Re: [tor-talk] Orbot v14 alpha: obfsclient, Tor 0.2.5.3-alpha

[George Kadianakis <desnacked@xxxxxxxxxx>]

Nathan Freitas <nathan@xxxxxxxxxxx> writes:

> On 05/04/2014 05:18 AM, George Kadianakis wrote:
>> Nathan Freitas <nathan@xxxxxxxxxxx> writes:
>>
>>> On May 3, 2014 4:18:28 PM EDT, George Kadianakis <desnacked@xxxxxxxxxx> wrote:
>>>> George Kadianakis <desnacked@xxxxxxxxxx> writes:
>>>>
>>>>> Nathan Freitas <nathan@xxxxxxxxxxx> writes:
>>>>>
>>>>>> On May 3, 2014 6:10:58 AM EDT, George Kadianakis
>>>> <desnacked@xxxxxxxxxx> wrote:
>>>>>>> Nathan Freitas <nathan@xxxxxxxxxxx> writes:
>>>>>>>
>>>>>>>> Orbot now supports Obfs3 and Scramblesuit, thanks to Yawning's
>>>> help.
>>>>>>> Great news! Thanks!
>>>>>>>
>>>>>>> BTW, how are obfs3 bridges supposed to be used?
>>>>>> This is the string I use for scramblesuit, copied directly from the
>>>> bridges.tp.o page:
>>>>>> scramblesuit xxx.xxx.xxx.xxx:xxxxx fingerprintxxx
>>>> password=sharedsecretxxx
>>>>>>> I installed Orbot-v14.0.0-ALPHA-2a.apk and checked the Preferences
>>>>>>> menu. There used to be an option called 'Obfuscated Bridges' that
>>>> it's
>>>>>>> not there anymore. I assumed that I just have to specify a bridge,
>>>> and
>>>>>>> then prefix it with the transport name, like you do in the torrc.
>>>>>> Yes.
>>>>>>
>>>>>>> So I clicked on 'Bridges' and then inserted 'obfs3 <ip>:<port>'
>>>> (with
>>>>>>> my own <ip> and <port>) and started up Orbot. Unfortunately, I think
>>>>>>> that it didn't work very well. In the logs I got:
>>>>>>> """"
>>>>>>> Adding bridge: obfs3 <ip>:<port>
>>>>>> Hmm.... Add a fingerprint perhaps?
>>>>>>
>>>>> Hm, I just tried that bridge again (without adding a fingerprint),
>>>> and
>>>>> now I'm getting the usual PT error:
>>>>> "We were supposed to connect to bridge '<ip>:<port>' using pluggable
>>>>> transport 'obfs3', but we can't find a pluggable transport proxy
>>>>> supporting 'obfs2'. ..."
>>>>>
>>>>> I'm not sure why I'm getting this today instead of the error I was
>>>>> getting yesterday [0]. I don't remember rebooting or changing
>>>>> anything.
>>>>>
>>>>> In any case, this new message usually means that obfsproxy crashed
>>>>> early: before being configured to be a Pluggable Transport. The same
>>>>> should be true for obfsclient too. Could it be a permission issue?
>>>>>
>>>> We played a bit with Yawning on this.
>>>>
>>>> Are we sure that the ClientTransportPlugin is even set at all?
>>>>
>>>> Because looking at
>>>> https://gitweb.torproject.org/orbot.git/blob/HEAD:/src/org/torproject/android/service/TorService.java#l1713
>>>> it seems that it depends on the boolean PREF_BRIDGES_OBFUSCATED which
>>>> apparently is never set since commit 147b57af4.
>>>>
>>>> This seems to agree with my experience since I'm getting the log
>>>> message "Using standard bridges" which is on the 'else' codepath.
>>>>
>>>> Or maybe we are missing something.
>>> Wow, I just realized that I removed that preference UI, but on my test device it was already set to TRUE, since I did not do a clean install.
>>>
>>> Thanks for the testing, and will push a new release our in next 24 hours with that fixed.
>> Thanks!
>>
>> BTW, I'd suggest to parse the Bridge lines to figure out if PTs are
>> used and only then insert a ClientTransportPlugin line (in contrast,
>> to always adding a ClientTransportPlugin line). That's to avoid issues
>> like #11658.
> I am doing that now, by looking for a supported PT type in the bridge
> config lines
>>
>> You can check if a Bridge line uses PTs, by checking if its second
>> element is a C-identifier as the pt-spec.txt suggests. An IP:PORT is
>> not a C-identifier because of the colon.
> That sounds like a better way, especially since PTs could be run outside
> of Orbot as separate apps.
> Here's a new alpha-3 build that has been tested on a few devices, with
> both obfs3 and scramblesuit bridges:
>
> apk: https://guardianproject.info/releases/Orbot-v14.0.0-ALPHA-3.apk
> sig: https://guardianproject.info/releases/Orbot-v14.0.0-ALPHA-3.apk.asc

Works fine in my device using an obfs3 bridge!

Thanks for the rapid fix!

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