User:Weinshel/Internet censorship circumvention/

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Link to original article: Internet censorship circumvention

Informal notes: User:Weinshel/Notes_on_censorship_circumvention

Ed. note: my changes in this article so far have been restructuring and reworking the Methods section, and adding a new section with examples of adoption of tools. I also plan on slightly revising the lead section and the "Circumvention, anonymity, risks, and trust" section.

Methods (replace existing section)[edit]

Ed. note: I restructured this section in the existing article, and also reworded portions and added some citations.

There are many methods available that may allow the circumvention of Internet filtering, which can widely vary in terms of implementation difficulty, effectiveness, and resistance to detection.

Alternate names & addresses[edit]

Filters may block specific domain names, either using DNS hijacking or URL filtering. Sites are sometimes accessible through alternate names and addresses that may not be blocked.[1]

Some websites may offer the same content at multiple pages or domain names.[2] For example, the English Wikipedia is available at https://en.wikipedia.org/, and there is also a mobile-formatted version at https://en.m.wikipedia.org/.

If DNS resolution is disrupted but the site is not blocked in other ways, it may be possible to access a site directly through its IP address. Using DNS servers other than those supplied by default by an ISP may bypass DNS-based blocking.[1] OpenDNS and Google offer DNS services or see List of Publicly Available and Completely Free DNS Servers.

Censors may block specific IP addresses. Depending on how the filtering is implemented, it may be possible to use different forms of the IP address (specifing the address in a different base).[3] For example, the following URLs all access the same site, although not all browsers will recognize all forms: http://208.80.152.2 (dotted decimal), http://3494942722 (decimal), http://0320.0120.0230.02 (dotted octal), http://0xd0509802 (hexadecimal), and http://0xd0.0x50.0x98.0x2 (dotted hexadecimal).

Mirrors, caches, and copies[edit]

When a specific site is blocked, there may be other copies of the site available…

Cached pages: Some search engines keep copies of previously indexed webpages, or cached pages, which are often hosted by the search engine and may not be blocked. Cached pages may be identified with a small link labeled "cached" in a list of search results. Google allows the retrieval of cached pages by entering "cache:some-blocked-url" as a search request.[4]

Mirror and archive sites: Copies of web sites or pages may be available at mirror or archive sites such as the Internet Archive's Wayback Machine.


RSS aggregators: RSS aggregators such as Google Reader and Bloglines may be able to receive and pass on RSS feeds that are blocked when accessed directly.[5]

Proxying[edit]

Web proxies are websites that are configured to allow users to load external web pages through the proxy server, permitting the user to load the page as if it is coming from the proxy server and not the (blocked) source.[5] However, depending on how the proxy is configured, a censor may be able to determine the pages loaded and/or determine that the user is using a proxy server.[2]

For example, the mobile Opera Mini browser uses a proxy-based approach employing encryption and compression in order to speed up downloads. This has the side effect of allowing it to circumvent several approaches to Internet censorship. In 2009 this led the government of China to ban all but a special Chinese versions of the browser.[6]

Domain fronting: Circumvention software can implement a technique called domain fronting, where the destination of a connection is hidden by passing the initial requests through a content delivery network or other popular site.[7] This technique was used by messaging applications including Signal and Telegram, but has since been blocked by high-profile cloud service providers.[8]

SSH tunneling: By establishing an SSH tunnel, a user can forward all their traffic over an encrypted channel, so both outgoing requests for blocked sites and the response from those sites are hidden from the censors, for whom it appears as unreadable SSH traffic.[9]

Virtual private network (VPN): Using a VPN, A user who experiences internet censorship can create a secure connection to a more permissive country, and browse the internet as if they were situated in that country.[citation needed] Some services are offered for a monthly fee; others are ad-supported.

Tor: More advanced tools such as Tor route encrypted traffic through multiple servers to make the source and destination of traffic less traceable. It can in some cases be used to avoid censorship, especially when configured to use traffic obfuscation techniques.[10]

Directions for Tor Pluggable Transports, which use traffic obfuscation techniques to increase censorship resistance.

