- tor-dev - lists.torproject.org

Proposal for Tor (Relay) Watchdog (Telegram) Bot
by Alessandro Greco 29 Apr '24

29 Apr '24

Dear Tor Project Developers, I hope this email finds you well. I am writing to share with you a project [1] I have been working on called Tor Watchdog Bot [2], and I believe it may be of interest to you. Tor Watchdog Bot is a Telegram bot designed to monitor the status of Tor relays and notify users when relays go offline. The intent behind creating this bot was to develop a user-friendly tool that allows anyone to easily keep track of their Tor nodes. I am fully aware that the bot is not currently ready for public release as it requires several bug fixes and improvements. Before proceeding with further development, I wanted to ensure that this project aligns with your interests and goals. In order to prioritize user privacy and security, I did not activate the backend feature with the actual functionality; instead, I activated a demo that always provides the same results but allows users to understand the type of response they would receive if it were active. In the README.md file, you will find detailed instructions on how to set up and test the bot. If you find this project interesting and believe it could be beneficial to the Tor community, I would be delighted to see Tor Project host this service. However, I understand the importance of avoiding any form of user profiling, so I want to ensure that any potential hosting solution prioritizes user privacy. The code for Tor Watchdog Bot is released under the GPLv3 license, so you are libre to use and modify it as you see fit. I would be thrilled to contribute to the development of this project if it aligns with your vision. Thank you for considering this proposal. I look forward to hearing your thoughts and feedback. Best regards, Aleff. [1] https://github.com/aleff-github/TorWatchdog [2] https://t.me/TorWatchdog_bot --- Browse my WebSite: aleff-gitlab.gitlab.io Use my PGP Public Key: pgp.mit.edu/pks/lookup?op=get&search=0x7CFCE404A2168C85 Join to support: - Free Software Foundation! (my.fsf.org/join?referrer=6202114) - Electronic Frontier Foundation! (eff.org) - Tor-Project (torproject.org) - Signal (signal.org)

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Proposal #349: Command state validation (for dropmark attacks)
by Mike Perry 07 Mar '24

07 Mar '24

We've merged a draft of Proposal #349 to torspec: https://gitlab.torproject.org/tpo/core/torspec/-/blob/main/proposals/349-co… Also available on the tor spec site at: https://spec.torproject.org/proposals/349-command-state-validation.html This proposal is meant to deal with the third class of highly severe protocol side channels in tor: Dropped Cells. See Prop #344 for background: https://spec.torproject.org/proposals/344-protocol-info-leaks.html Note that there still are some details that need to be ironed out wrt how and when to perform checks that depend upon full parsing and protocol context, as opposed to just relay message command. This work is part of Sponsor 112; arti-client support is due by EOY 2024. C-Tor will not implement this proposal. -- Mike Perry

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Fact-checking a claim about relay/bridge fingerprint authentication
by David Fifield 25 Feb '24

25 Feb '24

Cecylia, Arlo, Serene, Shelikhoo, and I are writing a research paper about Snowflake. Here is a draft: https://www.bamsoftware.com/papers/snowflake/snowflake.20231003.e6e1c30d.pdf We're writing to check a factual claim in the section about having multiple backend bridges. Basically, we wanted it to be possible for there to be multiple Snowflake bridge sites run by different groups of people, and we did not want to share the same relay identity keys across all bridge sites, because of the increased risk of the keys being exposed. Therefore every bridge site has its own relay identity, which requires the client to know the relay fingerprints in advance and that it be the client (and not, e.g., the broker) that decides which bridge to use. 1. Is our general description (quoted below) of the design constraints as they bear on Tor correct? 2. Is §4.2 "CERTS cells" the right part of tor-spec to cite to make our point? https://gitlab.torproject.org/tpo/core/torspec/-/blob/b345ca044131b2eb18e6a… https://github.com/turfed/snowflake-paper/blob/e6e1c30dde6716dc5e54a32f2134… A Tor bridge is identified by a long-term identity public key. If, on connecting to a bridge, the client finds that the bridge's identity is not the expected one, the client will terminate the connection \cite[\S 4.2]{tor-spec}. The Tor client can configure at most one identity per bridge; there is no way to indicate (with a certificate, for example) that multiple identities should be considered equivalent. This constraint leaves two options: either all Snowflake bridges must share the same cryptographic identity, or else it must be the client that makes the choice of what bridge to use. While the former option is possible to do (by synchronizing identity keys across servers), every added bridge would increase the risk of compromising the all-important identity keys. Our vision was that different bridge sites would run in different locations with their own management teams, and that any compromise of a bridge site should affect that site only. In my own experiments, providing an incorrect relay fingerprint leads to errors in connection_or_client_learned_peer_id: https://gitlab.torproject.org/tpo/core/tor/-/blob/tor-0.4.7.13/src/core/or/… [warn] Tried connecting to router at 192.0.2.3:80 ID=<none> RSA_ID=2B280B23E1107BB62ABFC40DDCC8824814F80A71, but RSA + ed25519 identity keys were not as expected: wanted 1111111111111111111111111111111111111111 + no ed25519 key but got 2B280B23E1107BB62ABFC40DDCC8824814F80A72 + 1zOHpg+FxqQfi/6jDLtCpHHqBTH8gjYmCKXkus1D5Ko. [warn] Problem bootstrapping. Stuck at 14% (handshake): Handshaking with a relay. (Unexpected identity in router certificate; IDENTITY; count 1; recommendation warn; host 1111111111111111111111111111111111111111 at 192.0.2.3:80)

