain and IP address will depend on whether you are adding the computer to an existing network or creating a new network. For connecting to an existing network, contact your network administrator for the information.

If you're setting up a private network that will not ever be connected to the Internet, then you can choose any Primary name + domain name you want and you have several choices for IP addresses (see Table 14-1).

Table 14-1. Addresses and Examples

Available addresses Examples - -, - [a]
a. You should not use these IP addresses if you connect to the Internet, since 192.168.0.* and 192.168.255.* cannot be considered private. If you want your network to be connected to the Internet, or think you might want to at some point in the future, do yourself a favor and get yourself non-private addresses now.

The three sets of numbers above correspond to class a, b, and c networks respectively. The classes are used to describe the number of IP addresses available as well as the range of numbers. The numbers above have been set aside for private networks.

Name Server Specification

A nameserver and a default domain are also needed to establish a network connection. The nameserver is used to translate hostnames, such as, to corresponding IP addresses, such as

The default domain tells the computer where to look if a fully qualified hostname is not specified. "Fully qualified" means that the full address is given, so is the fully qualified hostname, while the hostname is simply foo. If you specified your default domain as, then you could use just the hostname to connect successfully. For example ftp foo would be sufficient if your search domain is, while ftp would be required if it was not.

To specify the nameserver, open Config => Networking => Client tasks => Name server specification (DNS).

Figure 14-12. Resolver Configuration Screen

Nameservers are ranked according to the order in which they are accessed. It is not unusual to see nameservers referred to as primary, secondary, tertiary and so on down the list if more than one is specified. Each of these must be an IP address and not a name, since the computer has no way to resolve the name until it connects to a nameserver.

In addition to a default domain, you can also specify up to six search domains. Search domains are useful if you want to specify many hostnames with the same domain but do not want to type the domain name. For example, if your search domain is, the hostname falcon would resolve to Search domains take precedence over the default domain.

You can add, modify, or delete entries from the /etc/hosts file using Linuxconf. Open Config => Networking => Misc => Information about other hosts.

Figure 14-13. /etc/hosts Screen

To modify or delete an entry select it. To delete the entry, select Del at the bottom of the host/network definition screen.

To modify it, change the information as necessary. To add a new entry, select Add at the bottom of the /etc/hosts screen. This will also open the host/network definition screen.

Required fields:

Optional fields:

Once finished, select Accept.