This section explains how to use Neat to configure TCP/IP networking. If your system is not part of a LAN, you won’t generally need to perform the operations this section describes; establishing a PPP connection with your ISP generally configures your system’s network settings automatically. However, if you wish to customize your system’s network settings, or if you wish to better understand how Linux networking functions, you’ll find this information helpful.
To launch Neat, choose Programs → System → Network Configuration from the GNOME main menu, or System → Network Configuration from the KDE main menu. The Network Configuration dialog box, as shown in Figure 11-1, appears.
The dialog box has four tabs:
Hardware
Devices
Hosts
DNS
Each of these tabs is explained in a following section.
The Hardware tab of the Network Configuration dialog box shows the network devices found in your system, including network adapters and modems. You can use the controls appearing on the tab to specify information pertaining to network devices. To do so, highlight the desired device and click Edit. A configuration dialog box appears. The format of the dialog box depends on the type of network device selected.
Figure 11-2 shows a dialog box associated with a network adapter. This dialog box lets you specify the IRQ, memory address, DMA port, and other information associated with the network adapter. The PCI bus of a modern PC can generally probe for this sort of information automatically. Consequently, you probably won’t often find it necessary to use the Hardware tab. However, if your system is unable to detect an installed network device, you may be able to get the device working by entering the appropriate information in the configuration dialog box. To determine the proper information, inspect your system’s Windows configuration and consult documentation associated with the network device.
The Devices tab of the Network Configuration dialog box lets you configure network devices. Like the Hardware tab, it displays a list of devices. To configure a device, highlight the device and click Edit. A configuration dialog box appropriate to the type of the selected device appears. Figure 11-3 shows the Ethernet Device dialog box associated with a network adapter. The dialog box has three tabs, each of which is explained in a following subsection:
General
Protocols
Hardware Device
The General tab of the Ethernet Device dialog box lets you perform the following operations:
- Specify a nickname for the device
By default, Ethernet devices have nicknames such as eth0, eth1, and so on. Generally, you should not change the nickname associated with an Ethernet device.
One circumstance in which you may wish to change the nickname occurs when you change the relative position of network adapters on your system’s PCI bus. Doing so causes the device previously known as eth0 to become known as eth1 and vice versa. Rather than reconfigure networking, you can change the nickname associated with each device, so that the original network configuration is once again correct.
- Specify that the device should be activated when the computer starts
Generally, Ethernet devices should be configured so that they’re activated when the computer starts. You may wish to change this specification when troubleshooting or in order to temporarily deactivate a device.
- Specify that any user can enable or disable the device
Generally, only the root user should be permitted to enable or disable a network device. The root user is presumed to be capable of exercising judgment that prevents, for example, unnecessarily disabling a device that other users are using.
However, you may wish to assign this privilege to trusted users who will exercise it appropriately. This is seldom necessary for Ethernet devices but may be useful for PPP devices. Allowing a user to enable a PPP device enables the user to establish an Internet connection without the assistance of the root user.
The Protocols tab of the Ethernet Device dialog box lets you configure TCP/IP options pertaining to the device. To do so, highlight TCP/IP and click Edit. The TCP/IP Settings dialog box, as shown in Figure 11-4, appears.
The TCP/IP Settings dialog box has three tabs:
TCP/IP
Hostname
Routing
Every Internet host has an associated identifier known as an IP address. As shown in Figure 11-4, the TCP/IP tab lets you specify how the IP address associated with the Ethernet device is obtained. If the device is associated with a network that includes a server that provides IP address information to clients, the IP address can be obtained automatically. To enable this feature, check the box labeled “Automatically obtain IP address settings with.” Then, use the drop-down list box to specify the type of server, which can be any of the following:
DHCP (Dynamic Host Configuration Protocol)
Bootp (boot protocol)
Dialup
You should consult your network administrator to determine whether the network includes an appropriate server and the type of server, if any. Generally, the server will use the DHCP protocol. Some Unix servers provide information via the Bootp protocol. The Dialup option is not appropriate for Ethernet adapters; however, it is often specified for PPP devices.
