Why do Windows NTP queries use port 123 for both source

This is because all NTP servers need access to User Datagram Protocol (UDP) port 123, and as long as the Windows Time service is running on the Windows Server 2003 operating system, port 123 remains reserved by Windows Time. Network Ports Used by Windows Time Service How to test if my home router is blocking NTP port 123 Jun 04, 2002 List of TCP and UDP port numbers - Wikipedia 248 rows How To Configure NTP Server in Windows Server 2019

22.14. Configure the Firewall to Allow Incoming NTP

Network Time Protocol - Wikipedia Implementations send and receive timestamps using the User Datagram Protocol (UDP) on port number 123. They can also use broadcasting or multicasting, where clients passively listen to time updates after an initial round-trip calibrating exchange.

Can't add a NAT rule, NTP port 123 is used - NETGEAR

iptables - ubuntu: open udp port 123 - Server Fault 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 … Internet Time Service Firewall information | NIST