Gallery

WLANs: liberators or liabilities?

Posted on 16 Jun 2009 at 00:00

A visit to his accountant leads Steve Cassidy to spout the pros and cons of wireless technology.

I rather enjoy visiting my accountants - they have a nice office, their coffee is good, and during my last visit I had the pleasure of wishing my main contact there a happy retirement. As a result of this event, I was required to present a potted introduction to the strange world of Cassidy to the new team, along with a small parcel of free advice. The free advice tends to follow naturally after such an intro, whether from a sense of incredulity over some over-blown claim to fame, or because someone has a pressing problem occupying their mind, and on this occasion it stemmed from a cautious conversation about wireless networks.

This wasn't the usual, namely a single, pointed question like the classic "What do you reckon about the BT Home Hub? Is it as secure as they say?" (Just for the record, what "they" say is that the connection is secure, in the sense that it's more reliable than that of their competitors, but they claim nothing about the security of the traffic over that connection.) No, this time it was a more general enquiry about what attitude I take toward the whole matter of wireless technology. So I told them... Now I'm quite used to watching people put on their poker face during my advice sessions - it happens a lot because they've all watched The Apprentice and think that's how you're supposed to act. (By contrast, when they watched Susan Boyle perform on YouTube they thought Simon Cowell's reaction was too obvious, and that he didn't play his cards close enough to his chest.) The way I see it, is that the stiller you sit, and the calmer you try to appear while waiting for the punch line, the more detectable your tiny reaction will be when it arrives. I summed up my attitude to WLANs roughly thus - that I'd never transact any business of any description across one, ever, ever, and that's why I have credit cards, eBay and PayPal accounts, while my brother (a keen wireless LAN user) doesn't. Their faces froze into Noh masks, which meant that I'd just touched some sort of nerve.

It turns out, to cut a long but amusing story short, that these chaps were somewhat short of office space and had hence rented an annexe. I use that term deliberately: it was a suite of offices not directly connected to their main building, and their link between this annexe and the main building is a point-to-point wireless LAN bridge. We had a roundabout sort of discussion, never directly addressing this as the principal topic. "How hard is it to crack a wireless signal?", they asked. The answer is that a log of an encrypted WLAN session can be uploaded to a botnet and cracked within a matter of hours. Then they wanted to know how much signal overspill there is from their annexe point-to-point link? I stopped at this one because they're in the centre of London, an area where "overspill" pretty much defines the entire wireless LAN experience, with anything up to a dozen WLANs all overlapping madly with one another just about everywhere you go.

Yet their point-to-point link was happily performing very much like a cable, except when it got windy, someone added. This last casual aside gave me my get-out clause. If their point-to-point link is failing, the instant its two transmit/receive units become even slightly out of alignment, that means it's so exquisitely directional that, short of someone clambering over the intervening rooftops clutching a laptop, that particular wireless link was going to be far better than average in terms of secure communication. Now I don't enjoy gleefully pointing out the shortcomings of a technology as popular as wireless without offering some constructive advice too, as a sort of antacid. So whenever I'm obliged to capitulate and recommend wireless kit to be attached to someone's business network, I like to suggest something robust.

Download a year of Steve Cassidy's Networks columns by heading to our Free Downloads site