Destination Port UDP destination port number. In the case of unsymmetric mode and a client request this field is assigned the NTP service-port number 123, while for a server reply it is copied form the Source Port field of the client request. In the case of symmetric mode, both the Source Port and Destination Port fields are assigned the NTP
Windows Time service tools and settings | Microsoft Docs Windows Time follows the NTP specification, which requires the use of UDP port 123 for all time synchronization communication. This port is reserved by Windows Time and remains reserved at all times. Whenever the computer synchronizes its clock or provides time to another computer, that communication is performed on UDP port 123. TroubleshootingNTP < Support < NTP OpenNTPD also uses high-numbered source ports so if it is able to synchronize but ntpd is not, it is very probable that the incoming UDP port 123 is blocked. If you're going to run ntpd, you need to fix your network/firewall/NAT so that ntpd can have full unrestricted access to UDP port 123 in both directions. Public NTP (Network Time Protocol) Service
into my linux server (Ubuntu 8) I have top open the port 123 for ntp. I have write this into /etc/iptables.rules::INPUT ACCEPT [7496:9080183] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [4393:322232] [0:0] -A INPUT -p udp -m udp --sport 8100 -j ACCEPT [0:0] -A INPUT -p udp -m udp --dport 8100 -j ACCEPT [0:0] -I INPUT -p udp --dport 123 -j ACCEPT [0:0] -I OUTPUT -p udp --sport 123 -j …
RFC 958 - Network Time Protocol (NTP) Destination Port UDP destination port number. In the case of unsymmetric mode and a client request this field is assigned the NTP service-port number 123, while for a server reply it is copied form the Source Port field of the client request. In the case of symmetric mode, both the Source Port and Destination Port fields are assigned the NTP
Port 37 has been obsolete for a very long time and is one of the many archaic ports that should be disabled. NTP does not use 37 at all, only port 123. I would disable the following services in inetd.conf immediately, even if the security team has not reported them: daytime time echo discard chargen ntalk uucp
The firewall needs to be able to send traffic to the internet for DNS resolution of the NTP server host-names and of course for the NTP protocol itself (UDP port 123) If custom servers are desired, simply specify the host-names (FQDNs) or IP addresses of your NTP servers below. SonicWall - Allow connection from NTP servers - Spiceworks Dec 17, 2019 Why do Windows NTP queries use port 123 for both source Apr 04, 2020