Thursday, December 1, 2011

Turn an Ubuntu Linux box a WAP (Wifi Access Point)

I recently helped a friend of mine James Miller setup an Ubuntu Linux box as a wireless access point. I had never done this before, but I found it to be pretty straightforward. Here is the very abbreviated version of the things that need to be done assuming that your wireless driver is supported by the nl80211 interface in the Linux kernel:
  1. Install hostapd
  2. Add a configuration file for hostapd
  3. Modify /etc/network/interfaces to bring up the hostapd config
James and I used an ath5k card to pull this off.

Installing hostapd:
At a root prompt, type: "apt-get install hostapd". Doing so will install all the machinery needed to bring up a WAP, but it will have no configuration.

Creating the config file for hostapd:
In /etc/hostapd/{essid}.conf, use the following contents for an unencrypted WAP:
ssid={essid} channel=1 # may want to replace with another channel
Of course, you should replace "{essid}" with your actual essid.

Modifying the /etc/network/interfaces file:
You'll need something similar to the following:
auto wlan0
iface wlan0 inet static
  hostapd /etc/hostapd/{essid}.conf

That should get you a simple unencrypted WAP setup. If you want encryption, you can use hostapd to implement simple WPA2 personal or more interesting WPA2 enterprise style security (among other options). I would strongly recommend at least WPA2 personal (a.k.a. pre-shared key or PSK) encryption unless you have reasons to make it less secure.

Note also that this setup will leave you with your wireless network and other networks on separate layer 2 domains, which means that packets will need to be routed between them. You'll probably also want to get dhcp running so that you don't have to manually configure clients on the wireless network. I am going to leave getting these additional bits working as a exercise for the reader. As a hint, checkout the isc-dhcp-server package and the net.ipv4.forward (for IPv4). You might also want to check out the shorewall package as a nice firewall. :)

Good luck!

Tuesday, March 8, 2011

Samsung SCX-4623FW Supported by Fully Open Drivers

I was searching for a new smaller printer/scanner recently. I don't print out much, so I wanted a black-and-white laser printer. I also wanted a scanner so that I can get rid of my old printer/scanner since it's so big.

Finding a new printer that is supported by open drivers is really difficult, and configuring SANE backends is not my definition sanity. However, I looked on the SANE database and found that Samsung's SCX-4623 is supported. I couldn't find any support in the Linux Foundation's OpenPrinting database for the SCX-4623. So...I took a leap of faith and bought the printer for about $150.

To be clear, many vendors, including Samsung, offer binary drivers for their printers. However, I really wanted to use the open drivers so that I could contribute to the systems involved instead of being locked out.

The first step was to get the scanner working. At first, I tried to get the xerox_mfp backend working. I just added the following line into the /etc/sane.d/xerox_mfp.conf config file: "usb 0x04e8 0x3440". This did not work as the SANE backend did not seeing the scanner. After a significant troubleshooting effort, I found that the SANE backend had a bug that prevented USB scanners from being used with the xerox_mfp backend. I have reported the bug and presented a patch to the SANE community. See it here. After applying this patch, I was able to successfully scan at 1200dpi in color. That's full capacity for this machine. Success is mine!

This machine also supports ethernet and wireless. Both worked for scanning after configuring the xerox_mfp backend with the machine's network address and port. The same bug didn't affect the networked support for the xerox_mfp backend, so everything just worked.

Great, so the scanner works, now what?

So, now I had to get the printer working. The printer supports the ipp protocol. I was hoping that I could just use some generic CUPS filter to work with it. The printer claimed support for PCL5e in the web interface for the printer, so I just used the generic PCL5e driver and the ipp address of the printer. Everything just worked!

My next step is to write a PPD to properly describe this printer fully. I am also trying to figure out out to get this info integrated into the OpenPrinting database.

Having said all this, my printer/scanner is running totally on free and open source software, and I can recommend this to others looking for a printer that's fully supported by free and open source software.

I would also like to reach out to Samsung and encourage them to let their users know this information so that their users don't have to go through the hassle of installing binary only drivers that only work on x86_64 or i386 architectures.

This information probably also applies to the SCX-4623F, which doesn't have wireless support.