[tor-project] Anti-censorship team meeting notes, 2023-05-18

Hey everyone!

Here are our meeting logs:

And our meeting pad:

Anti-censorship work meeting pad




Next meeting: Thursday, May 25 16:00 UTC

Weekly meetings, every Thursday at 16:00 UTC, in #tor-meeting at OFTC
(channel is logged while meetings are in progress)

== 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 sponsors, we are working on:
     \* All needs review tickets:
         \* https://gitlab.torproject.org/groups/tpo/anti-censorship/-/merge_requests?scope=all&utf8=%E2%9C%93&state=opened&assignee_id=None
     \* Sponsor 96 <\-\- meskio, shell, onyinyang, cohosh
         \* https://gitlab.torproject.org/groups/tpo/-/milestones/24
     \* Sponsor 139 <\-\- hackerncoder, irl, joydeep, meskio, emmapeel working on it
         \* https://pad.riseup.net/p/sponsor139-meeting-pad

== Announcements ==

== Discussion ==

 \* Reported blocking of Snowflake in China since 2023\-05\-12
     \* https://gitlab.torproject.org/tpo/anti-censorship/censorship-analysis/-/issues/40038
     \* https://github.com/net4people/bbs/issues/249
     \* https://forum.torproject.org/t/snowflake-bridge-does-not-work-in-china-since-days-ago/7635
     \* May have something to do with double rendezvous caused by having 2 bridge lines
         \* "two or more TLS connections with the same SNI within a short time to a Fastly IP address"
         \* got similar reports from two users
             \* for one user the blocking threshold was 2 \(https://github.com/net4people/bbs/issues/249#issuecomment-1547034480), for the other the threshold was 3 \(https://gitlab.torproject.org/tpo/anti-censorship/censorship-analysis/-/issues/40038#note_2903068)
     \* Seems to have stopped since 2023\-05\-15
     \* List of mitigations at https://gitlab.torproject.org/tpo/anti-censorship/censorship-analysis/-/issues/40038#note_2902981
         \* first step, if it happens again, is to specify just 1 bridge in Connection Assist for China
             \* use snowflake\-02 as it is currently more lightly loaded
     \* Web browsers also make 2 or more near\-simultaneous connections, maybe they were getting overblocked and that's why it stopped?
         \* https://kb.mozillazine.org/Network.http.max-connections-per-server
     \* Setting MaxConnsPerHost=1 in snowflake\-client still does a double rendezvous, but to 2 \*different\* Fastly IP addresses rather than the some one twice\.
     \* https://gitlab.torproject.org/tpo/core/tor/-/issues/40578 was for two bridges already, so would not directly fix this case
         \* "we could set numentryguards 1 for snowflake users i guess, but i think we want two"
 \* Update on Analysis of speed deficiency of Snowflake in China, 2023 Q1 https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40251#note_2883879
     \* after a lot of research the proposed solution is to enable datagram transport on webrtc to deal with the packet loss situation
     \* that will convert webrtc into an unreliable channel, and snowflake will add reliablity with kcp
     \* \(Proposal under discussion, discuss on irc meeting next week\)
 \* Research about designing an armored bridge line sharing URL format
     \* https://gitlab.torproject.org/tpo/anti-censorship/team/-/issues/126
 \* Regarding bridge churn for Lox \(https://gitlab.torproject.org/tpo/anti-censorship/lox/lox-overview/-/wikis/Lox-Roadmap?version_id=fbc9ee4f76b1d3cba83a79b4ea1d776c16e0b941#metrics-1)
     \* past research and source code on relay \(not bridge\) churn:
     \* https://metrics.torproject.org/networkchurn.html
     \* https://nymity.ch/sybilhunting/churn-values/
     \* https://www.cs.kau.se/philwint/spoiled_onions/
     \* https://nymity.ch/papers/pdf/winter2014a.pdf#page=22

== Actions ==

== Interesting links ==

 \* Unofficial\(?\) Snowflake extension for Safari in Apple App Store?
     \* https://apps.apple.com/us/app/torproject-snowflake/id1597501940
     \* Previously noted at https://lists.torproject.org/pipermail/anti-censorship-team/2022-February/000222.html

== Reading group ==

 \* We will discuss "Lox: Protecting the Social Graph in Bridge Distribution" on 2023 May 18
     \* https://cypherpunks.ca/~iang/pubs/lox-popets23.pdf
     \* 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 ==

