Building an embedded linux Radius appliance - Part 1
November 3rd, 2005
Linux 
Administrator
I decided to begin doing research on a project that I have been milling over in my head for nearly a year now. The concept was simple enough: With WiFi hotspots as prominent as they are now, their popularity will certainly rise along with the need for WiFi hotspot owners to control access.
One of the first steps I decided was necessary was whether prefab hardware was available to provide a small footprint. There’s no sense creating an appliance that has an ATX motherboard with dual NICs running Linux - that’s a computer. I wanted a sleek, slim, to the point appliance that a cafe owner could plug in and go - not a big bulky somputer generating more noise and heat.
What, you may ask is a Radius server? A radius server is an authentication server ensuring that a user name and password matchup. The radius server also stores various options such as time limits, bandwidth limits, etc. that it can pass back to other services after authentication. Authentication is achieved through a standard user name and password (CHAP), or more advanced methods of authentication such as EAP.
Why would cafe owners possibly be interested in something like this? Imagine you offer free wireless at your cafe. Within a few months of opening you are pleased to see your shop is filled to the brim (no pun intended). However, for as busy as you seem — the profits are not there. What’s going on? Simple - leechers. People will sit themselves down, spread out on a table, pull out the laptop and a cell phone and basically use your cafe as a “portable” office for siz hours a day.
How would this Radius device work within the confines of the cafe? After a purchase of an item - a coffee, a bagel, or whatever - the receipt number would be entered into the system by an employee valid for “X” hours. The customer takes his/her receipt back to their table, powers on their laptop and enters the receipt number into the web page that appears.
After a bit of searching, I found the perfect device that even has two Mini-PCI slots at http://www.mini-box.com/s.nl/sc.8/category.19/it.A/id.281/.f. The site even sells cases designed around the footprint of the board as well as the necessary power adapters. All-in-all, a cool $180 will suffice. Because the motherbaord has no IDE connections, I will have to delve into embedded linux land using a Compact Flash card.
I came up with the following outline for this project:
- Small footprint - 256MB to 512MB
- Bootable without need for configuration - “Plug & Play”
- Custom configuration can achieved through a user friendly web interface
- Strong Firewall options
While I wait for the ordered WRAP.1E board to arrive, I will build a prototype machine to test the functionality of the software.
See you in a few days!
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