pfSense - pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi WAN, and more
CCProxy - Want to share Internet connection? Get every computer online through a single Internet connection?
Zentyal - Linux directory, domain, mail, gateway and infrastructure server for SMBs.
Apache Traffic Server - Fast, scalable and extensible HTTP/S 2 and 1.1 compliant caching proxy server.
NethServer - NethServer is an operating system for Linux enthusiasts, designed for small offices and medium...
3proxy - 3proxy freeware proxy server for Windows and Unix. HTTP, SOCKS, FTP, POP3