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): last updated 2023-05-18
Last week:
- away
- foci stuff
- reviewed some Lox MRs
- wrote up a Lox roadmap from meeting
- Lox Roadmap · Wiki · The Tor Project / Anti-censorship / Lox / lox-overview · GitLab
This week:
- open issue about archiving snowflake prometheus metrics
- lox-wasm tor browser builds
Needs help with:

dcf: 2023-05-18
Last week:
- did analysis of blocking of the snowflake broker front domain in China Blocking of Snowflake in China, 2023-05-12 (#40038) · Issues · The Tor Project / Anti-censorship / censorship-analysis · GitLab
- commented on shelikhoo's proposal for a new snowflake client–proxy protocol based on unreliable data channels Analysis of speed deficiency of Snowflake in China, 2023 Q1 (#40251) · Issues · The Tor Project / Anti-censorship / Pluggable Transports / Snowflake · GitLab
Next week:
- upgrade tor on snowflake-01 Upgrade tor on snowflake-01 to 0.4.7 (#40270) · Issues · The Tor Project / Anti-censorship / Pluggable Transports / Snowflake · GitLab
- open issue to have snowflake-client log whenever KCPInErrors is nonzero Deploy snowflake-server for QueuePacketConn buffer reuse fix (#40260) (#40262) · Issues · The Tor Project / Anti-censorship / Pluggable Transports / Snowflake · GitLab
- parent: Improve bug discovery process (#40267) · Issues · The Tor Project / Anti-censorship / Pluggable Transports / Snowflake · GitLab
- open issue to disable /debug endpoint on snowflake broker
Help with:

meskio: 2023-05-18
Last week:
- catching up after vacation
- review rdsys metrics for flickering bridges (rdsys!122)
Next week:
- finish webtunnel rdsys support

Shelikhoo: 2023-05-18
Last Week:
- [Merge Request Awaiting] Add SOCKS5 forward proxy support to snowflake (snowflake!64)
- [Research] HTTPT Planning Add HTTPT as a pluggable transport to Tor Browser (#1) · Issues · The Tor Project / Anti-censorship / Pluggable Transports / HTTPT · GitLab
- Research about designing an armored bridge line sharing URL format (Research about designing an armored bridge line sharing URL format (#126) · Issues · The Tor Project / Anti-censorship / Team · GitLab)
- Snowflake Performance Analysis (Ongoing, Analysis of speed deficiency of Snowflake in China, 2023 Q1 (#40251) · Issues · The Tor Project / Anti-censorship / Pluggable Transports / Snowflake · GitLab)
- Trying to fix vantage point(Ongoing)
- logcollector alert system(Implement Alert System for logcollector (#4) · Issues · The Tor Project / Anti-censorship / Connectivity Measurement / logcollector · GitLab)
Next Week/TODO:
- [Research] WebTunnel planning (Continue)
- Try to find a place to host another vantage point
- logcollector alert system
- webtunnel document for proxy operator
- Snowflake Performance Analysis

onyinyang: 2023-05-11
Last week:
- Finished up the Lox library changes to replace gone bridges with new bridges
- Added tests and changes to Lox distributor to support this
- Refactored lox-distributor for readability
This week:
- Adding tests for both Lox library and Lox distributor
- Refactoring rdsys metrics changes to prevent risk of testing in deployment
- Add metrics for flickering bandwidth and ratios seen (!122) · Merge requests · The Tor Project / Anti-censorship / rdsys · GitLab
- Looking into a more reasonable way of storing Lox library data structures:
- Ensure Lox bridge table persists in case of catastrophic failure (#2) · Issues · onyinyang / lox · GitLab
- Make Lox Bridge Table more robust (#3) · Issues · onyinyang / lox · GitLab
(long term things were discussed at the meeting!):
Riseup Pad
- 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 useable 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?
Needs Help with:
- figuring out whether or not the metrics I added to rdsys actually collect what we want them to. I can run prometheus locally, but am unsure how to match this with a realistic onbasca test that can actually show whether the metrics are useful/correct. Is there a known way to do such tests other than deploy and find out? Update: Not yet! but we are going to work on staging for this soon

Itchy Onion: 2023-05-11
Last week:
- Continue investigating offline bridges (team#112)
- Discovered bridgestrap#37 (cache gives wrong status of bridge sometimes)
- Start working on rdsys#56 (persistent storage for certain bridge arributes)
This week:
- Continue working on rdsys#56 (Sign in · GitLab)

hackerncoder: 2023-04-20
last week:
- (py-)ooni-exporter torsf (snowflake)
- (py-)ooni-exporter web_connectivity
Next week:
- work on "bridgetester"?
- how does Iran block bridges?