AdvTor

[Fabian Keil]

Anon Mus <my.green.lantern at googlemail.com> wrote:

> andrew at torproject.org wrote:
> > On Thu, Oct 07, 2010 at 05:20:08PM +0100, my.green.lantern at googlemail.com wrote 2.3K bytes in 55 lines about:
> > : Well, well, well.... suddenly the problem fixes "itself"... after
> > : 20+ disconnects and 10+ "You are using a proxy which is changing
> > : your data... refusing connection.." over the past 3 days.
> >
> > This would be a lot better if it came with logs, bug reports, and data.
> > It could also be the destination site having problems, or the exit relay
> > is overloaded, or sun flares.  The Internet is complex, narrowing down
> > the problem to Tor or not Tor is a first step.
> >
> >   
> I have no idea how to log (privoxy or tor??) these, maybe you could 
> explain how its done, just in case they start happening again..
> 
> 1. Connection Disconnected:
> 
> The browser has a little message "connection closed" on a white 
> background (not a privoxy message).

If the server (or proxy) accepts the connection but closes
it without sending any data, Privoxy versions before 3.0.7
will send the text 'Connection: close' to the client.

This bug was fixed more than three years ago and is yet
another reason why you might want to consider updating
your Privoxy version.

Nowadays you get a proper problem description:

|fk at r500 ~ $lynx --dump http://10.0.0.1/empty-response
|   502
|
|       This is [1]Privoxy 3.0.17 on Privoxy-Jail.local (10.0.0.1), port 8118,
|       enabled
|
|   Warning:
|
|      This Privoxy version is based on UNRELEASED code and not intended for
|      production systems!
|      Use at your own risk. See the [2]license for details.
|
|   No server or forwarder data received
|
|      Your request for [3]http://10.0.0.1/empty-response could not be
|      fulfilled, because the connection to 10.0.0.1 (10.0.0.1) has been
|      closed before Privoxy received any data for this request.
|
|      This is often a temporary failure, so you might just [4]try again.
|
|      If you get this message very often, consider disabling
|      [5]connection-sharing (which should be off by default). If that doesn't
|      help, you may have to additionally disable support for connection
|      keep-alive by setting [6]keep-alive-timeout to 0.
[...]

It's still a frequent "problem" when using Tor. Yesterday it happened
for around 1% of my requests (some of them were made without Tor, though):

fk at r500 ~ $privoxy-log-parser --statistics /usr/jails/privoxy-jail/var/log/privoxy/privoxy.log.1
Client requests total: 7881
Crunches: 1100 (13.96%)
Outgoing requests: 6781 (86.04%)
Server keep-alive offers: 2802 (35.55%)
New outgoing connections: 5535 (70.23%)
Reused connections: 1246 (15.81%)
Empty responses: 95 (1.21%)
Empty responses on new connections: 1 (0.01%)
Empty responses on reused connections: 94 (1.19%)
Method distribution:
    7052 : GET     
     753 : CONNECT 
      46 : POST    
Client HTTP versions:
7830 : HTTP/1.1
21 : HTTP/1.0
URL statistics are disabled. Increase --url-statistics-threshold to enable them.

Note that it isn't necessarily caused by the exit node itself,
it can also happen simply because the server closed the connection
but the Tor client hasn't noticed it yet and thus still accepts
data on an already-dead connection. This would explain the number
of "Empty responses on reused connections".

Fabian
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 196 bytes
Desc: not available
URL: <http://lists.torproject.org/pipermail/tor-talk/attachments/20101009/ceadfec8/attachment.pgp>