Fedora Linux

3.2.1.2. Using GNOME NetworkManager

The GNOME NetworkManager facility provides an alternative to the use of profiles. NetworkManager is a service that automatically detects network configuration changes and determines available options. A small GUI application permits you to quickly select the network option you wish to use. It's ideal for laptop users because it permits rapid switching between multiple wired and wireless networks.

At this time, NetworkManager is a work in progress. When it works, it works well, but some hardware that works fine with other configuration techniques does not work at all with NetworkManager. It is proposed that NetworkManager will eventually become the configuration tool of choice. 

The NetworkManager service is enabled in the same way as every other service (see Lab 4.6, 'Managing and Configuring Services '). You can configure it to start at the next boot by choosing the menu option System>Administration>Services, and then selecting the checkboxes labeled NetworkManger (the related NetworkManagerDispatcher service is not usually required); to start the services immediately, select each of them in turn and then click the Start button.

From the command line, you can start the service immediately using the service command, and you can configure it to start at boot time using chkconfig :

# service NetworkManager start
Setting network parameters...
Starting NetworkManager daemon: [ OK ]
# chkconfig NetworkManager on

Notice the nonstandard use of capital letters in the name NetworkManager. 

As soon as the NetworkManager starts, an icon should appear in your panel's notification area, which is shown in Figure 3-21 . This icon will indicate the type of IP connection currently in use. To switch to a different connection, click on the icon; a list of available connections will appear (including all broadcast local network names if you have a wireless card, plus a little signal-strength bar graph for each wireless network). Click on the network you wish to connect to, and NetworkManager will attempt to make the connection. You will be prompted to enter WEP or WPA encryption keys if necessary.

Figure 3-21. NetworkManager icon (left), showing that a wired Ethernet connection is active  

NetworkManager will establish connections with wired networks automatically, but it will not automatically connect to wireless networks to which you have not previously connected because they may belong to your neighbor, or to companies that you are passing if you are in a vehicle. It will also detect the loss of network connectivity when a wireless signal is no longer usable or a network cable is unplugged.

You can also view the NetworkManager status from the command line by using nm- tool :

# nm-tool
NetworkManager Tool
State: connected
- Device: eth0 ----------------------------------------------------------------
 NM Path: /org/freedesktop/NetworkManager/Devices/eth0
 Type: Wired
 Driver: b44
 Active: yes
 HW Address: 00:0D:56:33:D7:18
 Capabilities:
  Supported: yes
  Carrier Detect: yes
  Speed: 100 Mb/s
 Wired Settings
  Hardware Link: yes
 IP Settings:
  IP Address: 172.16.97.100
  Subnet Mask: 255.255.255.0
  Broadcast: 172.16.97.255
  Gateway: 172.16.97.254
  Primary DNS: 24.153.23.66
  Secondary DNS: 24.153.22.67

3.2.1.3. Configuring networking from the command line

The GUI network configuration tool and NetworkManager both work well for desktop users, but when you're logged in to a server that is a few time zones away or need to make a fast change, it's useful to be able to configure networking from the command line.

The main interface configuration command is ifconfig (for interface configuration ). Executed by itself, it displays the basic configuration of active interfaces:

$ /sbin/ifconfig
eth0 Link encap:Ethernet HWaddr 00:0D:56:33:D7:18
      inet addr:172.16.97.100 Bcast:172.16.97.255 Mask:255.255.255.0
      inet6 addr: fe80::20d:56ff:fe33:d718/64 Scope:Link
      UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
      RX packets:289 errors:0 dropped:0 overruns:0 frame:0
      TX packets:228 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:1000
      RX bytes:45844 (44.7 KiB) TX bytes:27193 (26.5 KiB)
      Interrupt:177
lo    Link encap:Local Loopback
      inet addr:127.0.0.1 Mask:255.0.0.0
      inet6 addr: ::1/128 Scope:Host
      UP LOOPBACK RUNNING MTU:16436 Metric:1