Подскажите, какая методика защиты от фейковых ntp-серверов является основной?
Допустим, хакер Джон решил сменить время на каком-то из ntp-серверов. А у меня их указано 2 или 3.
Как производится процедура голосования при выборе правильного времени?
В инете нашёл такое мнение: «However, from my experience stratum level is not always the winning factor in primary source election. I think latency and jitter have significant influence as well. I had noticed on several occasions that lower stratum server was elected as primary source even though there were several higher stratum servers available only because it had the lowest latency. That is why I cannot guaranty that suggested approach will work.», URL (NTP fudge network source stratum)
Также, следующие советы от 2014-2015 годов: «ntpd reference implementation with External Clock Discipline and the Local Clock Driver (Complicated): This is still a solution that relies on using the ntpd reference implementation but I am not very familiar with it. All I can do is give you the link to more details: http://www.eecis.udel.edu/~mills/ntp/html/extern.html (2014)
Jans - third party ntp testing tool. I have no experience with this product but I know of it from the ntp mailing list. It will allow you to server faketime but it does none of the clock discipline like the reference implementation. More info: http://www.vanheusden.com/time/jans/ (2015).»