The Deliverator – Wannabee

So open minded, my thoughts fell out…

More Fun with Fon

Posted by Deliverator on March 22nd, 2007

I had some more fun with my La Fonera this week. As in my last post, from hence forth the La Fonera shall be simply known as the lwb. The week started off with my lwb in a bricked condition thanks to an attempt to flash a new daily build of dd-wrt onto the device using the web interface over a wireless connection. Thankfully, I was able to still access Redboot after bricking my lwb and was able to flash to the version of dd-wrt from 0319. I heartily recommend that once you get your lwb up and running with dd-wrt, that you use ssh to flash to future version and not the web interface.

You can flash to the latest version via ssh by doing the following:

cd /tmp
wget <newest version of root.fs>
wget <newest version of vmlinux.bin.l7>
mtd write vmlinux.bin.l7 vmlinux.bin.l7
mtd write root.fs rootfs
reboot

Anyways, once I had my lwb unbricked, I was eager to try a rather neat feature present in 0319, the ability for the lwb to act as both a client to a wireless network as well as act as a wireless router….at the same time. Pretty neat trick for a device that only has one radio, eh? The lwb is capable of doing this juggling act thanks to its Atheros radio. I recommend upgrading to 0319, as this feature has been broken in many of the recent daily builds. Supposedly, the build from 0310 will work as well.

So, why would one want to do this? For one, it allows one to create a “repeater” for an arbitrary wireless network which may not quite reach to where you want its signal. It does it in a way which is compatible with security systems like WPA, unlike WDS repeating, which requires special set up and has a number of undesirable technical limitations. With the lwb, it is possible to create multiple virtual ap’s and create different rule sets for each.

I tested this single radio repeating at Hacknight this week, connecting as a client to the the internet cafe’s wireless network with the lwb acting as a wireless access point with routing as well. In this mode, the wired port on the lwb which is ordinarily used for wan connectivity acts as routed port, enabling wired devices to join in the fun. One can also put the lwb into a bridging-client mode, where the lwb acts as a wireless client and transparently passes traffic to the wired interface, but I haven’t tested this yet. This can be useful for connecting NAS appliances, network printers and other conventionally wired devices to your network, without any real limitation as to where you can place them. Don’t have enough room in your office? Put the printer in the linen closet! Wireless bridges really let one unclutter one’s environment.

I did one little last bit of hacking on my lwb this week. Erik Butler commented on a video he’d seen on YouTube in which the plastic casing of the lwb had melted due to the heat. The lwb is a *little* white box and doesn’t have almost any ventilation. A number of users on Fon’s own forums have commented that their units seem to be overheating and spontaneously rebooting as a result. At least two people have explored this issue in a pseudo-scientific like manner. The general conclusion seems to be that the ventilation in the lwb is woefully inadequate and that the high temperatures are likely to result in a drastically decreased operating lifetime, with the likely cause of death being capacitor failure. I have definitely noticed that my lwb runs quite hot, so decided to protect my investment of 0$ by adding a fan to the unit. I managed to scrounge a fan from an old motherboard chipset cooler which was of an appropriate size and voltage rating and with the help of my soldering iron and dremel tool, was able to add it to the lwb. My lwb now runs MUCH cooler, with no appreciable heat build up.