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Mine is a Wipro Little Genius laptop, Model WLG7110, with the wireless card being Intel 3945 ABG.

The process involves installing Intel wireless driver iwl3945, Intel iwl3945-firmware, and enabling NetworkManager daemon to use it.

CentOS 5.3 or newer (ie, kernel 2.6.18-128 or newer) includes Intel iwl3945 driver by default. If you have an older version do a system update.

Some modern laptops require firmware to make the wireless network connection work on CentOS. The main reason for this is that wireless device manufacturers do not allow the free redistribution of the firmware that is required to make the device work.
Intel-firmware is available in RPMforge repository and not in default CentOS repositories. If you have not added RPMforge, do it now by installing yum-priorities and RPMforge as detailed in the below two steps.

Install yum-priorities, enable it and setup priorities by following the steps here. Yum priorities is required to prevent package conflicts between CentOS and third party repositories like RPMforge.

Install RPMforge by following these step. Make sure you have done everything correctly.

Then, install the intel wireless firmware by
yum install iwl3945-firmware

Reload the iwl3945 module:
rmmod iwl3945; modprobe iwl3945

Start the NetworkManager.
service NetworkManager start

Now the NetworkManager icon should be shown in the system notification area. Clicking on this icon, should list your wireless network (It may not be shown if you have SSID broadcast disabled in your router).
If it is not listed, there are options to  ‘Create a new network’ or ‘Connect to a hidden network‘ in case you have SSID broadcast disabled. You can specify your security settings like WPA/WPA2/WEP etc and other settings like DHCP/StaticIP here. Remember to add DNS info here.
[Please note that you do not need to try using iwconfig, ifup, wpa_supplicant etc etc. NetworkManager will handle all that.]

If things go fine, configure your CentOS system to automatically start the NetworkManager on startup.
chkconfig NetworkManager on

I was able to use WPA2 AES with SSID broadcast disabled.

The wireless LED remain off always. This led me into some troubles initially as i thought things were not working.
That’s all in it!

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Some of the error’s I got,

“SIOCSIFFLAGS: No such file or directory Linux…”
I got this error message whenever i tried ‘ifup wlan0′ ‘iwconfig’ etc. In my case it was because the firmware was not installed. Once the firmware was installed it disappeared. In CentOS you can test whether the firmware is installed successfully by
ls /lib/firmware
This should list a file with name something like iwlwifi-3945-1.ucode

NetworkManager keeps on asking for keyring unlock password. This can be solved by exactly following the steps outlined here.

If i do a iwconfig i get the following error,
“Warning: Driver for device wlan0 recommend version 21 of Wireless Extension,
but has been compiled with version 20, therefore some driver features
may not be available…”
Still have not found out why this happens and how to solve this..

==================================

Sources:
CentOS wiki on laptop wireless – http://wiki.centos.org/HowTos/Laptops/Wireless

Gnome saved-sessions may not work well with Compiz.

When i saved a session and when i tested it after logging out and in, the screen was black with only mouse pointer displayed. After 2-3 minutes the session [windows] that i saved were displayed but all windows were without title-bars, and also without borders. There was also problem with the menu and panels. The windows can be bought back to shape by disabling Compiz [from System>Preferences>Desktop Effects].

But I wanted to delete this saved session and make things as they were after installation.

The trick is to delete the session file in the ~/.gnome2. Or to be safer try renaming it to something else.


cd .gnome2
mv session oldsession

Logout and in to see the results.

Why CentOS?
I want an enterprise class linux that is free. Having used RedHat and Fedora earlier, I prefer a distro from the same league. CentOS is bit by bit RHEL that is built from the free RHEL source code [with its branding and artwork removed]. I also want to install VMWare, and CentOS is is supported by them.

My Hardware,
Wipro Little Genious laptop, Model WLG7110.
Intel Celeron M CPU 430 @ 1.73GHz , 1.5 GB RAM, 80GB Fujitsu HDD, 1280×800 wide screen display, Syntek 1.3MP webcam, Intel Pro 3945 wireless, Realtek RTL 8139 NIC, bluetooth, Ricoh 5 in 1 card reader, TSSTCORP CD/DVD RW, Intel ICH7 soundcard etc

Downloaded the CentOS 5.2 DVD .iso using bit-torrent with Vuze.

I already have WinXP installed. So deleted a partition at the end to create a 15GB space.
Just glanced through the Installation guide and thats when i learned about Logical Volume Managements (LVM). Decided to use LVM’s this time. LVM can be resized, moved to another harddisk etc without affecting the OS installed or data residing in it.

I always use the hard drive installation as i am too lazy to burn CD’s.

We need a boot CD or USB to begin the installation program from harddisk. Created a boot USB from the diskboot.img file provided in the .iso using using the dd utility in an another linux system.
dd if=diskboot.img of=/dev/sdb

Reboot and started the installation program from USB.

Chose linux askmethod to use harddrive installation medium and specified the partition containing .iso [/dev/sda5]

Next comes partitioning, this is where we create LVMs
Created a /boot of 100mb type ext3
Created a Volume Group CentOsVG
Created two Logical Volumes, SwapLV 2GB for swap
and RootLV 13GB type ext3 for /

Grub to MBR

Installation done and when i rebooted to the new system, there were a few problems, sound was not properly working [gets muted randomly] and wireless card was not even detected.

Decided to do an update before trying anything to fix them. Setup a wired network and did a system update using yum
yum update

Yum showed 508mb to download and the whole update took 5hrs in my 256kbits/sec line.

Now i have CentOS 5.3 the latest version. This can be checked it by the command
rpm -q centos-release

Sound is perfect after that.

Wireless card is detected but still cant connect. Followed the steps at CentOS wireless how-to wiki to install card’s firmware and enable NetworkManager to use it. There were a problem with NetworkManager asking for keyring password every time, but the solution to it was also in the same wiki.
I was able to use wireless with WPA2 AES with SSID broadcast disabled. More details can be found here.

To Do:
Check the webcam.
Check the card reader. (it is detected)
Check IEEE 1394 port(Firewire)