[tor-project] Anti-censorship team meeting notes, 2022-06-16

Shelikhoo shelikhoo at torproject.org
Thu Jun 16 17:17:23 UTC 2022


Hey everyone!

Here are our meeting logs:
http://meetbot.debian.net/tor-meeting/2022/tor-meeting.2022-06-16-15.59.html 
<http://meetbot.debian.net/tor-meeting/2022/tor-meeting.2022-03-31-15.59.html>

And our meeting pad:
Anti-censorship work meeting pad

--------------------------------

Next meeting: Thursday June 23rd 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 Tor.

== 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 28
             * must-do tickets: 
https://gitlab.torproject.org/groups/tpo/-/milestones/10
             * possible tickets: 
https://gitlab.torproject.org/groups/tpo/-/issues?scope=all&utf8=%E2%9C%93&state=opened&label_name%5b%5d=Sponsor%2028&milestone_title=None
         * Sponsor 96
             * https://gitlab.torproject.org/groups/tpo/-/milestones/24

== Announcements ==

     * Distributed Snowflake, IP Change Rate Measurement is ready for 
merge src Shell
         * Shell will handle the merge
         * Will wait for a day when others are online to do the deployment
         * Will deploy both new features at once

== Discussion ==

     * What is the status of adjusting snowflake (pion) DTLS signature 
to avoid blocking in Russia? (Based on offset of supported_groups 
extension.)
         * 
https://gitlab.torproject.org/tpo/anti-censorship/censorship-analysis/-/issues/40030#note_2804998
         * https://github.com/pion/dtls/pull/474
         * https://ntc.party/t/webrtc/2174/21
         * 
https://gitlab.torproject.org/tpo/community/support/-/issues/40050 
(generally)
         * UDP packets matching the pattern 
`^\x16\xfe[\xfd\xff].{X}\x00\x1d\x00\x17\x00\x18` are getting blocked, 
where X is a small number of enumerated byte offsets, and 
\x00\x1d\x00\x17\x00\x18 is the supported_groups extension. One of the 
offsets happens to match where pion/dtls places the extension in its 
Client Hello.
         * Concise description of the current situation: snowflake 
connections are blocked when either peer in the connection is Pion-based 
(e.g. snowflake-client or proxy-go) and takes the role of the DTLS client.
             * Put another way, the connection is ok if: the proxy is a 
browser proxy (not proxy-go) and snowflake-client operates as a DTLS 
server, not client
         * Pull request 474 has the risk of creating a new, even more 
distinctive fingerprint
             * So does altering the offset of supported_groups without 
changing other aspects of the fingerprint
         * One idea is to make a patch or fork of pion/dtls with either 
pull request 474 or some other change that alters the offset, then ask 
people to test it
             * 
https://gitweb.torproject.org/builders/tor-browser-build.git/commit/?id=7ffd69a21b8a408a2be9cfdbe7401e1a7f974310 
is a past temporary fork for a fingerprinting fix
             * 
https://archive.org/details/snowflake-ru_snowflake_fix-20211208-ae7cc478fd34 
is the resulting bundle that we asked people to test
             * Shell will create a ticket for releasing a version of 
Snowflake/TorBrowser with patch applied

== Actions ==


== Interesting links ==


== Reading group ==

     * We will discuss "Even Censors Have a Backup: Examining China's 
Double HTTPS Censorship Middleboxes" on June 23
         * https://dl.acm.org/doi/10.1145/3473604.3474559
         * 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): last updated 2022-06-16 (will miss meeting)
Last week:
     - conjure station-side changes
     - updated conjure test environment using cloud-init vms
This week:
     - continued work on conjure PT
     - continue snowflake maintenance tasks
Needs help with:

dcf: 2022-06-16
     Last week:
         - snowflake CDN bookkeeping 
https://gitlab.torproject.org/tpo/anti-censorship/team/-/wikis/Snowflake-costs
         - commented on dnstt pluggable transport client 
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/trac/-/issues/40001#note_2811603
         - commented on restarts for snowflake probetest 
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40147#note_2812079
     Next week:
         - look at STATUS VERSION proposal 
https://gitlab.torproject.org/tpo/core/torspec/-/merge_requests/63
     Help with:

meskio: 2022-06-02
     Last week:
             - use systemd to run bridgedb (team#72)
             - update debian package for snowflake (snowflake#40143)
             - don't use entropy in snowflake tests (snowflake!96)
             - contact cymru about their builtin bridges, as they have 
an old version of obfs4proxy
     Next week:
             - start working on gettor (rdsys#105)

Shelikhoo: 2022-06-16
    Last Week:
      - [Merge Request] Add Distributed Snowflake Server Support 
(snowflake!87)
      - [Merge Request] Distributed Snowflake Bridges (Javascript ver.) 
(snowflake-webext!29)
      - [Merge Request] Implement metrics to measure snowflake churn 
(https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/34075) 
(snowflake!95)
         - [Merge Request Awaiting] Add SOCKS5 forward proxy support to 
snowflake (snowflake!64)
         - [Discussion & Deployment] Migrating Controlling git repo to 
Tor Gitlab Instance (shelikhoo/LogCollectorAncillary#5) <- awaiting/blocked
         - [Research & Discussion] Discussion about the possibility of 
adding PT support to V2Ray to serve the role of HTTPT 
(https://gitlab.torproject.org/tpo/anti-censorship/team/-/issues/82)
         - [Investigate] China "Anti-Fraud" Webpage Redirection 
Censorship (censorship-analysis#40026): update the research based on 
updated ooni result
    Next Week:
           - [Deployment] Snowflake Broker
           - [Coding & Deployment] Proposal: Centralized Probe Result 
Collector (anti-censorship/team#54)
           - [Research & Coding] WebSocket + CDN Based Probe Control 
Connection Forwarder (shelikhoo/LogCollectorAncillary#3)
           - [Investigate] China "Anti-Fraud" Webpage Redirection 
Censorship (censorship-analysis#40026): update the research based on 
updated ooni result

Itchy Onion: 2022-06-16
     Last week:
         - ongoing debugging s28 issues 81 (snowflake crashes in 
stree-testing)
         - taking over part of testing snowflake
     This week:
         - ongoing debugging s28 issues 81, fixing a leaking file 
descriptor issue
         - taking over part of testing snowflake

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