If no server is available, you can specify your system’s IP address manually. Consult your network administrator to determine the proper values. Uncheck the box labeled “Automatically obtain IP address settings with” and specify the following information:
- Address
Specify the IP address associated with the network adapter. An IP address consists of four numbers, separated by dots, for example, 192.168.1.1.
- Subnet Mask
Specify the network mask that identifies the part of the adapter’s IP address that represents the network address. If you’re uncertain what value to use, try the value 255.255.255.0, which works in most cases.
- Default Gateway Address
Specify the IP address of the system that forwards packets from the network to the outside world. If your system connects to the Internet via a dialup connection, leave this field blank.
If you’re setting up your own network, you can use the IP numbers from 192.168.1.1 to 192.168.1.254 to identify your systems. These numbers are one of several sets of IP addresses set aside for private use.
Figure 11-5 shows the Hostname tab of the TCP/IP Settings dialog box. This tab lets you specify a hostname by which your system is known. The hostname you specify is known only to your system; unless you configure a DNS server, which is a demanding task, your system will be known to other systems only by its IP address.
The Hostname tab also lets you specify how your system obtains DNS information, which it uses to determine the IP address associated with a hostname. If a DHCP server on the network provides the IP address of a DNS server, you can check the box labeled “Automatically obtain DNS information from provider.”
If your network connects to other local area networks, you must identify these networks in order to be able to access hosts on them. To do so, use the Routing tab of the TCP/IP Settings dialog box, shown in Figure 11-6.
To identify a local network, click Add. A dialog box lets you specify the IP address and subnet mask of the network and the IP address of the system that acts as the gateway to the network.
The Hardware Device tab of the Ethernet Device dialog box, shown in Figure 11-7, lets you specify special hardware device options. These options are seldom needed except in sophisticated network configurations.
It’s possible to associate multiple IP addresses with a single network device. Addresses other than the primary address are called aliases. You can create an alias by checking the box labeled Enable Device Alias Support and specifying the device and alias.
You can also specify the hardware or Media Access Control (MAC) address associated with an Ethernet device, overriding the value specified at the time of manufacture. To do so, check the box labeled Use Hardware Address and specify the desired hardware address.
Most systems attached to a network use DNS services to determine the IP address associated with a hostname. However, you can configure your system to determine the IP address associated with a hostname even when DNS services are not available. To do so, use the Hosts tab of the Network Configuration dialog box, shown in Figure 11-8.
Figure 11-8. The Hosts tab of the Network Configuration dialog box and the Add/Edit Hosts Entry dialog box
To specify host information, click Add and supply the IP address and name of the host. If desired, you can specify one or more aliases or abbreviated names for the host. By default, the host information includes an entry for the IP address 127.0.0.1, which is associated with the hostname localhost. You should not disturb this entry, which provides a way for your system to access its own network facilities.
The DNS tab of the Network Configuration dialog box, shown in Figure 11-9, lets you specify options that govern how your system determines IP addresses from hostnames. The tab lets you specify the following information:
- Hostname
The hostname of your system, including the domain name. By default, the hostname is
localhost.localdomain. You should change this value only if your system has a hostname registered with a DNS server.- Domain
The domain name of your system. By default, the domain name is
localdomain. You should change this value only if your system has a hostname registered with a DNS server.- Primary DNS
The IP address of the DNS server, if any, your system should use. If a DHCP server provides your system with its network configuration, you may omit this value.
- Secondary DNS
The IP address of a backup DNS server, if any, that your system should use if the primary DNS server is unavailable. If a DHCP server provides your system with its network configuration, you may omit this value.
- Tertiary DNS
The IP address of a second backup DNS server, if any, that your system should use if the primary and secondary DNS servers are unavailable. If a DHCP server provides your system with its network configuration, you may omit this value.
- DNS Search Path
If you frequently access other hosts on your ISP’s network, you should specify a search domain, for example,
oreilly.com. Doing so enables you to refer to the hostabc.oreilly.com, for example, as simplyabc. To do so, type the domain name in the text box labeled Search Domain and click Add. If you like, you can specify multiple domains, which are searched in the order specified, from top to bottom. You can use the Up and Down buttons to reorder the domains.
