Categorizing VPN Security Models

From the security standpoint, either the underlying delivery network is trusted, or the VPN must enforce security with mechanisms in the VPN itself. Unless the trusted delivery network runs only among physically secure sites, both trusted and secure models need an authentication mechanism for users to gain access to the VPN.

Some ISPs now offer managed VPN service for business customers who want the security and convenience of a VPN but prefer not to undertake administering a VPN server themselves. Managed VPNs go beyond PPVPN scope, and are a contracted security solution that can reach into hosts. In addition to providing remote workers with secure access to their employer's internal network, other security and management services are sometimes included as part of the package. Examples include keeping anti-virus and anti-spyware programs updated on each client's computer.

Authentication before VPN Connection

A known trusted user, sometimes only when using trusted devices, can be provided with appropriate security privileges to access resources not available to general users. Servers may also need to authenticate themselves to join the VPN.

There are a wide variety of authentication mechanisms, which may be implemented in devices including firewalls, access gateways, and other devices. They may use passwords, biometrics, or cryptographic methods. Strong authentication involves combining cryptography with another authentication mechanism. The authentication mechanism may require explicit user action, or may be embedded in the VPN client or the workstation.