Depending on your Linux distribution, there is usually a date/time configuration setting in an administration menu. You can configure that your system should use network time protocol (NTP) synchronization.
This will initially use Internet servers (like those at
http://www.pool.ntp.org/) to establish the hardware clock drift on your machine, then create a drift correction file (after about 2 weeks of sampling and correction) that NTP will use to maintain sub-100ms clock accuracy, even without a network connection.
time server
