ntp-server 1:4.2.0a+stable-8.1ubuntu2 (amd64 binary) in ubuntu dapper

Network Time Protocol: common server tools
 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.