Red Hat Security Advisory 2015-1459-01 - The Network Time Protocol is used to synchronize a computer's time with another referenced time source. It was found that because NTP's access control was based on a source IP address, an attacker could bypass source IP restrictions and send malicious control and configuration packets by spoofing ::1 addresses. A denial of service flaw was found in the way NTP hosts that were peering with each other authenticated themselves before updating their internal state variables. An attacker could send packets to one peer host, which could cascade to other peers, and stop the synchronization process among the reached peers.
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