Entries tagged privoxy

It bothers me that my Tor usage is less than I'd like because it is just so fiddly.

When it comes to privacy I want to keep things simple, I want to use tor, but I dont want to use it for things that aren't sane.

In practise that means I want to use tor for a small amount of browsing:

• When the host is a.com, b.com, & c.com
• When the traffic is not over SSL.

To do that I have to install privoxy, and use that with a configuration file like this:

# don't forward by default.
forward-socks4   /    .
# don't forward by default, even more so for HTTPS
forward-socks4   :443 .

# but we do want tor on these three sites:
forward-socks4   a.com/       127.0.0.1:9050 .
forward-socks4   b.com/       127.0.0.1:9050 .
forward-socks4   c.com/       127.0.0.1:9050 .

I'm using absolutely nothing else in my Privoxy configuration, so it seems like overkill.

I'd love to hear about a simple rule-based proxy-chaining tool - if there is one out there then I'd love to know about it lazyweb.

If not it shouldn't be too hard to write one with the Net::Proxy & Net::Socks module(s).

<global>
  listen 1234
  no-proxy
</global>

<sites>  
  hostname one.com
  port != 443
  proxy socks localhost 8050
</sites>

<sites>  
  hostname two.com
  port != 443
  proxy socks localhost 8050
</sites>

<sites>
  hostname foo.com
  port = 80
  proxy localhost 8000
</sites>

Tags: privoxy, todo, tor | 7 comments

It is interesting that François Marier recently posted a brief "howto" document on debugging problems caused by overly-agressive filtering with privoxy, as I've recently been having problems with that tool.

My home network frequently changes configuration depending on what I'm concentrating upon, but every few months I'll start/cease using the following tools:

• squid - The caching proxy server.
• tor - The onion router.
• privoxy - The filtering cache.

Recently I was experimenting with XSS attacks against various browsers, which meant using them for real. As not all browsers have the same anti-advert setups I was running privoxy to filter out web-annoyances, and I spotted a major flaw with it.

Unfortunately I can only describe the problem, not reproduce it, or track it down. I'm 80% certain the bug is in privoxy, but the stack is suitably high that determining that for sure is problematic.

In short the issue is that HTTP requests would end up being sent to the wrong host:

• I load my start page in one tab: http://www.steve.org.uk/start/
• I click to open the following URL in another tab: http://www.perlmonks.org/?node=Newest Nodes.
• The request gets sent to http://steve.org.uk/?node=...

After that clicking around consistently sends requests to the first HTTP host which was accessed succesfully. So, for example, attempting to visit http://foo.com/bar/ will send the request to http://steve.org.uk/bar - which then gives a 404.

In terms of setup I use a dnsmasq DNS cache, privoxy and iceweasel from Debian unstable. From the symptoms I'm not sure if iceweasel's "KeepAlive" system is to blame, or if privoxy has a bad cache of hosts. Perhaps it is dnsmasq returning bogus DNS data, or my cable connection itself having DNS issues.

Anyway once the symptoms present themselves closing the browser and restarting the cache fixes it. Until the next time which might be hours or days later.

I'd report it as a bug - but I don't know where it should be. Privoxy caching things it shouldn't? iceweasel having keepalive issues? dnsmasq returning wrong DNS entries?

I'd ask "Have you seen this before, internet world?" but I guess if you have tracked it down it'd be fixed by now, and it clearly isn't!

Anyway for the moment I've uninstalled privoxy.

ObFilm: Pulp Fiction

Tags: bugs, privoxy, proxies, random | 4 comments