Hey everyone! Here are our meeting logs: http://meetbot.debian.net/tor-meeting/2025/tor-meeting.2025-10-02-16.00.html And our meeting pad: Anti-censorship work meeting pad -------------------------------- Anti-censorship -------------------------------- Next meeting: Thursday, October 9 16:00 UTC Facilitator:meskio ^^^(See Facilitator Queue at tail) Weekly meetings, every Thursday at 16:00 UTC, in #tor-meeting at OFTC (channel is logged while meetings are in progress) This week's Facilitator: shelikhoo == Goal of this meeting == Weekly check-in about the status of anti-censorship work at Tor. Coordinate collaboration between people/teams on anti-censorship at the Tor Project and Tor community. == Links to Useful documents ==     * Our anti-censorship roadmap:         * Roadmap:https://gitlab.torproject.org/groups/tpo/anti-censorship/-/boards     * The anti-censorship team's wiki page:         * https://gitlab.torproject.org/tpo/anti-censorship/team/-/wikis/home     * Past meeting notes can be found at:         * https://lists.torproject.org/pipermail/tor-project/     * Tickets that need reviews: from projects, we are working on:         * All needs review tickets:             * https://gitlab.torproject.org/groups/tpo/anti-censorship/-/merge_requests?sc...         * Project 158 <-- meskio working on it             * https://gitlab.torproject.org/groups/tpo/anti-censorship/-/issues/?label_nam... == Announcements == == Discussion ==     * Reported blocking of www.cdn77.com by SNI, blocking of STUN servers in Russia, 2025-09-21         * https://github.com/net4people/bbs/issues/422#issuecomment-3316062302         * "I've noticed that stun protocol was blocked from mid-summer till today (it worked in June last time when I've used public stun to punch through NAT). Seems that only stun to public stun servers like stun.l.google.com, stun.bethesda.net were affected. Stun between webtunnel client and other webtunnel peer is not affected as can be seen in attached captures below. The only stun server that was accessible all that time was stun.rtc.yandex.net (of all the gists and lists of public stun servers I could find)."         * "Had to change front though ... where <...> is another website using cdn77 I know. www.cdn77.com is blocked by SNI (session freezes after client hello), and www.phpmyadmin.net, though it doesn't cause hetzner to be blocked anymore, might cause stricter filtering or other side-effects."         * We've been testing netlify in the alpha channel of Tor Browser, maybe it is time to use it in stable.         * cdn77 domain fronts are already known to be blocked in China             * https://gitlab.torproject.org/tpo/anti-censorship/team/-/issues/168         * meskio has a list of cdn77 domain names.             * https://gitlab.torproject.org/tpo/anti-censorship/team/-/issues/168#note_326...         * Could prioritize adding multiple builting snowflake bridge options             * https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/43842         * onyinyang will make a forum post with workarounds == Actions ==     * Remove webtunnel setuid script in 2 weeks.(decrease this by one every week) == Interesting links ==     * https://github.com/net4people/bbs/issues/422#issuecomment-3316062302 (2025-09-21)         * (Russia) "I've noticed that stun protocol was blocked from mid-summer till today (it worked in June last time when I've used public stun to punch through NAT). Seems that only stun to public stun servers like stun.l.google.com, stun.bethesda.net were affected. Stun between webtunnel client and other webtunnel peer is not affected as can be seen in attached captures below. The only stun server that was accessible all that time was stun.rtc.yandex.net (of all the gists and lists of public stun servers I could find)."         * "<...> is another website using cdn77 I know. www.cdn77.com is blocked by SNI (session freezes after client hello), and www.phpmyadmin.net, though it doesn't cause hetzner to be blocked anymore, might cause stricter filtering or other side-effects."     * Mention of snowflake SNIs in the galaxy/platform/galaxy-qgw-service repo of MESA Git. The filenames include "E21" which is Ethiopia.         * https://geedge-git.haruue.com/mesalab_git/galaxy/platform/galaxy-qgw-service...         E21-SNI-Top120W-20221020.txt             snowflake-broker.freehaven.net    903971    110             snowflake-broker.torproject.net    8667377    55             snowflake-broker.bamsoftware.com    1611029    49             snowflake.torproject.net    105990565    16             snowflake.freehaven.net    24545    6         E21-SNI-Top200w.txt             snowflake-broker.bamsoftware.com    14468             snowflake-broker.torproject.net    50             snowflake.bamsoftware.com    8         * https://geedge-git.haruue.com/mesalab_git/galaxy/platform/galaxy-qgw-service...             * "Galaxy SQL, the unified query gateway, is built with Spring Boot 2.0 technology. It provides interactive SQL analysis and routine scheduling windows, supports streaming and batch jobs, and makes it easier to write and submit ETL programs and efficiently execute big data computations, aiming to make big data processing easier."     * Mention of torproject.net domain names in tango/maat/test/tsgrule/TSG_OBJ_FQDN.E21. TSG is Tiangou Secure Gateway, E21 is Ethiopia, Maat is a rules matching engine.         * https://geedge-git.haruue.com/mesalab_git/tango/maat.git/tree/test/tsgrule?h...         592177551    151465    .snowflake-broker.torproject.net 0    1    0    1    1683275236000000 0    key=592177551         592561443    151465    .snowflake.torproject.net    0 1    0    1    1683275236000000 0    key=592561443         592691531    151465    .forum.torproject.net    0    1 0    1    1683275236000000 0    key=592691531         594169529    151469    snowflake-broker.torproject.net 0    3    0    1    1683276253000000 0    key=594169529         594553421    151469    snowflake.torproject.net    0 3    0    1    1683276253000000 0    key=594553421         594683509    151469    forum.torproject.net    0    3 0    1    1683276253000000 0    key=594683509         * You can decode the microsecond timestamps like so:         $ date -u --iso=sec --date=@1683275236         2023-05-05T08:27:16+00:00     * https://filter.watch/english/2025/10/02/irans-stealth-blackout-a-multi-stake...         * https://filter.watch/wp-content/uploads/sites/2/2025/10/Click-here-to-read-t...         * Discussion of Tor starting on PDF page 23 == Reading group ==     * We will discuss "The Internet Coup" on October 23rd         * https://interseclab.org/wp-content/uploads/2025/09/The-Internet-Coup_Septemb...         * Particularly relevant sections: "Blocking online privacy and circumvention tools" section of InterSecLab report on Geedge Networks, mentions Tor, Snowflake, WebTunnel         * Notes: https://github.com/net4people/bbs/issues/519#issuecomment-3282101626         * Questions to ask and goals to have:             * What aspects of the paper are questionable?             * Are there immediate actions we can take based on this work?             * Are there long-term actions we can take based on this work?             * Is there future work that we want to call out in hopes that others will pick it up? == Updates == Name:         This week:             - What you worked on this week.         Next week:             - What you are planning to work on next week.         Help with:             - Something you need help with. cecylia (cohosh): 2025-10-02     Last week:         - wrote up a roadmap for researching snowflake enumeration attacks (snowflake#40396)         - helped debug email bridge distributor (rdsys#129)         - reviewed update to telegram bridge distributor (rdsys!589)         - removed some legacy code from snowflake-webext and fixed minor bugs (snowflake-webext#121)     Next week:         - research snowflake enumeration attacks (snowflake#40396)         - follow up on snowflake rendezvous failures (snowflake#40447)         - take a look at potential snowflake orbot bug             - https://github.com/guardianproject/orbot-android/issues/1183 dcf: 2025-10-02     Last week:     Next week:         - open issue to have snowflake-client log whenever KCPInErrors is nonzero https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowf...             - parent: https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowf... Help with: meskio: 2024-10-02     Last week:         - be AFK         - catch up     Next week: Shelikhoo: 2024-10-02     Last Week:          - [Testing] Unreliable+unordered WebRTC data channel transport for Snowflake rev2 (cont.)( https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowf... ) testing environment setup/research          - Published Snowflake UDP mode test post: https://forum.torproject.org/t/invitation-to-test-snowflake-unreliable-trans...             - vantage point maintaince     Next (working) Week/TODO:         - Merge request reviews         - [Deployment]Unreliable+unordered WebRTC data channel transport for Snowflake rev2 (cont.)