if governments can detect even the passive reception of signals (http://www.bbc.co.uk/pressoffice/pressreleases/stories/2003/...), I don't think it would be too difficult to pick up who is talking to these devices. Or, even if they can't, fear of detection would probably keep a large chunk of the populace compliant.
Which isn't to say that such devices wouldn't be useful. Just that they'd be far more effective in situations like Egypt or Libya than in ones like Iran or China. I think they'd be even more useful in the hands of someone like the Red Cross.
I am not a physicist, but that's detecting reception of (I think FM) UHF and requires specialised equipment. Detecting Wifi which uses a spread-spectrum modulation at a higher frequency would be even more difficult. Add to that the existing, allowed Wifi networks that probably already exist which overlap the banned ones.
The real problem in security is usually human factors — loose talk, spies, informers, interrogation — not technological ones.
But the thing is that using a wifi node is not passive reception. And while wifi uses spread spectrum, in order to be accessible to the people you want to reach, you'd need to make it available using common protocols. The authorities need only go war driving for these nodes, connect and then watch the tcpdump output. Corporations do this now to detect rogue access points, so I don't think it's beyond the means of a sufficiently motivated government.
'TV detector' vans are basically myths used to enforce licence paying. They've now moved to a 'the database knows!!!' way of scaring people and don't talk about TV detector vans any more.
Comments
if governments can detect even the passive reception of signals (http://www.bbc.co.uk/pressoffice/pressreleases/stories/2003/...), I don't think it would be too difficult to pick up who is talking to these devices. Or, even if they can't, fear of detection would probably keep a large chunk of the populace compliant.
Which isn't to say that such devices wouldn't be useful. Just that they'd be far more effective in situations like Egypt or Libya than in ones like Iran or China. I think they'd be even more useful in the hands of someone like the Red Cross.
I am not a physicist, but that's detecting reception of (I think FM) UHF and requires specialised equipment. Detecting Wifi which uses a spread-spectrum modulation at a higher frequency would be even more difficult. Add to that the existing, allowed Wifi networks that probably already exist which overlap the banned ones.
The real problem in security is usually human factors — loose talk, spies, informers, interrogation — not technological ones.
But the thing is that using a wifi node is not passive reception. And while wifi uses spread spectrum, in order to be accessible to the people you want to reach, you'd need to make it available using common protocols. The authorities need only go war driving for these nodes, connect and then watch the tcpdump output. Corporations do this now to detect rogue access points, so I don't think it's beyond the means of a sufficiently motivated government.
'TV detector' vans are basically myths used to enforce licence paying. They've now moved to a 'the database knows!!!' way of scaring people and don't talk about TV detector vans any more.