In Ubuntu, the graphical configuration tool to configure network interfaces is called network-admin. This is an alternative to using nm-applet (GNOME front end for NetworkManager).
nm-applet does not use the standard NetworkAdmin file /etc/network/interfaces to store the Wireless Network settings, so you will not be able to use ifup and ifdown commands to start/stop network adapters. This can make it more difficult to diagnose connection problems.
In Ubuntu 8.10 (Intrepid Ibex) and newer, install the package gnome-network-admin through Synaptic, or through the terminal with:
sudo apt-get install gnome-network-admin
In Ubuntu 8.04 (Hardy Heron), network-admin is installed by default and is part of the gnome-system-tools package. No installation steps are required.
There are two ways to start network-admin:
Type network-admin into a terminal.
From your menu bar, go to System->Administration->Network
You will need to click the Unlock button and enter your password to make changes (assuming you have admin/sudo privileges on your user account - see RootSudo).
If you are using a dialup modem, see here.
Wired connections generally work out of the box, but if the connection fails, select your "Wired connection" and hit the Properties button. Now check the box for "Enable roaming mode".
Wireless connections can prove a little more tricky, and are usually easily configured using nm-applet from the tray area. If you would rather use this method, select "Wireless connection" and hit the Properties button. Enter your wireless network's ESSID and WEP/WPA password (if applicable). Under Connection Settings, you will most likely want to select "Automated Configuration (DHCP)" for the "Configuration" option.
The preferred method is to "Enable roaming mode" - this often fixes problems when trying to connect to networks using nm-applet.
Please consult your router's manual for help with accessing router configuration pages, which may be needed for using advanced networking options. Most of these are available in PDF format online, just Google your router's make/model.
Static IP address
This applies to both wired and wireless network settings. First, be sure that roaming mode is disabled. I have provided you with an example using a Linksys router, but every make and model router can be a little different:
Configuration: Static IP Address
IP address: 192.168.1.200 - the last octet of the IP address should usually be between 150 and 255, which is outside the DHCP range of a standard Linksys router.
Subnet mask: 255.255.255.0
Gateway address: 192.168.1.1 - this is usually your router's internal IP address.
Here you can set your computer's Host name and Domain name. These are needed when sharing files, folders, and printers between computers on a network. All computers should be on the same domain, and your host name is your computer's unique identifier.
Most people will not want to fiddle with this unless they are using their own DNS servers, or their computer is not auto-detecting them. Since this varies between ISPs and networks, we will not cover examples here.
This is data stored in the /etc/hosts file. Here is a generic example, most computers will have very similar values:
127.0.0.1 localhost 127.0.1.1 your_computer_name ::1 ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters ff02::3 ip6-allhosts
Storage of Profiles And Settings
network-admin stores information about different Profiles in the following directory:
During startup, the system will activate the network interfaces stored in the file /etc/network/interfaces.
A very good place to begin is by restarting the networking service:
sudo /etc/init.d/networking restart
Another good method is to stop/restart the network interface(s) from the terminal, one at a time, which shows some diagnostic messages. wlan0 is used as an example, but this applies to all interfaces:
sudo ifdown wlan0 sudo ifup wlan0
You may also diagnose the network adapter status with commands:
ip addr; ip route show table all; ip rule; iwconfig dmesg tail /var/log/messages
Ask for Help
The Ubuntu Forums provide great community support, so check out the Networking & Wireless area of the forums.
- Network Manager:
Ubuntu 8.10 (Intrepid Ibex) and newer: NetworkManager0.7
Ubuntu 8.04 (Hardy Heron) and older: NetworkManager
Getting Support: Ubuntu Forums: Networking & Wireless