tor-dev March 2022

tor-dev@lists.torproject.org

9 participants
8 discussions

Two features that would help load-balanced bridges
by David Fifield 01 Jun '23

01 Jun '23

After the blocking of Tor in Russia in December 2022, the number of Snowflake users rapidly increased. Eventually the tor process became the limiting factor for performance, using all of one CPU core. In a thread on tor-relays, we worked out a design where we run multiple instances of tor on the same host, all with the same identity keys, in order to effectively use all the server's CPU resources. It's running on the live bridge now, and as a result the bridge's bandwidth use has roughly doubled. Design thread https://forum.torproject.net/t/tor-relays-how-to-reduce-tor-cpu-load-on-a-s… Installation instructions https://gitlab.torproject.org/tpo/anti-censorship/team/-/wikis/Survival-Gui… Two details came up that are awkward to deal with. We have workaround for them, but they could benefit from support from core tor. They are: 1. Provide a way to disable onion key rotation, or configure a custom onion key. 2. Provide a way to set a specific authentication cookie for ExtORPort SAFE_COOKIE authentication, or a new authentication type that doesn't require credentials that change whenever tor is restarted. I should mention that, apart from the load-balancing design we settled on, we have brainstormed some other options for scaling the Snowflake bridge or bridges. At this point, none of these ideas can immediately be put into practice, because there's no way to tell tor "connect to one of these bridges at random, but only one," or "connect to this bridge, but accept any of these fingerprints." https://bugs.torproject.org/tpo/anti-censorship/pluggable-transports/snowfl… # Disable onion key rotation Multiple tor instances with the same identity keys will work fine for the first 5 weeks (onion-key-rotation-days + onion-key-grace-period-days), but after that time the instances will have independently rotated their onion keys, and clients will have connection failures unless the load balancer happens to connect them to the instance whose descriptor they have cached. This post investigates what the failure looks like: https://lists.torproject.org/pipermail/tor-relays/2022-January/020238.html Examples of what could work here are a torrc option to set onion-key-rotation-days to a large value, an option to disable onion key rotation, an option to set a certain named file as the onion key. What we are doing now is a bit of a nasty hack: we create a directory named secret_onion_key.old, so that a failed replace_file causes an early exit from rotate_onion_key. https://gitweb.torproject.org/tor.git/tree/src/feature/relay/router.c?h=tor… There are a few apparently benign side effects, like tor trying to rebuild its descriptor every hour, but it's effective at stopping onion key rotation. https://lists.torproject.org/pipermail/tor-relays/2022-January/020277.html # Stable ExtORPort authentication ExtORPort (extended ORPort) is a protocol that lets a pluggable transport attach transport and client IP metadata to a connection, for metrics purposes. In order to connect to the ExtORPort, the pluggable transport needs to authenticate using a scheme like ControlPort authentication. https://gitweb.torproject.org/torspec.git/tree/proposals/217-ext-orport-aut… tor generates a secret auth cookie and stores it in a file. When the pluggable transport process is managed by tor, tor tells the pluggable transport where to find the file by setting the TOR_PT_AUTH_COOKIE_FILE environment variable. In the load-balanced configuration, the pluggable transport server (snowflake-server) is not run and managed by tor. It is an independent daemon, so it doesn't have access to TOR_PT_AUTH_COOKIE_FILE (which anyway would be a different path for every tor instance). The bigger problem is that tor regenerates the auth cookie and rewrites the file on every restart. All the tor instances have different cookies, and snowflake-server does not know which it will get through the load balancer, so it doesn't know what cookie to use. Examples of what would work here are an option to use a certain file as the auth cookie, an option to leave the auth cookie file alone if it already exists, or a new ExtORPort authentication type that can use the same credentials across multiple instances. What we're doing now is using a shim program, extor-static-cookie, which presents an ExtORPort interface with a static auth cookie for snowflake-server to authenticate with, then re-authenticates to the ExtORPort of its respective instance of tor, using that instance's auth cookie. https://lists.torproject.org/pipermail/tor-relays/2022-January/020183.html

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Interoperation with libp2p
by Mike Mestnik 07 Apr '22

07 Apr '22

https://gitlab.torproject.org/tpo/core/torspec/-/issues/64

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[dappy] Willing to chat with tor devs, about name system issues/solutions
by Raphaël Fabre 27 Mar '22

