What is so great about OpenWRT?
Lately I’ve been experimenting with OpenWRT, a linux distribution for embedded devices. The great thing about OpenWRT is that you can install it to most of the cheapest WLAN devices, ie. routers (check the table of supported hardware).
I know that most Open Source projects may never be as good as proprietary solutions for real implementations. However, in the particular case of OpenWRT, I have identified three major advantages:
It’s a great tool for research
It’s an awesome tool for researching on many fields such as: protocol design, fast handoff schemes research, WIDS, Wireless mesh networking, and so on. Learning and doing Unix socket programming in C for OpenWRT may give a large number of headaches, but it’s the best way to get the full control of the information sent over the air.
It’s a great study tool
There’s indeed a difference between reading about the 802.11 standard and getting hands-on training equipment -of course, reading is extremely important- but some of the most advanced concepts are not available anywhere but in enterprise solutions. If you don’t have the access to such equipment, you may want to install OpenWRT on your (cheap) Linksys WRT54GL and also install some packages that would do the magic.
For instance, how do you see what is actually going on through a WPA2-Enterprise (with a RADIUS server, EAP/MD5 auth) handshake on both the wired and wireless side? You could install FreeRadius to a linux box to use as authentication server. Sniffing the air is possible by using wireshark or tcpdump in the OpenWRT box.
If you want to learn a little more about WLAN Controllers, you may want to take a look at the ChilliSpot project. You need to install it on both a WRT54G and a Linux box to see it in action.
VLAN segmentation by editing configuration files, deploying a VPN server on the router, wireless mesh networking using different routing protocols, installing Asterisk on the box, etc. There’re A LOT of packages that can be installed.
It’s as simple as this: you get many of the features only found in (expensive) enterprise solutions by installing a free firmware on a $60 router.
As I said (somewhere) above, OpenWRT may not be suitable for large enterprise implementations (should not), but it’s a great tool for studying the 802.11 standard, researching or just having some fun. I do not recommend it for illegal purposes.
The idea of writing this post came up after reading a question asked by @jameyk1stner via Twitter which basically stated: is there any way to practice for the CWNA exam with real scenarios by using real APs, Controllers, etc?.