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Through a Router Darkly - Remote Investigation of Internet Censorship
- 1. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Through a Router Darkly – Remote Investigation of Internet Censorship Joss Wright joss.wright@oii.ox.ac.uk @JossWright Oxford Internet Institute University of Oxford Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 1/47
- 2. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Censorship Almost every country engages in some form of Internet filtering. China’s “Golden Shield” is the classic example. Saudi Arabia presents perhaps the most extreme filtering regime. (OpenNet Initiative) Many different technologies; many different filtering targets; many different rationales and justifications. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 2/47
- 3. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Censorship Technologies DNS Poisoning IP Header Filtering Address or protocol. IP Content Filtering Keyword or protocol. DPI Hybrid or Proxy Filtering We can consider takedown, social pressure, legislation as filtering, but will focus on technology. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 3/47
- 4. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions DNS Lookup User Home Router ISP's DNS Server ISP Router User ISP's Network Network A Network B Target Network Q: target.com? A: 82.68.72.161 target.com? target.com? 82.68.72.161 82.68.7.161 target.com → 82.68.72.161 Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 4/47
- 5. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions DNS Hierarchy target.com? target.com? target.com? target.com? `Authoritative' Domain Name Server for target.com `Root' Domain Name Server User's Domain Name Server (usually ISP-operated). Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 5/47
- 6. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Web Request ... target.com 82.68.72.161 User Home Router ISP's DNS Server ISP Router User ISP's Network Network A Network B Target Network http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 6/47
- 7. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions DNS Poisoning User Home Router ISP's DNS Server ISP Router User ISP's Network Network A Network B Target Network Q: target.com? A: 95.45.23.122 target.com? target.com? 95.45.23.122 95.45.23.122 target.com → 95.45.23.122 Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 7/47
- 8. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions IP Header Filtering ... target.com 82.68.72.161 User Home Router ISP's DNS Server ISP Router User ISP's Network Network A Network B Target Network http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 8/47
- 9. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions IP Header Filtering ... target.com 192.168.1.25 User Home Router ISP's DNS Server ISP Router User ISP's Network Network A Network B Target Network http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 9/47
- 10. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions IP Content Filtering (DPI) ... target.com 192.168.1.25 User Home Router ISP's DNS Server ISP Router User ISP's Network Network A Network B Target Network http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 10/47
- 11. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Proxy Filtering ... target.com 82.68.72.161 User Home Router ISP's DNS Server ISP Router User ISP's Network Network A Network B Target Network http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment Censorship Authority Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 11/47
- 12. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Proxy Filtering ... target.com 82.68.72.161 User Home Router ISP's DNS Server ISP Router User ISP's Network Network A Network B Target Network http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment http://82.68.72.161:80/ blog.html?q=enlightenment Censorship Authority Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 12/47
- 13. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Limitations A tradeoff between subtlety and computational requirements. Sophisticated methods require greater computational resources. At national scale, these can be severe. Centralization can cause problems, as seen with CleanFeed. Central management also raises administrative and organizational burdens. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 13/47
- 14. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Localized Filtering We can observe localized filtering in response to local events. We therefore see filtering differ across a state, rather than homogeneity. We also expect filtering to vary over time. We may expect organizations to have one filtering regime, even across a state. This can reveal filtering tactics, methods, reasoning, limitations. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 14/47
- 15. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Existing Work HERDICT: crowdsources filtering information from volunteer web users. OpenNet Initiative: use volunteers and direct means to examine filtering around the world. Both consider national-level filtering as homogeneous. Both also make judgements as to the nature of filtering. Political, religious, social Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 15/47
- 16. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Existing Approaches HERDICT relies on users for information. Visitors to the website report sites that appear blocked. The website actively presents potentially blocked content, allowing users to verify if it is blocked. OpenNet Initiative’s methods vary, but include direct investigation and liason with volunteers in blocked regions. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 16/47
