Overview

This guide describes how to configure and operate the Shrew Soft VPN Client with an open source VPN Gateway. By tunneling traffic between the VPN Client and the VPN Gateway, the host is able to access private network resources in a manner which is secure even when connecting from an insecure public network.

This functionality is provided by implementing the IPsec Protocol standard which is used by a wide variety of both commercial and open source operating systems.

Many commercial VPN Gateways are available on the market. Most of these products are bundled with proprietary VPN Client software that is designed to communicate with a specific gateway device. While most major open source operating systems have had support for basic IPsec functionality for some time, they have lacked a sophisticated IKE daemon and kernel support for protocol extensions that would be required to properly support IPsec Client connectivity. Luckily this is no longer the case. Recent improvements to the IPsec Tools software and added kernel support for features such as NAT Traversal have enabled open source operating systems such as Linux, FreeBSD and NetBSD to be considered as a viable alternative to expensive commercial VPN gateway solutions. The Shrew Soft VPN Client offers a complimentary Windows IPsec implementation that can be used to communicate with these gateways.