Tinc is a Virtual Private Network (VPN) daemon that uses tunnelling and encryption to create a secure private network between hosts on the Internet.
The configuration and usage are extremely simpler that VPN based on IPSec protocol and is suited for not too complex infrastructures where OpenVPN is a better solution.
Tinc is a very good open source alternative to Hamachi (now LogMeIn), and it runs on every Unix flavour (Linux, OpenBSD, FreeBSD, NetBSD, …), and MS Windows and Mac OSX operating systems. It supports both IPv4 and IPv6 protocols and you can set up your IP configuration and requires limited bandwidth.
If you use Ubuntu you can easily install Tinc with the command : sudo apt-get install tinc.
Tinc drives all its traffic through the port 655, indeed be sure your firewall permits traffic through this port. In some circumstances, behind masquerading routers or firewalls, it is better to force Tinc to use only the TCP protocol with the option TCPOnly = yes.