27 Mar '22

Hello I'm Raphaël (fr) I just joined the tor dev mailing list. I would like to chat with tor developers, particularly if they have worked, or are interested in the issues regarding a name system for tor. I'm the lead developer of dappy https://dappy.tech , we'll launch in 2022 and I do think we have interesting properties, for the public web as well as for tor and privacy-focused web projects. We are the only name system in the world that does co-resolution, that's the way we found to maintain a consistent name system, and also avoid censorship and phishing. Our system has the following properties: - blockchain-based name system: it simply means that mapping is globally consistent, name management is distributed in the sense that a blockchain handles it, the resolver just connect to this blockchain. - Systematic co-resolution (not rotation): lookup request are always addressed to a network of independant agents: there are many instead of a single one. And then there is consensus at browser level. This prevents 90% of attacks or attempt of censorship/phishing. - Anonymous registrations - Load-balancing of names: you can attach 20 IP addresses to your name, dappy browser will try each one of them until it gets a response. - 100% encrypted/https Censorship cannot happen, neither at the storage location (blockchain) or on-the-fly at resolution time (co-resolution) We will launch in 2022 and would be thrilled to exchange with some developers or engineers. This document has lead me to the path of the tor-dev mailing list https://gitlab.torproject.org/legacy/trac/-/wikis/doc/OnionServiceNamingSys… Happy to chat Merry Christmas Raphaël Fabre Building a ultra-secure blockchain-based name system and browser https://dappy.tech

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Time interval for changing Introduction Points in Tor Hidden Services
by Piyush Kumar Sharma 23 Mar '22

23 Mar '22

Hi all, I have been investigating the Tor hidden services for some research work. I am finding it hard to obtain information about how often do Introduction Points of hidden service change. More specifically, I am looking for answers to the following questions: 1.) If the tor relays selected as Introduction Points for a hidden service go down (e.g., due to DoS), then in what time duration does the hidden service select new Introduction Points automatically? 2.) Even when the Introduction Points are not down, is there a duration after which they are automatically changed by the hidden service? If so, what is this duration? I have already tried to find this information in the Tor-spec about onion v3 services. But could not find answers to these specific questions. Thus, it would be really helpful if someone can answer these questions or point to some resources where this information can be obtained. Thanks

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Gosling onion-to-onion specifications
by Richard Pospesel 19 Mar '22

19 Mar '22

Hi tor-dev, As part of my work with Blueprint for Free Speech, I recently gave a short presentation during the 2021 state-of-the-onion where we announced Gosling ( see https://youtu.be/mNhIjtXuVzk?t=8155 ). If you missed the talk, the tldr; is that we're developing a specification and reference implementation library for building (onion service based) anonymous+private+secure peer-to-peer applications. Essentially, we're taking what we've learned about onion-to-onion authentication from Ricochet-Refresh, extracting and improving the relevant pieces, and packaging it all in a library that developers can use to build their own anonymous+private+secure peer-to-peer applications. Our hope is that future developers will not need to be tor experts to build these types of applications. Today ,I'm happy to announce that we just made the the gosling repo on Github public! - https://github.com/blueprint-freespeech/gosling Things are little bare-bones at the moment, but the most relevant piece right now is the protocol specification here: - https://github.com/blueprint-freespeech/gosling/blob/main/docs/protocol.md You'll also find some initial prototyping work under the source directory (the pace of development should pick up come 2022). Please go take a look and feel free to respond here with any questions, concerns, criticisms, etc. Thanks! best, -Richard

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txtorcon v22.0.0
by meejah 16 Mar '22

