[tor-project] Anti-censorship meeting notes, 2021 September 2

Cecylia Bocovich cohosh at torproject.org
Thu Sep 2 17:04:59 UTC 2021


Hi everyone!

Here are our meeting logs:

http://meetbot.debian.net/tor-meeting/2021/tor-meeting.2021-09-02-16.00.html

and our meeting pad:

Anti-censorship work meeting pad
--------------------------------

Next meeting: Thursday September 2nd 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 checkin about the status of anti-censorship work at Tor.
Coordinate collaboration between people/teams on anti-censorship at Tor.

== Announcements ==

    Job opening on the anti-censorship team:
https://www.torproject.org/about/jobs/software-developer-anticensorship-2/
\o/


== Discussion ==


- CPU use in proxies and bridge

   -
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40064

   - bridge is sitting at about 200% CPU: about 30% tor, 170%
snowflake-server

   - might be worth doing one round of profiling?

    	- how to profile the bridge? in production or separately?

    	- can use snowbox as a simulation

    - proxies can control CPU use with -capacity option

- Reading group?

   - we'll read "BlindTLS" https://dl.acm.org/doi/10.1145/3473604.3474564

- DocsHackathon:

   - Add a new support item about using Tor in China:
https://gitlab.torproject.org/tpo/web/support/-/issues/210

   - Merging support.torproject.org/gettor into
support.torproject.org/censorship

- TM censorship update

    - do any of our gettor endpoints work in Turkmenistan?

    - archive.org seems to be ok for DNS, HTTP, and HTTPS


== Actions ==

    Update the monthly report for July + August:
https://pad.riseup.net/p/l7d6oBd40EQa3u7cFxIk


== Interesting links ==


https://ntc.party/t/an-open-encyclopedia-of-internet-censorship-persian/1223

    ACM FOCI 2021 papers https://dl.acm.org/doi/proceedings/10.1145/3473604

    "Even Censors Have a Backup: Examining China's Double HTTPS
Censorship Middleboxes" https://dl.acm.org/doi/10.1145/3473604.3474559

    "Measuring QQMail's automated email censorship in China"
https://dl.acm.org/doi/10.1145/3473604.3474560

    "A multi-perspective view of Internet censorship in Myanmar"
https://dl.acm.org/doi/10.1145/3473604.3474562

    "Exploring Simple Detection Techniques for DNS-over-HTTPS Tunnels"
https://dl.acm.org/doi/10.1145/3473604.3474563

    "BlindTLS: Circumventing TLS-based HTTPS censorship"
https://dl.acm.org/doi/10.1145/3473604.3474564

    USENIX Security 2021 papers
https://www.usenix.org/conference/usenixsecurity21/technical-sessions

    "Domain Shadowing: Leveraging Content Delivery Networks for Robust
Blocking-Resistant Communications"
https://www.usenix.org/conference/usenixsecurity21/presentation/wei

    "How Great is the Great Firewall? Measuring China's DNS Censorship"
https://www.usenix.org/conference/usenixsecurity21/presentation/hoang

    "Balboa: Bobbing and Weaving around Network Censorship"
https://www.usenix.org/conference/usenixsecurity21/presentation/rosen

    "Weaponizing Middleboxes for TCP Reflected Amplification"
https://www.usenix.org/conference/usenixsecurity21/presentation/bock

    "Defeating DNN-Based Traffic Analysis Systems in Real-Time With
Blind Adversarial Perturbations"
https://www.usenix.org/conference/usenixsecurity21/presentation/nasr


== Reading group ==

    We will discuss "BlindTLS: Circumventing TLS-based HTTPS censorship"
on 2021-09-23

    https://dl.acm.org/doi/10.1145/3473604.3474564

    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 2021-09-02
Last week:
    - hiring tasks for ac team and network team
    - more s28 scrimmage work
    - got snowflake working in shadow

        - https://github.com/shadow/shadow/pull/1601

    - implemented parsing of networkstatus documents for rdsys (rdsys!14)
    - wrote a draft plug for implementing RTCPeerConnection for v3 manifests
    - reviewed GetTor implementation in rdsys (rdsys!11)
    - reviewed snowflake!52
    - couple other small reviews
This week:
    - snowflake package documentation and API changes (snowflake#40063)
    - more rdsys + BridgeDB deployment work
    - network simulations of Snowflake with shadow
    - censorship measurement tests and tools
    - lots of miscellaneous gitlab TODOs
Needs help with:

    - feedback on v3 plug:
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake-webext/-/issues/29


arlolra: 2021-08-12

    Last week:

    - Migrate to v3 of the webextension manifest

    Next week:

    - Maybe get back to snowflake-webext #10

    - Write up the pitch for our use case for supporting creating
PeerConnections in background service workers
https://github.com/w3c/webrtc-extensions/issues/77

    Help with:

    -


dcf: 2021-09-02

    Last week (since 2021-08-19):

    - helped review snowflake-client SOCKS args
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/merge_requests/53

    - more investigation of blocking in Turkmenistan
https://gitlab.torproject.org/tpo/community/support/-/issues/40030#note_2748011

    - helped analyze go mod issue with goptlib
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40065

    - attended pluggable transports meetup
https://internetfreedomfestival.org/wiki/index.php/September_2_2021_GM

    Next week:

    - fix meek-client test errors
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/meek/-/issues/40002

    - identify cause and fix for the goptlib go.mod issue
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40065

    - reply to Alexander Mages re SCTP pluggable transport
https://lists.torproject.org/pipermail/anti-censorship-team/2021-August/000190.html

    Help with:


agix:2021-07-15

    Last week:

    -Off due to final exams

    Next week:

    -Work on bridgebox for rdsys

    -More research on httpt #4

    Help with:

    -


hanneloresx: 2021-3-4

    Last week:

    - Submitted MR for bridgestrap issue #14

    Next week:

    - Finish bridgestrap #14

    - Find new issue to work on

    Help with:

    -


maxb: 2021-07-15

    Last week:

    - Opened
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/40054
re: utls for broker negotiation

    - Worked on github.com/max-b/nat-testing for
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/issues/25595


    - Added a snowflake-proxy-no-nat and a snowflake-client-no-nat to
help with debugging

    - Successfully making connections from snowflake-client and
snoflake-client-no-nat through the snowflake-proxy-no-nat, but not
having any success with the snowflake-proxy (with nat).

    - Added a local dockerized STUN server

    Next week:

    - Use wireshark to figure out the difference between successful
snowflake-proxy-no-nat and unsuccessful snowflake-proxy-nat

    - Work on implementing different NAT types, particularly in a way
that's conducive to automatic testing

    - Add testing wrapper w/ "pass/fail" conditions


meskio: 2021-09-02

    Last week:

    - work on the moat Censorsip snapshot (bridgedb#40025)

    - merge gettor implemenation (rdsys!11)

    - update snowflake debian package (snowflake#19409)

    - write gettor documentation (rdsys#44)

    - test fixes into snowflake (snowflake!55)

    - run rdsys tests in the CI (rdsys#58)

    - review networkstatus parser (rdsys!14)

    - review rearquitecture to smaller docker image for snowflake-proxy
(docker-snowflake-proxy!1)

    - review and merge gettor updater script (gettor!17)

    - review snowflake Check error for calls to preparePeerConnection
(snowflake!54)

    - review and merge obfs4 docker build for multiple archs
(docker-obfs4-bridge!4)

    Next week:

    - implement censorship snapsot available on moat (bridgedb#40025)

    - add more providers to gettor (rdsys#43)

    - get the snowflake debian package reviewed by a DD (snowflake#19409)

    Help with:

    -


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