[tor-relays] We need much more bridges with obfs4 and iat-mode set to 1 or 2..barely can't find any.

Fran fatal at mailbox.org
Wed Aug 24 10:51:25 UTC 2022


Philipp Winter regarding iat mode:

 >The feature introduces a substantial performance penalty for a dubious
 >and poorly understood privacy gain.  If I were to write an algorithm to
 >detect obfs4, I wouldn't bother dealing with its flow properties; there
 >are easier ways to identify the protocol.  In hindsight, it was >probably
 >a mistake to expose the iat option to users and bridge operators.
 >
 >Cheers,
 >Philipp

https://lists.torproject.org/pipermail/tor-relays/2021-February/019370.html

On 8/24/22 09:50, John Csuti via tor-relays wrote:
> I can dedicate 2 more IP’s from my network to this. You just want it to 
> be obfs4 and iat-mode set to 2?
> 
> Thanks,
> John C.
> 
>> On Aug 24, 2022, at 2:35 AM, elise.toradin at web.de wrote:
>>
>> 
>> As in the title, it took me over an hour to find one - for my security 
>> requirements, the timing and sometimes, packet size obfuscation, is 
>> very important.
>> Now this might sound a bit like sarcasm, but I also think that we 
>> should harden the https://bridges.torproject.org page, just a captcha 
>> and not delivering new bridges to the same IP is a bit weak, in my 
>> opinion.
>> Perhaps extend that block to an entire /16 range, or require some 
>> computational power to be used up (could be easily implemented in 
>> JavaScript) first.
>> The last suggestion would also eliminate bots that scrape bridge 
>> addresses using plaintext clients entirely, at least until someone 
>> builds a chromium / (insert arbitrary browser engine here) bot.
>> I know this is a cat and mouse game, but the bridge page should be as 
>> secure as possible.
>> For example: I wouldn't mind waiting 5-15 minutes to get a list of 3 
>> bridges (optionally, with a button that says, iat-mode non-zero only, 
>> but we need to harden more before implementing something like that), 
>> some government agencies might be thrown off by this, along with the 
>> fact that they also only have limited IP ranges.
>> Thoughts?
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> 
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