The good news is, it is possible to get the Netgear WNA 3100 N-300 Wireless Adapter to work in Linux (at least in anything Ubuntu-based, but the method below should work with most distros), but the bad news is that it’s not exactly a walk in the park to get there. I have put together a quick tutorial here on how to get the adapter recognised and running on my 64-bit Linux Mint 13, with the help from various online sources, forum messages and technical support pages.
First up, under the hood the WNA3100 is a Broadcom 43231 device, which you can see when you type lsusb on the command line (if your system recognizes it, which it should). As far as I can see, any distro-based driver files, like the STA Broadcom packages that are available in the repositories, do not work with this device. So to make this work, we need software called Ndiswrapper, to be able to use the original Windows driver in Linux. Install Ndiswrapper from the repositories, it doesn’t matter which version, as long as it’s a fairly recent one. Then, as I learned on this site, we need to have a package called bcmwl-kernel-source deinstalled via the Synaptic packet manager, and also make sure that the packages b43-fwcutter and firmware-b43-installer are there. Then, sudo gedit on the command line, open /etc/modules.d/blacklist.conf, and check that there is no entry “blacklist bcm43xx”. If there is, put a # in front of it.
With this you should be all good to go. Now, my problem was that the drivers that were suggested in the forums, the bcmwl5.inf for 32-bit, and bcmwl6.inf for 64-bit, did not work on my machine, when I tried to install them with ndiswrapper it gave me an error message that this was the wrong driver file (I suggest you install any driver on the command line via sudo ndiswrapper -i, and check if your device is then working or present via ndiswrapper -l, that way you get to see any error messages, as opposed to when using the graphical ndiswrapper frontend ndisgtk). So I eventually found the right driver here via this website, and that one installed flawlessly, and after reboot the WNA3100 was recognized and working, the wireless network was there, and now Bob’s your uncle. Hope this helps.
Update : Of course, if you just want a working USB Wireless adapter that does plug-and-play and doesn’t take a week to get to work, you could just buy the TP-Link WN822N adapter for 30 bucks. Which, as I will happily admit, I did today, after consulting this Ubuntu Wireless compatibility website.