Privoxy

Privoxy runs a local proxy server that acts as a privatizing layer that can strip traffic of certain contents.

By running all of your traffic through Privoxy, you can remove things like Javascript, unrecognized or strange HTML headers, prevent redirects, stop animated GIFs from playing, remove ads, and many, many more things.

The Privoxy User Manual: http://www.privoxy.org/user-manual/

First Things First

What Privoxy Does

Privoxy is a proxy server. A proxy server is a middleman, between you and the web. You pass requests to the proxy server, and the proxy server makes the actual request for you. Privoxy is usually run as a local proxy server, and it is used to filter the content that passes through it.

Privoxy acts as a filter for your web traffic. That means you can tell it to block images, block ads, block scripts. You can tell it not to follow redirects, or to find/replace expressions, or block cookies, or filter cookies, or any number of different things (see Privoxy User Manual section "Actions" http://www.privoxy.org/user-manual/actions-file.html#ACTIONS)

What Privoxy Does NOT Do

Privoxy does not anonymize your browsing. Privoxy does not change your IP. Privoxy does not encrypt your traffic.

Privoxy should be thought of as the final layer in a multiple-layer stack of security. Privoxy is a content firewall, and it filters the very final result of the content fetched over HTTP or HTTPS or Tor or whatever service you have hooked up to Privoxy. Privoxy filters out unwanted or malicious content that can be used to identify and track you.

It's important to keep in mind, that although Privoxy does things to help you remain anonymous by blocking HTML elements, that does not make it an anonymization tool. It just filters out content after it has reached your computer, and does not change how the traffic looks when outside of the machine in any way.

Privoxy is like putting a fence up around your house - it won't hide where your house is. You're just keeping bad stuff out.

Privoxy and Friends

Even though Privoxy cannot provide you with anonymity, you can combine Privoxy with other tools that can! For example, you can use Privoxy with Tor, another local proxy server, by running your web traffic through Privoxy, then through Tor.

More notes on anonymous browsing here: Anonymous Browsing

Getting Set Up

Installing Privoxy

It is pretty easy to install if you use Kali or similar OS with a good package manager:

$ apt-get install privoxy

Configuring Privoxy

You can configure privoxy by editing its configuration file, /etc/privoxy/config

While there are many options, all well-documented in the Users Manual, the key line here is:

listen-address  127.0.0.1:8118

This is how you run Privoxy if you're a single user, filtering traffic for a single computer.

(Note that you can also run a Privoxy server, and perform filtering for multiple users.)

Starting Privoxy

You can start Privoxy (assuming it is installed on your system as a service) via:

$ service privoxy start

Using Privoxy with your Browser

Now you can configure your browser to use the proxy server at 127.0.0.1, port 8118 (that's Privoxy!)

Change the proxy server for HTTP and HTTPS protocols (or, ALL protocols) to be 127.0.0.1, port 8118.

You can do this in the native browser, a la Firefox Preferences (not recommended), or you can use a browser add-on to switch between different proxies (much better).

Is Privoxy Running?

Check on the status of your privoxy instance by going to http://config.privoxy.org or http://p.p and you will see a page with some information about Privoxy (assuming it is running).

You can also view your rules and configuration files.

If you edit the configuration file, and set the flag

enable-edit-actions 1

then you can actually edit the rules in the browser. But this is vulnerable, and is disabled by default for a reason - don't leave it on!