Tuesday, June 16, 2009

Poor man's wireless

I am not cheap, I am just a student. You know, here in Switzerland, Internet costs a lot: you've to pay your "link" (phone or TV - 20$/month), then the connexion is damn expensive for a single guy (50$/month). Moreover, it is well known that when you are a student, you have no money.

Thus, I decided to borrow my neigbourgs wireless connexion. Ok, I agree, nothing new here. We will say for the purpose of this article that an open connexion means a connexion that is "shareable" and we will only be interested in them.

When I got my first laptop, I was always scanning around trying to find wireless. It was not very conclusive, or sometimes I got such a poor quality signal that it was impossible to connect. Piano piano, I was looking toward a solution to increase this signal strength. When you speak about signal gain, you cannot think about not using an antenna. Good, that was my starting point: getting an antenna. However, few questions arised:
  • Which antenna ?
  • How to connect it with the computer ?
  • How much does it cost ?
At that time, wireless hardware was more expensive that today, and difficult to find a dealer that accepts to ship to Switzerland... Anyway, I heard that an omnidirectional antenna is not that bad. I knew what an omnidirectional antenna was, well, at least more or less. Usually this is the kind of antenna you can see everywhere.

Omnidirectional antenna

At that time, I found a wifi-card on eBay: Senao 802.11b, 200mW with a mmcx connector. Actually, I was looking for a powerful card (I had the idea "the more powerful the best"), but also for a card accepting injection, and this criterion narrowed down the panel of wireless cards to 3 or 4 cards. This one was right in my budget !

My first PCMCIA card

When I received it, I was so happy to discover there were tens of network in my neigbourhood ! Moreover, lot of them were open :) (which is no more the case toay :( ). I was happy with this solution, with my Senao pcmcia card and my omnidirectional antenna. Obviously I was happy for few days, but after a while, I wanted more: how can I have a bigger signal strength, less noise, higher bitrate and a reliable connexion ? After studying all types of antennas, I figured out that a parabolic antenna was the top choice for my use (we will see why maybe later on). I finally ordered a 20.5dbi parabolic dish somewhere in France. So now, I still had my pcmcia card, with a big coax cable going on the parabolic antenna.

When I bought the Senao, I did not really take into account the fact that the card was only 802.11b compatible: how can you connect to a network that accepts only 802.11g ? Even worse, how can you sniff/jam/inject/replay (whatever) packets if you are not able to intercept them ? Raaaa, it was a mistake ! I decided to sell my Senao to buy another one, supporting 802.11g. I wanted a card fulfilling the following criterion:
  • Atheros based chipset
  • Powerfull
  • External antenna connectors
Once again, it was not very easy to find. I finally bought the PCMCIA ubiquity SMC (SuperRangeExpress) 300mW, 802.11a/b/g with an MMCX connector. This card has pretty good performances, despite the fact you cannot use it without an external antenna. I could really feel the difference between the two cards, both in term of speed and reliability.

Now that I was fully armed, with my parabolic dish, I was able to connect to any network in range.

It was great, until I started to live with my girlfriend: she also wanted an internet access with her laptop and I definitely still didn't want to pay for internet when you can get it "for free". Now, I was facing a new problem: how can I provide internet to my girlfriend, too ?
  • Connect my laptop to the antenna, as usual, and setting my laptop as an access point. This might work, but what if my computer is turned off ?
  • Finding a was to efficiently repeat my neigborh's signal without the need of a computer in between. Huh, actually this device already exists and is called a "repeater".
I couldn't afford to buy a repeater, there were damn expensive, actually they still are. After some hours of google search, I figured out that a firmware called dd-wrt had a sort of "repeater" mode. Actually, it was totally unstable, but this was exactly what I was looking for. Moreover, at my parent's house I already had a linksys wrt54g, so I immediately flashed it. It was working pretty well, with a nice graphical interface. I decided to buy another one for my girlfriend and I. That was it, we had this linksys router on my balcony, attached to the parabolic dish and it was working damn well :). In a nutshell, we are repeating an unencrypted signal and set a new encrypted virtual network -> that's a bit paradoxical.
Then, I figured out that the buffalo whr-hp-g54 was more powerful (it got an amplifier), nicer, smaller and about half the price of the linksys one (~50$).
Buffalo whr-hp-g54

This was a pretty good choice actually and I am still using it. It has been resisting weather constraints for more than 3 years without any failure, it's just impressive. However, I confess that sometimes it's not working totally properly: for some reasons the bitrate is extremely slow.

So why "poor man's wireless" ? That's simple: router + antenna + connectors = 100$ which are around 1month and a half of internet.

Now that we have all the material, the fun can begin !

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