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Re: [tor-dev] UDP Application Support in Tor
by Vilgot Bergquist 13 Feb '24

13 Feb '24

Hi, I looked at the suggested solutions and I think there is another approach, which is much easier. I C it's pretty easy to encapsulate UDP segments inside TCP segments. Hence there is no need to re-organize the connection logic of tor relays. Instead it should be possible to make Guards, when receiving an UDP packet, to just add a TCP header and then it goes through the normal process. The exit nodes than removed the TCP header and pass the UDP segment on. Regards Vilgot tor-dev-request(a)lists.torproject.org <tor-dev-request(a)lists.torproject.org> schrieb am Donnerstag, 25. Januar 2024 um 18:49: > > > Send tor-dev mailing list submissions to > tor-dev(a)lists.torproject.org > > To subscribe or unsubscribe via the World Wide Web, visit > https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-dev > or, via email, send a message with subject or body 'help' to > tor-dev-request(a)lists.torproject.org > > You can reach the person managing the list at > tor-dev-owner(a)lists.torproject.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of tor-dev digest..." > > > Today's Topics: > > 1. New Proposal - UDP Application Support in Tor > (Micah Elizabeth Scott) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 25 Jan 2024 09:49:02 -0800 > From: Micah Elizabeth Scott beth(a)torproject.org > > To: tor-dev(a)lists.torproject.org > Subject: [tor-dev] New Proposal - UDP Application Support in Tor > Message-ID: 79aa2de8-1ff9-4579-b87f-ee9792e9cbb0(a)torproject.org > > Content-Type: text/plain; charset="utf-8"; Format="flowed" > > Hello tor-dev folks! > > Late last year I started taking a close look at what it would take to > support applications on Tor which rely on UDP networking. This was > originally to be based on Nick's proposal, 339-udp-over-tor. > > The scope of this work so far has been specifically focused on end-user > application compatibility, and excludes fundamental changes to Tor's > network structure or protocols for now. > > This combination of approach and scope left me with more questions than > answers, so I started looking deeper into the available solutions along > with their expected benefits and risks. This proposal is the result of > that investigation. > > Please find the text attached, or in the torspec repo as proposal #348: > > https://gitlab.torproject.org/tpo/core/torspec/-/blob/main/proposals/348-ud… > > Unlike a typical proposal, this does not recommend any specific change > to the Tor implementation. Several possible changes are presented, but > ultimately the recommended approach is to use application-specific UDP > relays to achieve compatibility. > > Integrated approaches are also presented, where Tor does involve itself > in the transit of individual datagrams. These approaches offer > advantages only when they are also part of a long-term plan to offer > transport features beyond those offered by TCP. Until such a plan is > in-scope, specific UDP extensions cannot be offered with confidence. > > I would appreciate any feedback on this proposal, whether it's about > this particular shorter-term context or about longer-term plans to > achieve some kind of optional unreliable transport. > > Thanks for your time! > > --beth >

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Announcing Onionspray 1.6.0 with a SECURITY fix for Onion Services rewriting proxies
by rhatto 09 Feb '24

