no need to watch data packets for specific ports and data sizes live while its being sent.
afterall ISP's are keeping metadata for years on every user(yea we know they keep more then just metadata, but shhh)
meta data is easy..
search keywords: "useragent satoshi"
search keywords: "useragent bitcoin"
Do you think ISPs could start ratting out Bitcoin users to the government? The government could force them to get on board with that easily. ISPs can blacklist all the unlicensed gambling sites in countries where gambling is regulated or forbidden so ISPs could be the ultimate watch dog to keep track on this lucrative Bitcoin business.
I wonder if they are keeping tabs on Bitcoiners with a lot of coins using web wallets. Do you know what they keep on users aside from the metadata you mentioned? Like passwords and search patters or more? Or passwords are encrypted and they can't get their grubby fingers on them?
knowing who uses bitcoin is super easy, they know all your cookie data.
so even if you use blockchain.info or an exchange as a webwallet.... they know!
they can 'clone' a session with a webservice and look into what you are doing by just emulating the data that goes between you and the website.
so finding how much you have 'online' is easy.
its a little harder to know how much funds you have stored privately (desktop wallet/paper wallet) but just knowing you use bitcoin is a millisecond search for keywords.
though bitcoin is not illegal and so there is no reason/point to care right now.. however KNOWING the weaknesses to prepare for 'possible' future changes is atleast worth it, just to not be shocked if things do change.
also ISP's keep logs for YEARS. so lets say laws change in 5-10 years, they can retrospectively look back and highlight people.
afterall its only 5400 nodes, spread out over 200 counties. so america only has to be concerned with 1500 people, UK under 400 people. so it is easy to manage for them. they are not having to worry about manually searching millions.. just hundreds/thousands. which take milliseconds to find
atmost its less than 1000 people found in only a couple milliseconds per ISP or atmost 1500 per country.
but right now governments are not caring about arresting people for just running bitcoin. so dont be concerned for knocks at the door today. but do be aware what you do now could end up as a red flag if a future law is implemented and they retrospectively look back through logs and then put on a fture watchlist.