( https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowf... ) Building custom Tor Browser with patch applied         - deploy new vantage point version with fixed performance onyinyang: 2025-10-02     Last week(s):         - Deployed updated telegram distributor distributing a proportion of webtunnel bridges to telegram users with new accounts https://gitlab.torproject.org/tpo/anti-censorship/rdsys/-/issues/283         - Managed some hiccups in the updated deployment         - Wrote profiling patch for rdsys: kraken and email         - Looked into conjure issue from China: fronts we are using appear to be blocked Next week:      - Troubleshoot conjure not connecting in China      - Finish up debugging rdsys#129 and rdsys#249 hopefully         - Continue looking into bridgestrap#47         - Lox still seems to be filling up the disk on the rdsys-test server despite changes made to delete old entries, look into what's going wrong       Switch back to some of these:           As time allows:                Blog post for conjure: https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/conju...               - review Tor browser Lox integration https://gitlab.torproject.org/tpo/applications/tor-browser/-/merge_requests/...               - add TTL cache to lox MR for duplicate responses: https://gitlab.torproject.org/tpo/anti-censorship/lox/-/merge_requests/305         - Work on outstanding milestone issues:             - key rotation automation         Later:         pending decision on abandoning lox wasm in favour of some kind of FFI? https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/43096):             - add pref to handle timing for pubkey checks in Tor browser             - add trusted invitation logic to tor browser integration: https://gitlab.torproject.org/tpo/applications/tor-browser/-/issues/42974         - improve metrics collection/think about how to show Lox is working/valuable         - sketch out Lox blog post/usage notes for forum     (long term things were discussed at the meeting!):         - brainstorming grouping strategies for Lox buckets (of bridges) and gathering context on how types of bridges are distributed/use in practice             Question: What makes a bridge usable for a given user, and how can we encode that to best ensure we're getting the most appropriate resources to people?                 1. Are there some obvious grouping strategies that we can already consider?                     e.g., by PT, by bandwidth (lower bandwidth bridges sacrificed to open-invitation buckets?), by locale (to be matched with a requesting user's geoip or something?)                 2. Does it make sense to group 3 bridges/bucket, so trusted users have access to 3 bridges (and untrusted users have access to 1)? More? Less? theodorsm: 2025-06-12         Last weeks:             - Applying for funding from NLnet to implement DTLS 1.3 in Pion. Got through the first round.             - Writing paper for FOCI: continuation of master thesis about reducing distinguishability of DTLS in Snowflake by implementing covert-dtls, further analysis of collected browser fingerprint and stability test of covert-dtls in snowflake proxies. Draft: https://theodorsm.net/FOCI25             - Key takeaways:                 * covert-dtls is stable when mimicking DTLS 1.2 handshakes, while the randomization approach— though more resistant to fingerprinting — tends to be less stable.                 * Chrome webextensions are more unstable than standalone proxies                 * covert-dtls should be integrated in Snowflake proxies as they produce the ClientHello messages during the DTLS handshake.                 * Chrome randomizes the order of extension list.                 * Firefox uses DTLS 1.3 by default in WebRTC.                 * A prompt adoption of DTLS 1.3 in both Snowflake and our fingerprint-resistant library is needed to keep up with browsers                 * The evolution of browsers’ fingerprints had no noticeable effect on Snowflake’s number of daily users over the last year.                 * Even with a sharp drop in the amount of proxies, it does not seem to affect the number of Snowflake users.                 * Browser extensions make Snowflake resistant to ClientHello fingerprinting.                 * Standalone proxies can serve more Snowflake clients per volunteer than webextensions.                 * We need metrics on which types of proxies are actually being matched and successfully used by clients.         Next weeks:             - Getting paper camera ready.             - Fix merge conflicts in MR (https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowf...).         Help with:             - Should we do user testing of covert-dtls? Facilitator Queue:     meskio onyinyang shelikhoo 1. First available staff in the Facilitator Queue will be the facilitator for the meeting 2. After facilitating the meeting, the facilitator will be moved to the tail of the queue