To be clear, it doesn't work today because OS's reacted to neutralize the possibility. At this point there is so much "Internet Background Radiation" of consta

To be clear, it doesn't work today because OS's reacted to neutralize the possibility. At this point there is so much "Internet Background Radiation" of constant port scanning and everyone has just accepted that you are being constantly scanned by, say, Shodan and it's ilk that this threat doesn't seem super-alarming. Back in the 1990's- when SSL wasn't everywhere, and telnet was still a thing- someone who could silently find your attempt at security-through-obscurity 'I moved telnet to port 2525" nonsense that was still done pretty regularly in 1998- was a big deal.