enable ntpd for freebsd 6.1

1. put the following to /etc/rc.conf
ntpd_enable="YES"
ntpdate_enable="YES"
ntpd_flags="-p /var/run/ntpd.pid"

2. put the following to /etc/ntp.conf
server server1
server server2
driftfile /var/db/ntp.drift
restrict default ignore
restrict 10.0.201.0 mask 255.255.255.0 nomodify notrap

3. run 'ntpdate server1' to update time once
4. if you don't want to reboot, just run 'ntpd -p /var/run/ntpd.pid'