Popular Proxy Software

Squid Cache
Squid Cache is a web caching daemon and a proxy server. It is free software that is governed by the GNU General Public License. It caches repeated requests, caches DNS, net and other network look-ups in order to enhance security by filtering traffic. It essentially runs on UNIX-like systems. It is popularly considered robust and complete. It is designed for HTTP and FTP but other protocols like SSL, TLS, HTTPS, and Internet Gopher also work well with Squid. Squid works as a web proxy and a reverse proxy server. It helps making connections anonymous by modifying or disabling the header fields in the HTTP request of the client. As a reverse proxy server Squid caches requests from unlimited clients from a single web server.

HTTP Tunnel
This is a program using which application data is masked as HTTP in order to bypass firewalls. All outgoing traffic is routed through port 80. Port 80 is the standard HTTP port. The traffic is then encapsulated in HTTP packets. HTTP traffic is allowed to go through most firewalls hence the applications can communicate with remote hosts. Transfer security is maintained by data encryption. SOCKS protocol must have been implemented in order to use HTTP Tunnel. Peer-to-peer clients, instant messages and web browsers can use HTTP Tunnel. The tunnel is maintained by mediator servers.

Apache HTTP Server
It is a web server that is implemented in UNIX-like systems, Novell NetWare, Microsoft Windows as well as other operating systems. It can be configured to act as a proxy server.

WinGate
It is an Integrated Gateway Management System. It works on Microsoft Windows and provides Firewall and NAT. It consists of multiple integrated proxy servers. Internet access is provided at three levels:
1 Firewall with NAT at the packet level
2 Proxies at the circuit level
3 Multiple proxy servers
It features a WWW Proxy that allows easy administration as the proxy is transparent. The problem with the proxy was that it had a default configuration that was insecure. It allowed third party traffic through the server.