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Network Time Protocol

Network Time Protocol

Network Time Protocol definition

The Network Time Protocol (NTP) is a method used in computing to synchronize the clocks of different computers over a network. It’s designed to provide accurate and consistent timekeeping among all devices in a network by using Coordinated Universal Time (UTC) as a reference.

Although NTP is the most often used to keep network clocks in sync, it’s not the only one. Depending on the context, Precision Time Protocol (PTP) can provide even more precise time synchronization.

See also: synchronization, event log, Kerberos

Applications of the Network Time Protocol

  • Computer clock synchronization. NTP is most commonly used to synchronize the internal clocks of computers in a network. This way, all systems have a consistent, precise time that aligns with an agreed-upon standard. That is particularly important in systems where timing is crucial, such as financial transactions, industrial automation, and telecommunications.
  • Data log timestamping. Networked systems often log events and transactions for auditing, security, or diagnostic purposes. NTP can help ensure that these logs have accurate and consistent timestamps.
  • Network management. In networks, especially those handling critical data, accurate timing information can help identify and resolve issues. This could be anything from network latency to system failures.
  • Security. Many security protocols require accurate timestamps to function correctly. For example, the Kerberos authentication protocol uses timestamps to prevent replay attacks.

Network Time Protocol security concerns

  • Denial of service (DoS) attacks. An attacker can send a request to an NTP server with a spoofed IP address (the victim’s IP). Believing the request came from the victim, the NTP server sends the response to them. This may flood the victim’s network with unwanted traffic.
  • Man-in-the-middle attacks. An attacker can also intercept NTP traffic and alter timestamps before they reach the client. This could cause the client’s system time to be incorrect, leading to various issues.
  • Replay attacks. In a replay attack, a malicious actor intercepts network traffic and retransmits it later. They can be mitigated by using a timestamp in the communication, but it becomes a concern if the time protocol itself is compromised.

Further reading

Ultimate digital security