From an item in The Guardian last year, 'A “computer network expert” told the Telegraph that the Beeb might be deploying a modified version of a tactic known as “packet sniffing”, which looks at the nature of data passing through Wi-Fi networks without actually intercepting it. The expert claimed that iPlayer data could be modified to make it distinguishable from other traffic without actually looking at its contents.
The BBC issued a statement rebutting the Telegraph article (without naming it), saying that there had been “considerable inaccurate reporting this weekend about how TV Licensing will detect people breaking the law by watching BBC iPlayer without a licence”.
“While we don’t discuss the details of how detection works for obvious reasons, it is wrong to suggest that our technology involves capturing data from private Wi-Fi networks."
However, carrying out the sort of mass surveillance suggested by the Telegraph is likely to be prohibitively expensive, technically challenging and quite possibly illegal.'
'Besides, there are other ways for the BBC to tell who is watching without paying. It has ruled out combing its own records of computers that have logged in to iPlayer and matching those up to licences, but it is authorised to use anti-terror legislation – the Regulation of Investigatory Powers Act – to target people it already suspects of watching without a licence. It could, in theory, use that authorisation to access internet records of which sites you have visited. Even if surveillance vans were used, a targeted approach and one that didn’t monitor Wi-Fi traffic, would make more sense.'