09 Feb '24

Hello everyone, I'd like to announce Onionspray, a tool for setting up Onion Services for existing public websites, working as a HTTPS rewriting proxy: https://tpo.pages.torproject.net/onion-services/onionspray/ It's a fork of Alec Muffett's EOTK (https://github.com/alecmuffett/eotk) with many enhancements but retaining compatibility, and relying on C Tor until an alternative in Arti is available. The first Onionspray version is 1.6.0, following the pre-existing version sequence from EOTK. Security fixes: * This release fixes a CRITICAL security vulnerability related to upstream HTTPS certificate verification, which is detailed at https://tpo.pages.torproject.net/onion-services/onionspray/security/advisor… A related fix is also available for EOTK: https://github.com/alecmuffett/eotk/pull/116 We urge Onionspray users that were testing the software while it was being on it's early stages to upgrade ASAP to 1.6.0 and update their configurations, and we recommend that EOTK to the same with the corresponding patch. This issue might also affect other similar rewriting proxy setups, and we urge operators to review and fix their Onion Service configurations. Main improvements over EOTK: * MetricsPort support (for gathering metrics data from the tor instances). * Denial of Service (DoS) protections. * Circuit ID exporting to NGINX logs and optionally to the upstream proxy (through the X-Onion-CircuitID HTTP header). * Onionbalance v3 support ("softmaps" are working again). * Revamped documentation. * Installation procedures added for recent Debian and Ubuntu releases. * Tor and OpenResty upgraded to the latest versions. * Option to keep Onionspray running in the foreground (`--no-daemonize`). * Local healthcheck action (`--health-local`), useful for containerized execution. The full ChangeLog is available at https://tpo.pages.torproject.net/onion-services/onionspray/changelog/ For those wishing to switch from EOTK to Onionspray, there's a migration guide at https://tpo.pages.torproject.net/onion-services/onionspray/migrating/ We also welcome people to report issues, send merge requests etc: https://tpo.pages.torproject.net/onion-services/onionspray/contact/ And we have a bunch of issues waiting for contributions: https://gitlab.torproject.org/tpo/onion-services/onionspray/-/issues Finally, I'd like to thank Alec Muffett for his important work with EOTK and for promoting Onion Services all these years :) Thanks! -- Silvio Rhatto pronouns he/him

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docker bridge suddenly fails startup with "Directory /var/lib/tor cannot be read: Permission denied"
by gentle.luck4713＠doublequote.org 01 Feb '24

01 Feb '24

Hi tor-dev@, I have been running a bridge following the instructions at <https://community.torproject.org/relay/setup/bridge/docker/> on a Debian 12.4 system but when I just tried to make sure everything is up to date I got the following error message from docker-compose logs: obfs4-bridge_1 | Using NICKNAME=DockerObfs4Bridge, OR_PORT=3845, PT_PORT=443, and EMAIL=redacted(a)example.com. obfs4-bridge_1 | Additional properties from 'OBFS4V_' environment variables processing enabled obfs4-bridge_1 | Overriding 'AddressDisableIPv6' with value '1' obfs4-bridge_1 | Starting tor. obfs4-bridge_1 | Jan 31 22:49:20.501 [notice] Tor 0.4.8.10 running on Linux with Libevent 2.1.12-stable, OpenSSL 3.0.11, Zlib 1.2.13, Liblzma 5.4.1, Libzstd 1.5.4 and Glibc 2.36 as libc. obfs4-bridge_1 | Jan 31 22:49:20.501 [notice] Tor can't help you if you use it wrong! Learn how to be safe at https://support.torproject.org/faq/staying-anonymous/ obfs4-bridge_1 | Jan 31 22:49:20.501 [notice] Read configuration file "/etc/tor/torrc". obfs4-bridge_1 | Jan 31 22:49:20.502 [notice] Based on detected system memory, MaxMemInQueues is set to 6264 MB. You can override this by setting MaxMemInQueues by hand. obfs4-bridge_1 | Jan 31 22:49:20.503 [notice] Opening OR listener on 0.0.0.0:3845 obfs4-bridge_1 | Jan 31 22:49:20.503 [notice] Opened OR listener connection (ready) on 0.0.0.0:3845 obfs4-bridge_1 | Jan 31 22:49:20.503 [notice] Opening OR listener on [::]:3845 obfs4-bridge_1 | Jan 31 22:49:20.503 [notice] Opened OR listener connection (ready) on [::]:3845 obfs4-bridge_1 | Jan 31 22:49:20.503 [notice] Opening Extended OR listener on 127.0.0.1:0 obfs4-bridge_1 | Jan 31 22:49:20.503 [notice] Extended OR listener listening on port 44595. obfs4-bridge_1 | Jan 31 22:49:20.503 [notice] Opened Extended OR listener connection (ready) on 127.0.0.1:44595 obfs4-bridge_1 | Jan 31 22:49:20.504 [warn] Directory /var/lib/tor cannot be read: Permission denied obfs4-bridge_1 | Jan 31 22:49:20.504 [notice] Closing partially-constructed OR listener connection (ready) on 0.0.0.0:3845 obfs4-bridge_1 | Jan 31 22:49:20.504 [notice] Closing partially-constructed OR listener connection (ready) on [::]:3845 obfs4-bridge_1 | Jan 31 22:49:20.504 [notice] Closing partially-constructed Extended OR listener connection (ready) on 127.0.0.1:44595 obfs4-bridge_1 | Jan 31 22:49:20.504 [warn] Failed to parse/validate config: Couldn't create private data directory "/var/lib/tor" obfs4-bridge_1 | Jan 31 22:49:20.504 [err] Reading config failed--see warnings above. I confirmed that my docker-compose.yaml is unmodified and my .env is innocuous. I know that I can blow away the docker volumes but that'd remove the private keys etc. and that'd doesn't seem desirable. Any advice? Thanks, Hein