16 Mar '22

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 I'm pleased to announce txtorcon 22.0.0. This fixes some broken infrastructure. * Use GitHub Actions (not Travis) * Update method to upload coverage to coveralls You can download the release from PyPI or GitHub (or of course "pip install txtorcon"): https://pypi.python.org/pypi/txtorcon/22.0.0 https://github.com/meejah/txtorcon/releases/tag/v22.0.0 Releases are also available from the hidden service: http://fjblvrw2jrxnhtg67qpbzi45r7ofojaoo3orzykesly2j3c2m3htapid.onion/txtor… http://fjblvrw2jrxnhtg67qpbzi45r7ofojaoo3orzykesly2j3c2m3htapid.onion/txtor… You can verify the sha256sum of both by running the following 4 lines in a shell wherever you have the files downloaded: cat <<EOF | sha256sum --check 89a1b65e32a4b369d67e6c166387fbc468cc5d05227448d239a5e7e9718aa053 dist/txtorcon-22.0.0.tar.gz 824b5df1977bedabfc1c49c9523b8fa1b7cff11d6fee78015df1ce133685779c dist/txtorcon-22.0.0-py2.py3-none-any.whl EOF thanks, meejah -----BEGIN PGP SIGNATURE----- iQFFBAEBCgAvFiEEnVor1WiOy4id680/wmAoAxKAaacFAmIyVzMRHG1lZWphaEBt ZWVqYWguY2EACgkQwmAoAxKAaaeNYQf/XBYfAvqqvT/jU+z8EUwgj0EJbFusNAls 8W37RE8fRkxTCYBOnfmK2IlQouHLBVgjzS2H0ZGyAzczxZb/kfY7uRbAm7N63eMx rc7urZtDeHS4K7+cUPf03KlqYdKmbIGEezPVQSNRT1/UZ/kTB6CxMqteyXxfYkvY +pkfIvOJ49Yw6KuMt+iWKRNnfVsMNYX+gV6PNYBHoWGRTWxANReaXRSowe+5Cgus 4O51I3+1QH1slLIH77Dvpktmqka+Fbs3mDWm1ICzf4rB0z+aJRxt7xYjNnhaLCPQ 5xeY1IdmmJAxg/WouMQh1Kus8eEWgIhFLeigPN+ABwt2VziL1lL8XQ== =HKmX -----END PGP SIGNATURE-----

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Proposal 338: Use an 8-byte handshake in NETINFO cells
by Nick Mathewson 14 Mar '22

