Bruce Schneier's FAQ concerning Microsoft's PPTP Implementation - Bruce Schneier Analysis of the Microsoft PPTP implementation. Why is PPTP bad.
Configuring an IPsec tunnel between Openswan and Windows - This document gives you the details how to setup a virtual private network between Linux/Openswan on one side and Microsoft Windows 2000 and XP on the other side.
Freeswan and a Cisco PIX 501 - Creating an interoperable VPN using the free FreeSWAN/Openswan and a Cisco PIX 501.
German book covering Linux VPNs - This site offers a German book (pdf) covering Linux VPNs for download.
Information about Check Point VPN-1/FireWall-1 - This site gives valuable information about the Checkpoint VPN-1 product and its interoperability with other VPN implementations.
An Intro To SSL VPN - An article discusses the types of VPN available, benefits, and considerations necessary when deploying SSL VPNs.
L2F - CISCO's Layer Two Forwarding protocol
Linux VPN Howto using SSH and PPP - This howto describes the setup of a simple VPN using ssh and ppp.
Microsoft's PPTP FAQ - Point-to-Point-Tunneling Protocol (PPTP) is a networking technology that supports multiprotocol virtual private networks (VPN).
NG FAQ - VPN with FreeS/WAN - by AERAsec - This document covers the steps and pitfalls connecting a CheckPoint NG FW-1 to a FreeSWAN Linux-Box using preshared keys and X.509 certificates.
Official IPsec Howto for Linux - This howto describes the step to take when setting up a Linux based VPN.
OpenVPN 2.0 HOWTO - This howto describes the setup of the IPsec alternative OpenVPN, which is available for Win32, MacOS X and Unix-based Operating Systems.
OpenVPN using X.509 certificates - This document explains how to deploy a VPN using OpenVPN and OpenSSL.
Poptop MSCHAP2 ADS - This Howto describes the steps to setup a Linux PopTop PPTP Server using MSCHAPv2. For Authentication either Radius or an Active Directory Domain controller may be used.
Replacing a Windows PPTP server with Linux - Replacing a Windows PPTP server with Linux PopTop.
Using a Linux L2TP/IPsec VPN server - This document gives you the background and show the steps for implementing an L2TP/IPsec based VPN using Linux, Windows and MacOSX
Virtual Private Networks (VPN) - This document discusses key concepts related to Virtual Private Networks
What Is A Virtual Private Network? - A Network Computing Online Article