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New Proposal - UDP Application Support in Tor
by Micah Elizabeth Scott 25 Jan '24

25 Jan '24

Hello tor-dev folks! Late last year I started taking a close look at what it would take to support applications on Tor which rely on UDP networking. This was originally to be based on Nick's proposal, 339-udp-over-tor. The scope of this work so far has been specifically focused on end-user application compatibility, and excludes fundamental changes to Tor's network structure or protocols for now. This combination of approach and scope left me with more questions than answers, so I started looking deeper into the available solutions along with their expected benefits and risks. This proposal is the result of that investigation. Please find the text attached, or in the torspec repo as proposal #348: https://gitlab.torproject.org/tpo/core/torspec/-/blob/main/proposals/348-ud… Unlike a typical proposal, this does not recommend any specific change to the Tor implementation. Several possible changes are presented, but ultimately the recommended approach is to use application-specific UDP relays to achieve compatibility. Integrated approaches are also presented, where Tor does involve itself in the transit of individual datagrams. These approaches offer advantages only when they are also part of a long-term plan to offer transport features beyond those offered by TCP. Until such a plan is in-scope, specific UDP extensions cannot be offered with confidence. I would appreciate any feedback on this proposal, whether it's about this particular shorter-term context or about longer-term plans to achieve some kind of optional unreliable transport. Thanks for your time! --beth

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Timers in Arti?
by Michael Rogers 15 Jan '24

15 Jan '24

Hi, If I understand right, the C implementation of Tor has various state machines that are driven by local libevent timers as well as events from the network. For example, when building a circuit, if there hasn't been any progress for a certain amount of time then a timer fires to handle the timeout. When running Tor on Android, we need to prevent the OS from suspending so that these timers fire when they're supposed to. This uses a lot of battery, because normally the OS would spend most of its time suspended. Unlike a laptop, an Android device with its screen turned off is constantly dipping in an out of suspension, and a lot of the platform's power optimisations are aimed at batching whatever work needs to be done so that the periods of suspension can be longer. If we allowed the OS to suspend then the timers would fire with arbitrary delays, and I don't really know what impact that would have: I'd speculate that there might be connectivity problems (eg dead circuits not being detected and replaced) and/or network-visible changes in the behaviour of circuits that could affect anonymity. So I've had a longstanding but not-very-hopeful request that maybe Tor's reliance on timers could be reduced, or at least clarified, so that we could either allow the OS to suspend without breaking anything, or at least know what was likely to break. And basically I'd just like to renew that request for Arti. Could anyone give me an overview of how these local timers are handled in Arti, or any information about what's likely to happen if the timers are arbitrarily delayed? Thanks, Michael

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txtorcon 23.11.0
by meejah 20 Nov '23

