[tor-onions] Onion-routing of The Free Software Foundation Europe

[Hiro/Silvia]

Hi Jacob,

On 2021-01-26 20:14, Jacob Hrbek wrote:
> On 1/23/21 8:59 PM, Silvia Puglisi, Ph.D. wrote:
>> Hi Jacob,
>>
>> On 2021-01-22 12:21, Jacob Hrbek wrote:
>>> On 1/21/21 9:27 PM, Silvia wrote:
>>>> Exciting to see fsfe moving to onions.
>>>> How can we help you guys with this?
>>> Currently the main problem is with implementation as there is an issue
>>> with certificates using TLS-over-onions (Not economical for non-profit
>>> foundation) where it seems that using reverse proxy with currently used
>>> Apache or implementing EOTK is the way to go there?
>>
>> Yes EOTK uses a TLS certificate. The idea behind this is that if the
>> certificate belongs to fsfe, visitors of the onion service can be sure
>> that the onion has been setup by fsfe.
>> The certificate is not needed for any other reason than that.
>>
>> If you are concerned about how people discover your onion you can use
>> the onion-location header so that people visting fsfe.org over tor get
>> the onion available button on the url bar and can get redirected to the
>> onion
>> (https://community.torproject.org/onion-services/advanced/onion-location/).
>>
>>> More options and way
>>> to configure EOTK (alec seems to be currently busy and unable to answer)
>>> appreciated.
>> EOTK is a tool that setup a few options for you in nginx and install
>> required packages, but you can setup the onion also manually.
>>
>> Here for example you will find a gist of the nginx config of the
>> propubblica onion:
>> https://gist.github.com/mtigas/9a7425dfdacda15790b2
>>
>>> Also brainstorm for the implementation as a whole would be appreciated
>>> the services seems to be mostly running in jail/VM which is favorable to
>>> be preserved for security reasons (e.g. in scenario where there is a
>>> major bug discovered in the wild to reduce the impact of one service on
>>> the system).
>>> So i am currently unsure whether we want to:
>>> 1. run one tor daemon per system in jail/VM to provide the routing from
>>> exposed ports from the services e.g.
>>> https://git.fsfe.org/kreyren/fsfe-planet/src/branch/onionz/docker-compose.yml
>>> 2. implementing tor daemon within these jails/VMs with the service
>>>
>>> srv/service1 (exposing port 12447)
>>> srv/service2 (exposing port 12448)
>>>
>>> and setting tor as
>>>
>>> HiddenServiceDir /var/lib/tor/service1
>>> HiddenServicePort 12447 127.0.0.1:12447
>>>
>>> HiddenServiceDir /var/lib/tor/service2
>>> HiddenServicePort 12447 127.0.0.1:12447
>>>
>>>
>> I am not sure about the exact architecture here, but generally you need
>> a master onion where you run onion balance and use it to scale
>> horizontally with different backends
>> (https://onionbalance-v3.readthedocs.io/en/latest/v3/tutorial-v3.html).
>>
>> If you are concerned about DOS attacks you can also implement some more
>> advanced web server configs.
>> One of them is using captchas, another is to use cookies to filter out
>> scripted clients. The idea in this case is that the web server sends the
>> client a cookie and ask the client to verify it. Usually scripted
>> clients don't set cookies so the verify fails and you find out that the
>> client is malicious.
>>
>> Nginx uses openresty and lua to implement captchas. This solution is
>> usually highly scripted. With regards to cookies I can recommend this
>> library from cloudflare for openresty
>> https://github.com/cloudflare/lua-resty-cookie. I am sure there are
>> equivalent solution in apache.
>>
>>
>>> 3. implementing tor daemon on the router assuming all services being
>>> routed through a routing server, but i am concerned about sanitization
>>> as if there is a bug in tor that could expose user traffic to bad
>>> actors. (currently being discussed)
>>>
>>> 4. Implementing xen (https://en.wikipedia.org/wiki/Xen) which currently
>>> not favorable as it would require lots of work on the backend.
>>>
>>> 5. Other?
>> There is a tool called onionscan (https://onionscan.org/) that can help
>> you find vulnerabilities on your onion. This also test things like bugs
>> in your web service that might expose users data and information that
>> you might prefer to keep secure.
>>
>> I also assume that the fsfe onion isn't interested to be anonymous so
>> you might consider setting up a 1-hop onion in this case
>> (https://support.torproject.org/glossary/single-onion-service/).
>>
>> Let me know if you need more help.
>>
>> Cheers,
>> -hiro
>>> FWIW i would also like to provide something like
>>> https://onion.debian.org so that the website list is available to the
>>> end-user.
>>>
>>>
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> 
> I am sorry for delay had to process lots of informations.
> 
> The onion-location HTTP header is already tracked.
> 
> Added propublica configuration in tracking as example configuration, thanks!
> 
> One-hop non-anonymous onion service noted in tracking.
> 
> OnionScan noted in tracking and recommended to be adapted as Continuous 
> Integration.
> 
> Personal tracking updated in 
> https://github.com/Kreyren/kreyren/issues/60 peer-review appreciated.
> 
> About the (D)DoS -> i was told that they are not a concern over onion 
> routing due to the hard delay used for encryption. Can you confirm?
> Overall the (D)DoS is part of a threat model as FSFE has been (D)DoSed 
> in the past where the main concern is Gitea as the static pages require 
> an unreasonable amount of resources to be taken down atm.

So onion service DoS is a bit different than normal DoS, because the
target in this case is the tor daemon. So while the website will still
be reached on the normal internet in the case of onion service DoS it
will be the onion that will not be reached.

Check out this blog post to have a better idea:
https://blog.torproject.org/stop-the-onion-denial

> 
> About Apache -> This is currently used by the webserver and needs to be 
> implemented with priority in 
> https://git.fsfe.org/fsfe-system-hackers/webserver-bunsen/src/branch/master/files/apache2-sites
> (currently tracked in 
> https://git.fsfe.org/fsfe-system-hackers/webserver-bunsen/pulls/7). Any 
> relevant information to the implementation is appreciated as i am 
> currently struggling with making the TLS-over-onion work there where 
> apache should strip the TLS when the website is accessed over onions. 
> Any relevant information appreciated.

I am not particularly familiar with the specific Apache syntax but why
do you want to strip the TLS?
Can't you just specify a different configuration for the onion in Apache
where TLS is not used? Like a different VirtualHost that use port 80 for
the onion?

> 
> About Nginx -> Currently not an option as the website is already using 
> Apache.
> 
> About EOTK -> I would like to implement this as an alternative 
> configuration for system hackers to have a choice and do their research 
> more efficiently and I assume that being a better implementation here as 
> we currently want to onionize gitea service which based on my experience 
> on https://git.dotya.ml requires changing of non-relative links within 
> the webapp (which can be done in nginx/apache, but seems to be painful 
> to maintain?).

What do you mean alternative configuration? 

We are also working on a library of scripts for different configuration
systems. For example:
https://gitlab.torproject.org/hiro/terraform-onions for terraform.


> 
> FWIW i am also considering decentralization for the static pages where 
> the theory is to reduce the system load, make the websites less 
> vulnerable to (D)DoS and make the websites to load faster as the 
> webserver would be closer to the client in question. I am not aware of 
> sane configuration for this over onions, but any relevant info appreciated.
> 

Do you mean serving the static pages from different mirrors?
I think in this case you might want to consider using a v3 onionbalance
master onion and implement a few fronts and then add all their onion
addresses to onionbalance's configuration and run it. If DoS over onion
is a big concern for you I think running 2/3 fronts is a good idea.

Let me know if this helps.

Cheers,
-hiro

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