Chrony

is Article description::a versatile implementation of the [[Network Time Protocol (NTP).]] It can synchronize the system clock with NTP servers, reference clocks (e.g. GPS receiver), and manual input using wristwatch and keyboard. It can also operate as an NTPv4 (RFC 5905) server and peer to provide a time service to other computers in the network.

Emerge
Install the chrony package:

Configuration
is the configuration file for. The default configuration is populated with:

On systems where a network connection is not always available at boot (laptops, etc.), it might help to change the pool line in the server configuration:

This tells chronyd that the machine will be assumed to have gone offline when 2 requests have been sent to it without receiving a response. You will need to use the command to re-enable polling (See below)

Enable Network Time Security (NTS)
NTS provides cryptographic security on NTP client-server connections using Transport Layer Security (TLS) and Authenticated Encryption with Associated Data (AEAD) (RFC 8915). In order to use this you need to set specific servers supporting NTS:

Use UTC time
chronyd assumes by default that the RTC keeps local time (including any daylight saving changes). To use UTC instead use:

Acting as a local NTP server
By default, only synchronizes the local machine time. By adding allow and deny rules, it will act as a local NTP source:

chronyc Client Interface Tool
is a command-line interface program which can be used to monitor chronyd's performance and to change various operating parameters whilst it is running. A full list of commands can be found in the manual,

Examples:

OpenRC
Add to the default runlevel to have the time synchronized automatically.

To monitor status of the server:

systemd
To run the sync service:

To have the sync service start at boot:

To monitor status of the service:

External resources

 * https://wiki.archlinux.org/index.php/Chrony
 * RFC 5905 - Network Time Protocol Version 4: Protocol and Algorithms Specification
 * RFC 7822 - Network Time Protocol Version 4 (NTPv4) Extension Fields
 * RFC 8573 - Message Authentication Code for the Network Time Protocol
 * RFC 9109 - Network Time Protocol Version 4: Port Randomization