IPsec may be configured to implement Virtual Private Networks (VPNs). A VPN may be used to securely link two or more networks over an insecure network (such as the Internet). For a minimal configuration, you need two Solaris 8 systems, each with two network interfaces. These two systems will serve as VPN gateways. Here is a step-by-step guide to setting up a Solaris 8-based VPN:
Disable all insecure and unneeded network services on both systems. (You may leave those that use strong encryption and authentication, such as Secure Shell.)
Disable IP forwarding.
Enable IP strict destination multihoming.
Configure Security Associations on both systems.
Configure the IPsec tunnel between the systems. ...