Open Source Python VPN Software for Windows

CacheGuard Gateway is a free and open-source Unified Threat Management (UTM) solution, a Web Application Firewall (WAF), and a Quality of Service (QoS) platform designed to optimize WAN traffic. To obtain a CacheGuard Gateway appliance, download CacheGuard-OS and install it on the bare-metal or virtual machine of your choice. It’s that simple and completely free. The UTM includes a firewall, web antivirus, VPN server, and a URL-filtering and SSL-inspection web proxy. The WAF operates in conjunction with a reverse proxy, web application load balancer, and SSL offloader, and is capable of blocking malicious requests as well as traffic from IP addresses with poor reputations. The QoS manager enables traffic shaping to prioritize critical network flows, load balance multiple WAN links, and cache web traffic.

Endian Firewall Community (EFW) is a "turn-key" linux security distribution that makes your system a full featured security appliance with Unified Threat Management (UTM) functionalities. The software has been designed for the best usability: very easy to install, use and manage and still greatly flexible. The feature suite includes stateful packet inspection firewall, application-level proxies for various protocols (HTTP, FTP, POP3, SMTP) with antivirus support, virus and spam-filtering for email traffic (POP and SMTP), content filtering of Web traffic and a "hassle free" VPN solution (based on both OpenVPN and IPsec).