Traffic obfuscation[edit]

A censor may be able to detect and block use of circumvention tools. There are efforts to make circumvention tools less detectable by randomizing the traffic, attempting to mimic a non-blocked protocol, or tunneling traffic through a whitelisted service by using techniques including domain fronting.[10] Tor and other circumvention tools have adopted multiple obfuscation techniques that users can use depending on the nature of their connection, which are sometimes called "Pluggable Transports."[11]


Adoption of circumvention tools (new section)[edit]

Circumvention tools have seen spikes in adoption in response to high-profile blocking attempts,[12][13] however, studies measuring adoption of circumvention tools in countries with persistent and widespread censorship report mixed results.[14]

In response to persistent censorship[edit]

Measures of circumvention tool adoption have reported divergent results. A 2010 study by Harvard University researchers estimated that very few users use censorship circumvention tools—likely less than 3% of users even in countries that consistently implement widespread censorship.[14]

In China, adoption of circumvention tools is particularly high in certain communities, such as universities,[15][16] and a survey by Freedom House found that users generally did not find circumvention tools to be difficult to use.[1] Estimates of the use of Twitter, a blocked social media service, have ranged from 10 million (1.5% of the internet-using population),[17] to 35 million[18] (disputed[19]). Yet efforts to block circumvention tools have reduced adoption of those tools; the Tor network previously had over 30,000 users connecting from China but as of 2014 had only approximately 3,000 Chinese users.[20]

On the other hand, in a 2017 study of internet users from Thailand, a research group at the University of Washington found that 63% of surveyed users attempted to use circumvention tools, and 90% were successful in using those tools. Users often made on-the-spot decisions on tools to use based of limited or unreliable information, and had a variety of perceived threats, some more abstract and others more concrete based on personal experiences.[21]

In response to blocking events[edit]

In response to the 2014 blocking of Twitter in Turkey, information about alternate DNS servers was widely shared, as using another DNS server such as Google Public DNS allowed users to access Twitter.[22] The day after the block, the total number of posts made in Turkey was up 138%, according to Brandwatch, an internet measurement firm.[12]

After a April 2018 ban on the Telegram messaging app in Iran, web searches for VPN and other circumvention software increased as much as 48x for some terms, but there was evidence that users were downloading unsafe software. As many as a third of Iranian internet users used the Psiphon tool in the days immediately following the block, and in June 2018 as many as 3.5 million Iranian users continued to use the tool.[13]

Software (existing section)[edit]

Otherwise leave this section mostly as is (it isn't great but the focus of my edits is more on other sections)

References[edit]

Potential additional sources[edit]

Some China sources[23][24][25]

https://cyber.harvard.edu/pubrelease/internet-control/

https://cyber.harvard.edu/publications/2017/06/GlobalInternetCensorship

https://cyber.harvard.edu/publication/2018/censorship-and-collateral-damage

https://www.bloomberg.com/quicktake/great-firewall-of-china

https://www.usenix.org/conference/usenixsecurity18/presentation/vandersloot

Open access links[edit]

