Dante is a free implementation of the proxy protocols SOCKS version 4 and SOCKS version 5 (RFC 1928). It can be used as a firewall between networks, controlling outgoing traffic. The package consists of two parts: a socks server and a proxy client that supports socks, HTTP proxies, and UPnP. RFC 1961 (GSSAPI) is supported in both the client and the server. Commercial support is available.
FilterProxy is a Perl script that acts as a generic Web proxy. It is unique in that it allows you to install modules that can perform arbitrary transformations on HTML (or any other MIME-type) and HTTP headers. It filters ads by stripping HTML from the page, anonymizes requests by removing Referer and User-Agent headers, compresses HTML content, and de-animates animated gifs. Configuration is done via Web-based forms or editing a Perl data structure.
Frox is a transparent FTP proxy that runs under Linux and *BSD. It should also work on other UNIX OSes that use ipfilter. It supports caching of FTP downloads, either by redirecting through a Squid proxy, or through its own local cache. Downloads may also be transparently scanned for viruses (through an external scanner). Additionally there is an interface for writing scripts to add features or modify frox's behavior, and examples are included to limit download file size and to transparently direct connections to specific hosts to mirror servers. The proxy is written with security in mind, and in the default setup runs as a non-root user in a chroot jail.
HTTPGate is a filtering HTTP Gateway originally intended to enchange user's privacy when surfing on the net, but it can also be used to avoid censorware systems in web browsing. HTTPGate operates on a user definable internet port where the user connects using a web browser. The main page shows a text box and a set of options user can choose to avoid transmitting some information during client/server negotiation.
Jonama is a piece of software acting as a relay between a client over the Net and your internal systems. It was developed which security in mind, ie. it makes use of the SSL protocol to identify remotes and crypt channels and uses Unix mechanisms like chroot and setuid to minimize rights and actions.