The NTP is designed to handle accidental or malicious data modification or destruction. These problems typically do not result in timekeeping errors on other time servers in the synchronization subnet. The success of this design is, however, based on the redundant time servers and various network paths. It is also assumed that data modification or destruction does not occur simultaneously on many time servers over the synchronization subnet. To prevent subnet vulnerability, select trusted time servers and allow them to be the clock sources.
NTP provides two security mechanisms: access authority and NTP authentication.
Access authority
Access control protects a local NTP service by setting the access authority. This is a simple measure to ensure security.
NTP authentication
Enable NTP authentication on networks that demand high security.