ntp-server 1:4.2.0a+stable-8.1ubuntu5 (amd64 binary) in ubuntu dapper

 NTP, the Network Time Protocol, is used to keep computer clocks accurate
 over the Internet, or by following an accurate hardware receiver which
 interprets GPS, DCF-77, NIST or similar time signals.
 .
 This package holds the common files for the NTP server and all programs
 which need to run on the actual server.
 .
 There are two server packages: 'ntp-simple' only knows about your computer's
 built-in clock. 'ntp-refclock' has built-in support for a variety of
 time signal receivers. Both server packages, of course, can synchronize
 with other servers across the Internet.