Re: warning message question

[Karsten Loesing <karsten.loesing@xxxxxxx>]

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On 07/26/2009 09:52 AM, Roger Dingledine wrote:
> On Sun, Jul 26, 2009 at 02:32:45AM -0500, Scott Bennett wrote:
>>      Saturday morning, I got the following message.
>>
>> Jul 25 09:33:57.004 [warn] Received http status code 502 ("Proxy Error") from server '80.190.246.100:80' while fetching consensus directory.
>>
>> Can anyone explain the situation(s) that can result in such a message?
> 
> 80.190.246.100:80 is the DirPort on gabelmoo, one of the v3 authorities.
> So your relay was trying to get an updated version of the v3 consensus
> from gabelmoo.
> 
> It looks like the way gabelmoo is listening on port 80 is by proxypassing
> it through apache. You can read more about that approach in this poorly
> organized faq entry:
> https://wiki.torproject.org/noreply/TheOnionRouter/TorFAQ#ServerForFirewalledClients
> 
> and at that particular moment, for some reason apache decided that
> sending back a 502 proxy error was better than passing your request on.

FYI, gabelmoo is passing directory requests through Apache for two
reasons: First, I have been using Apache as a first attempt to measure
how long clients take to download network statuses in order to derive
how fast clients are; this functionality is now in 0.2.2.0-alpha-dev, so
that Apache is not required anymore for this:

http://archives.seul.org/or/cvs/Jul-2009/msg00244.html

Second, I'm using port 80 both for serving the Tor directory and for
serving files for performance measurements:

http://freehaven.net/~karsten/volatile/torperf-2009-07-01.pdf

> For example, I bet this could happen if the gabelmoo relay was down at
> the time.

It's back online now.

- --Karsten

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