Time is money!
It’s important, from a lot of points of views besides security, ot keep the server time correct. The tool to use is ntpdate which syncs server time to a NTP server (Network Time Protocol)
Put this in your crontab if your server is in the NA vicinity
5 0 * * * /usr/sbin/ntpdate -u 0.north-america.pool.ntp.org
This will sync the clock to the NTP server at five past midnight.
For a complete list of which servers to use check here