- 17. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Fine-Grained Sources For fine-grained mapping we wish to combine data gathered at various locations with GeoIP data at the city level. GeoIP databases are increasingly cheap and accurate. The problem is to get readings from a wide geographical distribution. Ideally, not just blocking status but type of blocking. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 17/47
- 18. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Limitations Crowdsourcing or using volunteers can be effective if the tool is sufficiently usable, but is limited: Undirected, inconsistent coverage. Direct investigation is expensive. Ideally we desire direct access to filtered internet connections. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 18/47
- 19. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Direct Action Direct access to other connections is possible in some limited cases. Tor exit nodes, and similar services such as psiphon. VPN services or remote shells. Creatively-used public services – webservers, IRC, bittorrent... Access to DNS is very simple, and directly addresses one major type of filtering. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 19/47
- 20. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Direct Action Problems Direct services are rare, especially in countries with interesting filtering. No-one wants to run Tor-like services in filtered areas! VPN services are also rare. Remote shells are even more so. These services are typically offered to get past filtering, not get in. Creative misuse of open services seems the most fruitful option. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 20/47
- 21. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Direct Action Mechanisms DNS is simple and effective for detecting DNS filtering, but is not very useful beyond that. Tor and Tor-like services are rare, but wonderful. Botnets. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 21/47
- 22. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Legality and Ethics Is it legal to access blocked websites? Is it ethical to ask someone else to access blocked websites? Consent for automated tools. Is it legal to creatively abuse a service, with or without malicious intent? Is it ethical to open a service operator to repercussions based around such misuse? Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 22/47
- 23. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Legal Concerns HERDICT Legal FAQ: ”Rules vary by country, but we know of no nation where it is illegal for you to report information about sites you cannot access.” Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 23/47
- 24. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Legal Concerns Sites are sometimes blocked for serious legal or societal reasons: Pornography, homosexuality, lèse majesté, insult to religion Reporting sites as blocked may well be legal, but detection attempts may cause legal or social consequences. When is the risk too small, and how can we judge this against arbitrary cultural contexts? Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 24/47
- 25. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Experiments in China Internet population around 513 million as of December 2011. Geographic, cultural and ethnic diversity. Extremely well-known and active internet censorship regime. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 25/47
- 26. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions China DNS Scanning 278 DNS servers across China from the APNIC WHOIS database. Top 80 reported blocked websites according to HERDICT. DNS query for each site to each server. It would be possible to scan China for additional DNS servers, but this seems unnecessary. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 26/47
- 27. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions DNS Response Types Invalid Server Timeout Unknown Domain Misdirection Genuine Results Redirect Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 27/47
- 28. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Misdirection Domain No Domain No Answer No Nameserver Timeout True IP False IP backchina.com 0 0 13 7 5 162 ntdtv.com 0 0 23 7 0 157 open.com.hk 0 1 20 7 3 156 torproject.org 0 2 24 7 1 153 tibet.net 0 2 22 7 3 153 peacehall.com 0 1 20 7 6 153 6park.com 0 0 26 7 2 152 hotspotshield.com 0 1 29 7 2 148 boxun.com 0 1 29 7 2 148 wezhiyong.org 0 1 33 7 2 144 Ten most misdirected domains from experiments, showing DNS error result counts for each domain. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 28/47
- 29. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions No Such Domain Domain No Domain No Answer No Nameserver Timeout True IP False IP ahrchk.net 4 17 64 40 60 2 killerjo.net 4 17 65 37 62 2 x365x.com 3 17 65 41 59 2 websitepulse.com 3 18 65 36 63 2 voanews.com 3 17 64 38 63 2 tumblr.com 3 17 64 38 37 28 steves-digicams.com 3 17 65 36 64 2 scribd.com 3 17 65 36 38 28 pinyinannotator.com 3 18 67 36 61 2 newgrounds.com 3 16 64 36 66 2 Ten domains most often claimed non-existent. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 29/47
- 31. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Next slide: Locations in China for which we have results. Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 31/47
- 33. oiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioiioxford internet ins�tute university of oxfordoiioiioiioiioiioiio Introduction Information Sources Legality and Ethics Experiments Questions Next slide: Distribution of all cities across China, justifying location of our results. (Note higher density in the East.) Joss Wright Through a Router Darkly – Remote Investigation of Internet Censorship: 33/47