You can use ntpdate command to update date and time from Internet in Ubuntu. You can synchronize with global server such as pool.ntp.org. The pool.ntp.org project is a big virtual cluster of timeservers providing reliable easy to use NTP service for millions of clients. This is the command.
$ sudo ntpdate id.pool.ntp.org
You can change id.pool.ntp.org to your appropriate location such as jp.pool.ntp.org (Japan), de.pool.ntp.org (Germany), etc.