A virtual private data network enables distributed
private networks to communicate securely with each other
over insecure public networks. A VPN can be contrasted
to a system of owned or leased lines that can only be
used by one company giving it the benefit of a private
network, while utilizing the cost advantages of the
public infrastructure. Privacy is maintained through the
use of a tunneling protocol and through security
procedures.
VPN implementations typically fall in three categories:
intranet, extranet, and secure remote access. VPNs can
be dynamic or static. Static VPNs are up full-time,
while Dynamic VPNs operate on demand and are more
commonly used for mobile workers and telecommuters.
