Broadcom wireless cards are tricky to set up in ubuntu, and the forums are full of frustrated users seeking advice. Broadcom provide no Linux support (feel free to complain to your hardware vendor or choose a different card if you haven't yet shelled out your cash), but they can be made to work - and you're in the right place if you want to know how.
First, you need to find out if this How To is for you. Broadcom wireless cards come under many brand names and, in particular, are used in many Dell and Acer laptops. Look for the drivers supplied with your card (Dell usually store a copy in C:/DRIVERS/NETWORK/ADDON); if you have a file called bcmwl5.inf or bcmwl5a.inf then keep on reading. You won't succeed without following these instructions!
0. Before you start, clear out any mess from existing failed attempts to use ndiswrapper.
sudo modprobe -r bcmwl5 sudo rmmod ndiswrapper sudo apt-get remove ndiswrapper-utils sudo rm -r /etc/ndiswrapper/ sudo rm -r /etc/modprobe.d/ndiswrapper
Some of these steps may report errors; just ignore them.
1. Copy the bcmwl5.inf and bcmwl5.sys files to your desktop
2. Follow the advice given here under How to add extra repositories
3. Open a terminal session and enter this code. Note that you need an active network connection for this to work; I've assumed that if you have access to a wireless LAN, you also have access to a wired network as a fallback.
sudo apt-get install ndiswrapper-utils sudo ndiswrapper -i ~/Desktop/bcmwl5.inf sudo ndiswrapper -m for conffile in /etc/ndiswrapper/bcmwl5/*.conf; do sudo cat $conffile | sed -e 's/RadioState|1/RadioState|0/' > $conffile done
4. Reboot your PC. On restarting, the light on your wireless card should come on. If not, try entering
sudo modprobe ndiswrapper
5. Your card is now working. Open the networking configuration tool System --> Administration --> Networking
6. Select your wireless network card (probably wlan0) and hit the properties button.
7. Tick the 'This device is configured' box, and enter your network name and connection settings. Ask your office network administrator for support if you don't know what this question means, or copy your settings from Windows.
8. BE CAREFUL entering your WEP key, if you're using one. You're expected to enter this in hexadecimal form; if you don't speak hex, prefix your key with s:
9. Click OK. The screen should close fairly quickly; if it hangs, you probably aren't connected properly.
10. Back in the Network Settings screen, select your wireless device as the default gateway device.
11. Click OK. Again, the screen should close fairly quickly.
12. Enjoy wireless nirvana. If everything works, you can delete the file from your desktop.
13. You might notice that the signal strength applet doesn't work properly. This is a known bug with these cards.
If you have trouble, try booting into Windows - if you dual boot - and checking that the card is enabled. Some laptops allow the wireless card to be switched off, usually with a special key combination, and I've not found a reliable way to make this work in Linux.
(Note: This how-to has been updated to reflect all comments from the thread up to 19 April)
Lenovo E290-420[Celeron-M420/256M/60G/Intel GMA950]