Re: Polipo web proxy

[Juliusz Chroboczek]

 On Wed, Aug 23, 2006 at 03:02:48AM +0200, Juliusz Chroboczek wrote:
  6) Polipo writes your hostname in every request. Either define proxyName
  to something else, or set [d]isableVia = true in your config file.

 This cannot be stressed enough.  Unfortunately, use of Via is a MUST
 according to RFC 2616 (it's not completely useless -- Polipo uses it
 to detect proxy loops).

 So if you want to follow the RFC, would it be adequate to use the
 pseudonym polipo in each case?

That's a somewhat radical approach to proxy loop avoidance ;-)

(It would disallow chaining proxies, and chaining proxies is a
somewhat common usage scenario -- when evading firewalls, or when
trying to work around a lossy wireless link.)

I guess I'll just make disableVia the default, and give up on my
policy of conforming by default.  People who actually care about loop
avoidance can enable it manually.

Juliusz

Polipo web proxy (was Re: Tor and Google Image search)

[Roger Dingledine]

On Fri, Aug 18, 2006 at 06:42:28PM -0500, Mike Perry wrote:
 Actually, I've started noticing this even though my privoxy config
 hasn't changed in a long while. I think its something new that
 images.google.com is doing that privoxy doesn't like.

Exciting. Thanks for tracking this down.

 Perhaps the images.google.com declairation should be added to the
 Privoxy that is shipped with vidalia/tor. It is likely to be pretty
 frustrating to new users.

What I'd like to do actually is move to some other http proxy one day.

(I once dreamed of taking the http proxy out of the loop entirely now that
Firefox supports safe socks, but it turns out that the entire networking
component of Firefox blocks during socks handshakes, so that is not an
option until somebody does a major overhaul of Firefox.)

I am thinking Polipo is a nice next option:
http://www.pps.jussieu.fr/~jch/software/polipo/
I've been using it the past month or two with good success. Can other
people here give it a try and see if we can clean it up? (You will need
the latest development version.)

Known issues when using Polipo with Tor:

1) In the config.sample, it suggests
socksParentProxy = localhost:9050
You should either change this to 127.0.0.1:9050, or enable the
dnsUseGethostbyname config option -- otherwise polipo asks your name
servers where localhost is, with possibly disastrous implications.

2) Polipo doesn't do as much application-level scrubbing as Privoxy tries
to do. But Privoxy isn't very good at it anymore anyway, and Firefox
is getting better. See previous threads about all the Firefox plugins
you need so you can discard Privoxy -- I recommend Noscript, Adblock,
and Adblock Filterset.G.

3) I've seen some funny behavior from its caching. But Privoxy also
gives funny behavior. And Polipo breaks fewer sites than Privoxy does. :)

4) It crashes (albeit rarely). The developer knows and is looking for
more clues.

5) I've never tried it on Windows. I don't think its developer has either.

6) Polipo writes your hostname in every request. Either define proxyName
to something else, or set DisableVia = true in your config file.

See also http://article.gmane.org/gmane.comp.web.polipo.user/1016

Thanks,
--Roger

Re: Polipo web proxy (was Re: Tor and Google Image search)

[Roger Dingledine]

On Fri, Aug 18, 2006 at 07:49:56PM -0500, Mike Perry wrote:
 7) The definition of parent proxy is different between Polipo and
 Privoxy. It turns out Privoxy has teh awesoma poweru of being able to
 have an HTTP proxy after Tor. This is useful for sites that block Tor,
 such as slashdot  wikipedia (for posting), craigslist, IRC, etc etc
 etc. I was unable to find a way for Polipo to do this. It made me
 sad. Course it aint exactly convenient for Privoxy, but at least it's
 there when you absolutely need to start some flame wars on /. ;)

Polipo can do this too. Just set both your parentProxy and your
socksParentProxy.

--Roger