TODO: figure out how to add these to the normal citations

https://homes.cs.washington.edu/~yoshi/papers/GebhartEtAl-IEEEEuroSP.pdf

https://arxiv.org/abs/1605.04044v2

  1. ^ a b c Callanan, Cormac; Dries-Ziekenheiner, Hein; Escudero-Pascual, Alberto; Guerra, Robert (2011-04-11). "Leaping Over the Firewall: A Review of Censorship Circumvention Tools" (PDF). freedomhouse.org. Retrieved 2018-12-11.
  2. ^ a b "How to: Circumvent Online Censorship". Surveillance Self-Defense. 2014-08-05. Retrieved 2018-11-01.
  3. ^ "Circumventing Network Filters Or Internet Censorship Using Simple Methods, VPNs, And Proxies" Archived 14 November 2011 at the Wayback Machine, Not As Cool As It Seems, 16 December 2009, accessed 16 September 2011
  4. ^ "View web pages cached in Google Search Results - Google Search Help". support.google.com. Retrieved 2018-12-11.
  5. ^ a b Everyone's Guide to By-passing Internet Censorship, The Citizen Lab, University of Toronto, September 2007
  6. ^ Steven Millward (22 November 2009). "Opera accused of censorship, betrayal by Chinese users". CNet Asia. Archived from the original on 3 November 2013.
  7. ^ Fifield, David; Lan, Chang; Hynes, Rod; Wegmann, Percy; Paxson, Vern (2015-06-01). "Blocking-resistant communication through domain fronting". Proceedings on Privacy Enhancing Technologies. 2015 (2): 46–64. doi:10.1515/popets-2015-0009. ISSN 2299-0984. S2CID 5626265.
  8. ^ Bershidsky, Leonid (3 May 2018). "Russian Censor Gets Help From Amazon and Google". Bloomberg. Retrieved 9 November 2018.
  9. ^ Hoffman, Chris. "How to Use SSH Tunneling to Access Restricted Servers and Browse Securely". How-To Geek. Retrieved 2018-12-11.
  10. ^ a b Dixon, Lucas; Ristenpart, Thomas; Shrimpton, Thomas (14 December 2016). "Network Traffic Obfuscation and Automated Internet Censorship". IEEE Security & Privacy. 14 (6): 43–53. arXiv:1605.04044. doi:10.1109/msp.2016.121. ISSN 1540-7993. S2CID 1338390.
  11. ^ Shahbar, K.; Zincir-Heywood, A. N. (2015-11-09). "Traffic flow analysis of tor pluggable transports". 2015 11th International Conference on Network and Service Management (CNSM): 178–181. doi:10.1109/CNSM.2015.7367356. ISBN 978-3-9018-8277-7. S2CID 1199826.
  12. ^ a b Edwards, John (2014-03-21). "From Pac-Man to Bird Droppings, Turkey Protests Twitter Ban". WSJ. Retrieved 2018-11-15.
  13. ^ a b Kargar, Simin; McManamen, Keith (2018). "Censorship and Collateral Damage: Analyzing the Telegram Ban in Iran". SSRN Electronic Journal. doi:10.2139/ssrn.3244046. ISSN 1556-5068. S2CID 159020053. SSRN 3244046.
  14. ^ a b "2010 Circumvention Tool Usage Report". Berkman Klein Center. Retrieved 2018-11-15.
  15. ^ "VPN crackdown a trial by firewall for China's research world". South China Morning Post. Retrieved 2018-11-15.
  16. ^ Branigan, Tania (2011-02-18). "China's Great Firewall not secure enough, says creator". The Guardian. ISSN 0261-3077. Retrieved 2018-12-11.
  17. ^ "Twitter estimates that it has 10 million users in China". TechCrunch. Retrieved 2018-12-11.
  18. ^ "Twitter Grows Stronger in Mexico - eMarketer". www.emarketer.com. Retrieved 2018-12-11.
  19. ^ Ong, Josh (2012-09-26). "Report: Twitter's Most Active Country Is China (Where It Is Blocked)". The Next Web. Retrieved 2018-12-11.
  20. ^ Crandall, Jedidiah R.; Mueen, Abdullah; Winter, Philipp; Ensafi, Roya (2015-04-01). "Analyzing the Great Firewall of China Over Space and Time". Proceedings on Privacy Enhancing Technologies. 2015 (1): 61–76. doi:10.1515/popets-2015-0005. S2CID 14705481.
  21. ^ Gebhart, Genevieve; Kohno, Tadayoshi (26 April 2017). "Internet Censorship in Thailand: User Practices and Potential Threats". 2017 IEEE European Symposium on Security and Privacy (EuroS&P). IEEE: 417–432. doi:10.1109/eurosp.2017.50. ISBN 9781509057627. S2CID 11637736.
  22. ^ "Turkish citizens use Google to fight Twitter ban". The Verge. Retrieved 2018-11-15.
  23. ^ Zittrain, Jonathan; Edelman, Benjamin G. (2003). "Internet Filtering in China". SSRN Electronic Journal. doi:10.2139/ssrn.399920. ISSN 1556-5068. S2CID 219723432.
  24. ^ MacKinnon, Rebecca (2007-08-09). "Flatter world and thicker walls? Blogs, censorship and civic discourse in China". Public Choice. 134 (1–2): 31–46. doi:10.1007/s11127-007-9199-0. ISSN 0048-5829. S2CID 154501423.
  25. ^ Hassid, Jonathan (2012-02-28). "Safety Valve or Pressure Cooker? Blogs in Chinese Political Life". Journal of Communication. 62 (2): 212–230. doi:10.1111/j.1460-2466.2012.01634.x. ISSN 0021-9916.
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