Tuesday, August 26, 2008

Configuring Wireless Ethernet Interfaces in Ubuntu

The Linux kernel includes drivers for many popular PCI wireless cards, PCMCIA wireless adapters, and USB wireless adapters. On Ubuntu systems, wireless Ethernet interfaces are configured in the same way as wired Ethernet interfaces.

If no Linux driver is available for your wireless card, all is not lost. Thanks to the cleverness of the folks in the open source community, a Linux kernel module and related utilities called ndiswrapper enables you to use the Microsoft Windows drivers for much of the networking hardware that is not yet natively supported by Linux. Installing these utilities, installing Windows drivers under Linux, and configuring your system to automatically start loading the kernel module.

Using systems that have both wired and wireless interfaces is quite common nowadays. Even though wireless specifications such as 802.11g and the upcoming 802.11n provide high communication speeds. Ubuntu’s administrative Networking application makes this easy enough to do manually, but an automated solution is also available in the Networking Manager application.

Wireless network adapters are configured in basically the same way as standard networking adapters, except that they require some additional, wireless-specific information. To configure a wireless networking adapter on your Ubuntu system, connect it to your system and select System -> Administration -> Networking to start Ubuntu’s networking administration application (which you can also execute as the network-admin command from any Ubuntu command line, using the sudo command).

When you first start this application, your wireless adapter should be listed in the dialog, but should be identified as being unconfigured. If no wireless adapter is listed, your wireless adapter may not be directly supported by the Linux kernel.

Once your wireless adapter is displayed in the dialog, select the entry for your adapter and click Properties to display the configuration dialog for wireless adapters. Select the Enable this interface checkbox to enable you to enter specific configuration information for your wireless interface.

If you want to join a specific wireless network, enter the ESSID of that network—leaving this space blank will enable your wireless interface to connect to any open, publicly visible access point that does not require authentication, regardless of its name. Similarly, if the wireless network that you are joining uses WEP keys, select the appropriate type of key from the Key type drop-down list, and enter the key in the WEP key field— if the wireless network that you want to join does not use WEP, leave the Plain (ASCII) key type selected, and leave the WEP key field blank. The final configuration step is to enter the appropriate networking information if you want your system to use a static IP address for its wireless connection. If the wireless network that you want to join uses DHCP, click the Configuration entry and select DHCP from the drop-down list.

After completing these settings, click OK to proceed. The Properties dialog closes, and a status dialog displays as your Ubuntu system activates your new wireless adapter.

If your system has both wired and wireless adapters and you want to be able to use both together, you should change the Default gateway device setting at the bottom of the dialog to identify the Ethernet device over which you want to send packets to random hosts. In most cases, this will be your wired network interface. Depending on your configuration, you may also want to disable the other Ethernet interfaces on your system by selecting each interface, clicking Properties, and deselecting the Enable this connection checkbox.

To complete the wireless configuration process, you can then click OK to save your configuration settings, or click Cancel to close this dialog without saving any of your new configuration settings. You can verify that the interface is correctly configured by using the ifconfig command to query the status of that interface from any Ubuntu command line, which displays output like the following:

$ ifconfig wlan0
wlan0 Link encap:Ethernet HWaddr 00:06:25:07:F7:0E
inet addr: Bcast:
inet6 addr: fe80::206:25ff:fe07:f70e/64 Scope:Link
RX packets:44 errors:0 dropped:0 overruns:0 frame:0
TX packets:14 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:7697 (7.5 KiB) TX bytes:1284 (1.2 KiB)

Some removable wireless Ethernet interfaces are assigned names beginning with wlan (wireless LAN) and use numeric identifiers to differentiate between multiple wireless interfaces, just like Ethernet interfaces whose names typically begin with eth. The prefix used (wlan or eth) is set inside the device driver.

>>> Read more about Overview of Wireless Technologies <<<

Source of Information : Ubuntu Linux - Bible

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