Privoxy

Open source; $0

Current Version: 3.0.10-1 (December 10, 2008) / 3.0.11 (February 23, 2009)

From the Privoxy web site: "Privoxy is a web proxy with advanced filtering capabilities for protecting privacy, modifying web page content, managing cookies, controlling access, and removing ads, banners, pop-ups and other obnoxious Internet junk. Privoxy has a very flexible configuration and can be customized to suit individual needs and tastes. Privoxy has application for both stand-alone systems and multi-user networks." Privoxy is freeware, released under the GNU General Public License.

Version 3.0.10-1 (the latest Mac OS X release) is a bugfix release; version 3.0.11 (the latest source release) adds/changes the following:

• On most platforms, outgoing connections can be kept alive and reused if the server supports it. Whether or not this improves things depends on the connection.
• When dropping privileges, membership in supplementary groups is given up as well. Not doing that can lead to Privoxy running with more rights than necessary and violates the principle of least privilege. Users of the --user option are advised to update.
• Passing invalid users or groups with the --user option didn't lead to program exit. Regression introduced in 3.0.7.
• The match all section has been moved from default.action to a new file called match-all.action. As a result the default.action no longer needs to be touched by the user and can be safely overwritten by updates.
• The standard.action file has been removed. Its content is now part of the default.action file.
• In some situations the logged content length was slightly too low.
• Crunched requests are logged with their own log level. If you used "debug 1" in the past, you'll probably want to additionally enable "debug 1024", otherwise only passed requests will be logged. If you only care about crunched requests, simply replace "debug 1" with "debug 1024".
• The crunch reason has been moved to the beginning of the crunch message. For HTTP URLs, the protocol is logged as well.
• Log messages are shortened by printing the thread id on its own (as opposed to putting it inside the string "Privoxy()").
• The config option socket-timeout has been added to control the time Privoxy waits for data to arrive on a socket.
• Support for remote toggling is controlled by the configure option --disable-toggle only. In previous versions it also depended on the action editor and thus configuring with the --disable-editor option would disable remote toggling support as well.
• Requests with invalid HTTP versions are rejected.
• The template symbol @date@ can be used to include a date(1)-like time string.
• Responses from shoutcast servers are accepted again.
• The hide-forwarded-for-headers action has been replaced with the change-x-forwarded-for{} action which can also be used to add X-Forwarded-For headers. The latter functionality already existed in Privoxy versions prior to 3.0.7 but has been removed as it was often used unintentionally (by not using the hide-forwarded-for-headers action).
• A "clear log" view option was added to the mingw32 version to clear out all of the lines in the Privoxy log window.
• The mingw32 version uses "critical sections" now, which prevents log message corruption under load. As a side effect, the "no thread-safe PRNG" warning could be removed as well.
• The mingw32 version's task bar icon is crossed out and the color changed to gray if Privoxy is toggled off.

The online release notes have more details.