The VPN (Virtual Private Network) is a virtual private network, i.e.
an extension of the local area network towards a distant site through
another network (in general Internet). The data which forward via
Internet in this virtual private network are cryptées according to
various protocols (IPSec, PPTP, etc.) and algorithms (OF, AES, MD5,
SHA1, etc). Many routers ADSL general public have integrated
functionalities VPN (for example ZyXEL P-2602HW which combines ADSL,
VoIP in SIP, WLAN and VPN).