20 Nov '23

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 I'm energized to announce txtorcon 23.11.0 with the following changes: * Fix test-failures on Python 3.12 * Particular GETINFO hanging (https://github.com/meejah/txtorcon/issues/389) (ultra-long lines over 16KiB caused problems in the protocol) * Use built-in `mock` only (https://github.com/jelly) * Remove `incremental` (https://github.com/gdrosos) txtorcon is an implementation of the "control-spec" for Tor using the "Twisted" networking library. This is the library to use if you want to write event-based software (including asyncio; interop is possible) in Python that uses the Tor network as a client or a service (or to integrate Tor support into existing Twisted-using applications). You can download the release from PyPI or GitHub (or of course "pip install txtorcon"): https://pypi.python.org/pypi/txtorcon/23.11.0 https://github.com/meejah/txtorcon/releases/tag/v23.11.0 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 c6c4f5ca5e94ed58be70de0f06d06153b7025cf4c6956b3724194a7cd8736904 dist/txtorcon-23.11.0.tar.gz 59ec801a38d6ea3cedc544cfcdb8e6f180b55d51bf9a01224b09f4bf48262f6b dist/txtorcon-23.11.0-py3-none-any.whl EOF thanks, meejah -----BEGIN PGP SIGNATURE----- iQFFBAEBCgAvFiEEnVor1WiOy4id680/wmAoAxKAaacFAmVbDTcRHG1lZWphaEBt ZWVqYWguY2EACgkQwmAoAxKAaafM/wgA4VdkdG6UgY7XiWQSfrjZZby5sszLJWUa 6T2x4PlHMnI6H2GvspU76n8rHwIfoi5MUIpZvqA17YnN2roPvBZYYwThczh9rhs1 2iTh4geeoBoLJyv8yokfy8gkv0AZ4tdfWa4b3AKA7yqoQ5YSK0hCji+m1jfqyY0q P1FCTDZ2cMl8nQ0/KMxtY1Ifg2tXpQi0OXRujPIHCdqQkA5u94WS1pZZBK3qSNJE 1/20vBI38938wDk/oNapHIeyXYVoVL4DAGq0ADMwYm0syoMZx7NES0a6T3UThKMt szmNj8YR+gwifu3/7UAEZbnAyosSgByqHPaFUu40+Z5LzlXaEnwiaA== =bHsG -----END PGP SIGNATURE-----

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Proposal 347: Domain separation for certificate signing keys
by Nick Mathewson 19 Oct '23

19 Oct '23

To see this rendered, go to https://spec.torproject.org/proposals/347-domain-separation.html ``` Filename: 347-domain-separation.md Title: Domain separation for certificate signing keys Author: Nick Mathewson Created: 19 Oct 2023 Status: Open ``` ## Our goal We'd like to be able to use the "family key" from proposal 321 as a general purpose signing key, to authenticate other things than the membership of a family. For example, we might want to have a challenge/response mechanism where the challenger says, "If you want to log in as the owner of the account corresponding to this family, sign the following challenge with your key. Or we might want to have a message authentication scheme where an operator can sign a message in a way that proves key ownership. We _might_ also like to use relay identity keys or onion service identitiy keys for the same purpose. ## The problem When we're using a signing key for two purposes, it's important to perform some kind of domain separation so that documents signed for one purpose can't be mistaken for documents signed for the other. For example, in the challenge/response example, it would be bad if the challenger could provide a challenge string that would cause the signer to inadvertently authenticate an incorrect family. These keys are currently used in some places with no personalization. Their signature format is as described in `cert-spec.txt`, which says: > The signature is created by signing all the fields in > the certificate up until "SIGNATURE" (that is, signing > sizeof(ed25519_cert) - 64 bytes). ## One solution This one is pretty easy: we would extend `cert-spec` as follows. > ### Using signing keys for other purposes. > > Other protocols may introduce other uses for the signing keys > in these certificates other than those specified here. When > they do, they MUST ensure that the documents being signed > cannot be confused with the certificate bodies of this document. > > In some existing cases in the Tor protocols, we achieve this by > specifying an ASCII prefix string that must be prepended to the > other protocol's signed object before it is signed. > > For future protocols, we recommend that this be done by > specifying that the signing key is to be used to sign a > cSHAKE digest (or other secure customizable digest) > of the other protocol's signed object, using > a customization string unique to the other protocol. We would also make this amendment: > ### Future versions of this specification > > In order to maintain the domain separation that currently exists > between the signatures on these certificates and other documents > signed with the same keys, it suffices (for now!) that these > certificates begin with the version byte `[01]`, whereas > the other documents are in printable ASCII, which never > includes `[01]`. > > Future versions of this specification SHOULD move to using > an ed25519-prehash construction, using a customizable hash > with built-in domain separation.

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