14 Mar '22

``` Filename: 338-netinfo-y2038.md Title: Use an 8-byte timestamp in NETINFO cells Author: Nick Mathewson Created: 2022-03-14 Status: Open ``` # Introduction Currently Tor relays use a 4-byte timestamp (in seconds since the Unix epoch) in their NETINFO cells. Notoriously, such a timestamp will overflow on 19 January 2038. Let's get ahead of the problem and squash this issue now, by expanding the timestamp to 8 bytes. (8 bytes worth of seconds will be long enough to outlast the Earth's sun.) # Proposed change I propose adding a new link protocol version. (The next one in sequence, as of this writing, is version 6.) I propose that we change the text of tor-spec section 4.5 from: ``` TIME (Timestamp) [4 bytes] ``` to ``` TIME (Timestamp) [4 or 8 bytes *] ``` and specify that this field is 4 bytes wide on link protocols 1-5, but 8 bytes wide on link protocols 6 and beyond. # Rejected alternatives Our protocol specifies that parties MUST ignore extra data at the end of cells. Therefore we _could_ add additional data at the end of the NETINFO cell, and use that to store the high 4 bytes of the timestamp without having to increase the link protocol version number. I propose that we don't do that: it's ugly. As another alternative, we could declare that parties must interpret the timestamp such that its high 4 bytes place it as close as possible to their current time. I'm rejecting this kludge because it would give confusing results in the too-common case where clients have their clocks mis-set to Jan 1, 1970. # Impacts on our implementations Arti won't be able to implement this change until it supports connection padding (as required by link protocol 5), which is currently planned for the next Arti milestone (1.0.0, scheduled for this fall). If we think that that's a problem, or if we want to have support for implementations without connection padding in the future, we should reconsider this plan so that connection padding support is independent from 8-byte timestamps. # Other timestamps in Tor I've done a cursory search of our protocols to see if we have any other instances of the Y2038 problem. There is a 4-byte timestamp in `cert-spec`, but that one is an unsigned integer counting _hours_ since the Unix epoch, which will keep it from wrapping around till 478756 C.E. (The rollover date of "10136 CE" reported in `cert-spec` is wrong, and seems to be based on the misapprehension that the counter is in *minutes*.) The v2 onion service protocol has 4-byte timestamps, but it is thoroughly deprecated and unsupported. I couldn't find any other 4-byte timestamps, but that is no guarantee: others should look for them too.

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Fine Tunneling For Tor Network | Tor Browser
by Alessandro Greco 09 Mar '22

09 Mar '22

Dear Tor-Dev, My name is Alessandro Greco and I am an Italian computer science student, I am finishing my studies and therefore I am working with my thesis and, as a topic, my supervisor and I have chosen the Tor network. The work done focuses entirely on the Tor Browser torrc configuration file, which is why I wrote Professor Steven Murdoch and he pointed me to this method in order to get in touch with the current Tor-Project developers. I state that I am not good in English and therefore I may be wrong or not give the right weight to the words. Going into the matter, I have developed an extension currently available only on Firefox reachable via the addresshttps://addons.mozilla.org/it/firefox/addon/tropea-project/. The initial goal was to simplify the tunneling phase, already editable through the Tor Browser torrc file, through commands such as ExitNode or ExcludeNode and much more. In order to simplify the use, I decided to create an extension and an "advanced" section, thus bringing back user-friendly graphic interfaces already well known to average users (the advanced section consists of a web page), which would allow modify the file to your liking without necessarily having to follow correct syntax and without having to go too far into the technical aspect of Tor Browser. Why? I decided to simplify the use of this configuration file because I believe that the path of "simplification" is the only (or in general one of the most important) way to be able to expand the catchment area by trying to accommodate more people who have the need for a network like Tor in order to be able to divert dictatorial censorship methods by governments. I want to give a practical example, let's consider the current situation between Russia and Ukraine. Although Putin belongs to Russia, it is also true that there is a large slice of Russian citizens who are intellectually suppressed every day given the limits of censorship by the Russian government and by other governments that limit the people in order to weaken Putin. Russia has currently blocked several social networks so that citizens can no longer share the atrocities that are happening, so much so that Anonymous has asked to publish photos and videos of what is happening through Google Maps or other applications that are currently not censored. In all this mess, I sincerely think that Tor can significantly affect the protection of truth and rights on the net. But it is also true that many people do not know how to use or modify these settings correctly or, more simply, they may not even know that they can change some settings. I strongly believe that a breakthrough in the world of Tor Networks is needed and so that citizens of every state in the world can have, without minimum IT requirements, the ability to fully use Tor Browser and consequently Tor. The thesis work is called Tropea-Project (Tropea is a type of onion from our area, if you want to do a search, look for Tropea Onion on Google) and it is completely free and open-source so that anyone can dare to add new features. The features currently available are the following: [Add-Remove] EntryNodes + StrictNodes [Add-Remove] ExitNodes + StrictNodes [Add-Remove] ExcludeNodes [Add-Remove] ExcludeExitNodes [Edit] GeoIPExcludeUnknow [Edit] Reset configuration [Torify App] Torify /*It depends on the application launched, [Working Application](https://github.com/NoNameoN-A/Tropea-Project/blob/main)*/ Please consider this project, at the moment I am struggling with the writing of the thesis so in a few weeks an extremely detailed guide on the whole programming aspect will be published so that I can help any student, programmer, hacker and anyone who wants to improve existing features or add new ones. I am very excited to write you this email and I hope you can consider this development of mine which focuses 100% of the forces so that the Tor project can help free as many people as possible from inhuman web slavery. I believe that online freedom is a humanitarian right on par with education and water, so I think it is appropriate to develop new features that simplify its use. If you have read this far I would ask you now to see the demonstration video that I have published so that you can see for yourself what it does and I hope you can understand how much I care. Now more than ever anyone needs Tor. * Technical notes on the extension * In order for it to be used correctly, you must first start a local script called tropea.js, which is located in the socket-tropea folder of the Repository. The extension code is in the tropea folder of the Repository. Since the exact path of the Tor Browser folder is required, due to the configuration of the torrc file, it would be ideal to install it when installing Tor Browser so as to further simplify the whole process so that they don't even have to run the local script as it might launch when Tor Browser starts. Repository:https://github.com/NoNameoN-A/Tropea-Project Demonstration video:https://peertube.uno/w/acz9VzntwYFicwgxk7i9by I wrote an informal article on my blog:https://greco-alessandro.netlify.app/articles/tropea-project-la-rete-tor-da-un-altro-punto-di-vista/ Thesis with technical documentation of the code: At the moment not available because I haven't finished writing it yet. Best Regards, Alessandro Greco. -- FSF Member (NoNameoN), Join the Free Software Foundation! (fsf.org), Browse my WebSite! (autistici.org/nonameon)

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tor-dev March 2022