Building an embedded linux Radius appliance – Part 2

Choosing the right distro for a custom embedded Linux system is not easy. Most distros will not even install the most basic elements of the operating system in less than 512MB of space.

To begin the second phase of this project, I decided to partition an old hard drive to only 512MB – just to see if I could get a fully functional Linux system with Apache, PHP, and of course MySQL. FreeBSD 5.4 was my first choice of OS. After I kept receiving Singal 11 errors due to the fact that the install needed more than 512MB of hard drive space, I quickly moved on to explore pre-built LiveCD images designed to be installed to hard disc, Compact Flash, or a USB thumbdrive.

I was immediately surprised to see the number of projects available for embedded systems – however, since I did not even have my WRAP.1E motherboard and the compact flash card yet, I put these ideas on ice. One very noteworthy mention though is the m0n0wall project. m0n0wall can be installed on a CF or is available as a bootable LiveCD and provides advanced routing & firewall protection with an extremely well designed Web GUI configuration front end. By inserting a floppy into the machine, you can save your preferences for later retrieval. I decided to model the level of configuration and clean looking configuration GUI after this distro.

After other disappointed attempts at installing pre-made images for embedded systems, I moved onto a distro I rarely think about anymore: Slackware. Slackware is a great distro for advanced users who need a slim and trim install. There’s no fluff with Slackware. In fact, by choosing only the most basic setup options in the installer, I was able to get my install working on just 125MB of of hard drive space. This install included Apache and PHP.

To get your own pre-image / prototype working, format a hard drive to just 512MB (preferably the first partition). Download and burn just the first Slackware CD. Slackware does not have ISO images available directly from their website or mirrors, however, you can get the ISO using BitTorrent at slackware.com/torrent. Boot the CD and install only these package groups:

A, AP, L, and N

Be sure to choose the Expert mode install so you can also select the individual packages. Uncheck everything that is unnecessary, i.e. audio, graphics, X support, gcc, etc. and check those packages we do want, i.e. Apache (with mod_ssl), PHP, MySQL, OpenSSL, etc.

After installation and boot up, it took a few more rounds of installing necessary libraries. You can easily install needed libraries by mounting the Slackware install CD and changing to the the directory /mnt/cdrom/slackware/l (assuming your CD is mounted under /mnt/cdrom). Then type pkgtool and select Current directory. It will then list each and every package in the directory and prompt you with Yes / No / Cancel. In my install, I needed some extra libraries to get PHP and MySQL working properly.

Once you get all the necessary packages installed and configured, spend some time ensuring everything works. Check that your network interfaces are up and properly configured and that after a reboot, all daemons are started. Remember, we want a system that is bootable and does not require logging in to a console to start or configure.

See you in a few days!