Anti-censorship tools (proxyTools) consists of a huge Perl application (localProxy) and a set of tools to analyze the user's network (proxies, firewall rules, name servers, etc.). LocalProxy abstracts external services in an uncensored, reliable, fast manner to the localhost, where they may be used by standard clients (Web browsers, Usenet news clients, SOCKS-capable clients, etc.). Various combinations of strategies are tried to ensure the non-censored nature of the information, and multiple, parallel services (e.g. HTTP proxies) are used to ensure reliability and speed. The tools are capable of automating collection of the data required for localProxy. LocalProxy builds a configuration for the user and dynamically adjusts to using the fastest strategies and proxies available to it. The tools are useful for network analysis (firewall rules, proxy capabilities, etc.) independently of localProxy.
connect-tunnel is a simple Perl script that lets you tunnel anything through a CONNECT-aware HTTP proxy. It supports multiple tunnels and multiple connections to those tunnels, and all of the authentication methods that libwww-perl supports (Basic, Digest, and NTLM). It works under Unix and Windows.
postprox is a minimal Postfix SMTP proxy which copies an SMTP conversation between its input and another SMTP server, but spools the DATA portion to a temporary file and runs a specified program on it before passing it on to the output server. It can potentially output an SMTP error code instead of the data if the content filter says to do so.