What is NTP, and why does correct time matter for security?

NTP (Network Time Protocol) keeps the clocks of computers and network devices synchronised with an accurate time source. It sounds minor, but every log, alert and incident timeline depends on it. If the firewall is five minutes off, the server two hours off and a camera recorder set to the wrong year, nobody can reconstruct what happened in which order, and evidence for insurers, auditors or authorities becomes weak. Point all devices to the same reliable time source, check now and then that they agree, and record the time zone your logs use. It is one of the cheapest security measures there is.

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