"... OmniSync is a driver for NTPd for people who are firewall-challenged. It enables systems to sync time when port 123 (UDP) is blocked.
It allows you to sync against the daytime service (port 13 tcp/udp), time (port 37 tcp/udp), SNTS, ICMP, SNMP, precision time protocol (PTP - IEEE 1588), (S)NTP via a socks5 proxy server, http and https (both also via proxy server).
It doesn't directly set the clock but uses NTPd for this as this enables you to have multiple time sources as well as bad-chimer detection etc ... "