2020-05-29, rev -03: The Network Time Protocol can operate in several modes. Some of these modes are based on the receipt of unsolicited packets, and therefore require the use of a service/well-known port as the local port number. However, in the case of NTP modes where the use of a service/well-known port is not required, employing such well-known/ service port unnecessarily increases the ability of attackers to perform blind/off-path attacks. This document formally updates RFC5905, recommending the use of port randomization for those modes where use of the NTP service port is not required.
↧