According to recommendations, the UDP port number assigned to both NTP and SNTP protocols is 123, which should be used in both the Source Port and Destination Port fields in the UDP datagram header. This parameter has got only informative value and cannot be modified. It activates/deactivates the SNTP Server functionality above mentioned.

Port 123 (tcp/udp) - Online TCP UDP port finder - adminsub.net Mar 30, 2016 What Is NTP? A Beginner's Guide to Network Time Protocol Mar 11, 2019 Using NTP for Time Settings - Confluence

NTP service is using UDP protocol to sync the time. So HTTP/TCP proxy may not work for it. Alternative to accepted answer, there is a good htpdate tool to sync time behind proxy. A cron job example: * 3 * * * /usr/bin/htpdate -s -P : www.linux.org www.freebsd.org

pool.ntp.org: NTP Servers in Portugal, pt.pool.ntp.org Portugal — pt.pool.ntp.org. We need more servers in this country. If you have a server with a static IP, please consider joining the pool! To use this specific pool zone, add the following to your ntp.conf file: server 3.pt.pool.ntp.org server 3.europe.pool.ntp.org server 0.europe.pool.ntp.org Government Services | NTP

Google turns on free public NTP servers that SMEAR TIME

Government Services | NTP Search for Country Code & Port Code . Search for the country codes and port codes. Click here . Voluntary Disclosure Programme (VDP) NTP supports the current and previous release versions of Safari, Internet Explorer, Firefox, Chrome and Opera web browsers. NIST Internet Time Service Users are *strongly* encouraged to upgrade to the network time protocol (NTP), which is both more accurate and more robust. 2. Users of the NIST "DAYTIME" protocol on tcp port 13 are also strongly encouraged to upgrade to the network time protocol, which provides greater accuracy and requires less network bandwidth. How to configure NTP and DST - Hikvision • NTP Port: Port of NTP server. Default as 123. 5. Click the Apply button to save and exit the interface. 6. Or configure it via web browser in the interface below. Note: The time synchronization interval can be set from1 to 10080min, and the default value is 60min. If the NVR is connected to a public network, you should use a NTP server that Configure Internet Time (NTP) options in Windows 10