ntpdate into cron seems to be no longer a good idea.
What is an
- environmental friendly ;-)
way of keeping a (debian) server's time clock up to date?
apt-get install ntp. If you've never had it installed before, you should be good to go. If you have, and therefore, might have stale config files, you could
apt-get remove --purge ntp and
apt-get install ntp again to get new config files. Or if you want to keep your config files, I recommend checking that
NTPD_OPTS='-g'. This says to ntpd "try to correct the time, even if it is way off", and make sure at least one good server in
/etc/ntp.conf has the
iburst option, like:
server 0.debian.pool.ntp.org iburst
This allows a burst of packets to be sent which will get your time synced quicker.
If you ever need to have something wait for time sync before proceeding, run
ntp-wait. If, for example, you have a service which shouldn't start until you are sure you have your time corrected. (which you previously might have used ntpdate for)
Couldn't you just set ntpd to start at boot as suggested on the mailing list? That's what I've been doing for as long as I can remember.