In Firefox is add-on FoxyProxy, which makes possible use many proxy with filtering URLs. I need it for any browser, but in many of them it is only possible to set one proxy server. I need a transparent local proxy, which may filters URLs and forwards traffic to other proxies. I've heard about Squid, but I haven't found information about it. It is possible to set it in Linux (and how)?

2 Answers 2


Most browsers that support Javascript also support Netscape-style proxy autoconfiguration (PAC) files (I'm not aware of a JavaScript-capable browser released this century that doesn't). PAC files contain JavaScript code that is executed to determine what proxy (if any) to use for each request.

function FindProxyForURL(url, host) {
    if (shExpMatch(host, "*.example.com")) {
        return "DIRECT";
    } else if (shExpMatch(host, "somewhere.else")) {
        return "PROXY someproxy:8080";
    } else {
        return "PROXY default-proxy.example.com:3128";

To have a single setting for browsers and other applications that don't support Javascript, you'll need a proxy that supports per-URL parent proxies.

Squid is one possibility, it's a caching proxy designed for high loads and with many features. See Squid selects parent depending on requested URL? for examples of how to set up per-URL parent proxies.

Wwwoffle is another possibility. This proxy is strongly oriented towards having an offline cache, and caches more aggressively than is allowed by the HTTP standards, which is a problem with some sites. Parent proxies can be specified per-URL with wildcard patterns (the default configuration files contains commented-out examples).


The answer here is going to be to set your single value to a proxy server of your own so that all traffic hits it. This can be a system wide setting.

As for setting up your own proxy server, yes squid is the best option I know of and yes it can be setup and run on a Linux machine. It is best run on a gateway/router machine, but you can run it on your personal machine for use locally as well. There are lots of guides available for how to configure it. They cover a wide range of possible uses, you should search specifically for whatever kind of configuration you want to accomplish.

  • It isn't answer. I'm looking for a possibility using many proxies not one. About first part your answer I've heard, but it is for one proxy. I've written: "I've heard about Squid, but I haven't found information about it". I've meant that I haven't found information about option, which makes possible to set many proxies (for example: for google.pl run first_proxy.com, for other sites run second_proxy.com).
    – godlark
    Aug 1, 2011 at 16:32
  • 1
    @godlark: The point is that to use many proxies from some program that only supports using one, you need to setup ONE proxy that can then itself connect to as many others based on whatever rules you need.
    – Caleb
    Aug 1, 2011 at 16:33
  • Yes I know :) But I search information about proxy serwer with these possibilities. Thanks for answer.
    – godlark
    Aug 1, 2011 at 16:37

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