Port 123 (tcp/udp) - Online TCP UDP port finder - adminsub.net

Network Time Protocol (NTP) Issues Troubleshooting and NTP uses User Datagram Protocol (UDP) port 123. Create ACL 101: access-list 101 permit udp any any eq 123 access-list 101 permit udp any eq 123 any NTP packets usually have a source and destination port of 123, so this helps: permit udp any eq 123 any eq 123 ; Use this ACL in order to limit output from the debug ip packet command: NTP - The Wireshark Wiki However, you can filter on the well known NTP UDP port 123. Capture only the NTP based traffic: udp port 123; On many systems, you can say "udp port ntp" rather than "udp port 123". External links. Current RFC: RFC 5905 Network Time Protocol Version 4: Protocol and Algorithms Specification. Obsoleted RFCs: RFC 958 Network Time Protocol. RFC NTP 13 (B) - Flag Guys NTP 13(B), FLAGS, PENNANTS AND CUSTOMS, was developed under the direction of the Commander, Naval Telecommunications Command, and is promulgated for use by the U.S. Navy and Coast Guard. Network Time Protocol, NTPv3, NTPv4, Time Servers

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

Why do Windows NTP queries use port 123 for both source Apr 04, 2020

NTP uses User Datagram Protocol (UDP) port 123. Create ACL 101: access-list 101 permit udp any any eq 123 access-list 101 permit udp any eq 123 any NTP packets usually have a source and destination port of 123, so this helps: permit udp any eq 123 any eq 123 ; Use this ACL in order to limit output from the debug ip packet command:

If you configure NTP on teh router then it's going to open the port so that it'll listen to packets on it. The above config will ensure that if the router receives an NTP packet from anywhere else it'll drop it, but there's no way to actually only open the port for that IP address. OpenWrt Project: NTP client / NTP server An ntpd server should be listening on the default NTP port (UDP 123). Configuration. The busybox-ntpd is configured in /etc/config/system. By default, it runs as a client and does not serve time to other peers. A server can be enabled by adding the flag “-l” to “local args” in /etc/init.d/sysntpd (line 23). Starting with Backfire 10.3.1