9/24/21, 8:39 PM The State of Internet Censorship in Myanmar | OONI WhatsApp Facebook Messenger The Web Connectivity test was run with the aim of examining whether a set of URLs (included in both the “global test list” and the recently updated “Myanmar test list”) were blocked during the testing period and if so, how. The Vanilla Tor test was run to examine the reachability of the Tor network, while the WhatsApp and Facebook Messenger tests were run to examine whether these instant messaging apps were blocked in Myanmar during the testing period. The HTTP invalid request line and HTTP header field manipulation tests were run with the aim of examining whether “middle boxes” (systems placed in the network between the user and a control server) that could potentially be responsible for censorship and/or surveillance were present in the tested network. The sections below document how each of these tests are designed for the purpose of detecting cases of internet censorship and traffic manipulation. Web Connectivity test This test examines whether websites are reachable and if they are not, it attempts to determine whether access to them is blocked through DNS tampering, TCP/IP blocking or by a transparent HTTP proxy. Specifically, this test is designed to perform the following: Resolver identification DNS lookup TCP connect HTTP GET request By default, this test performs the above (excluding the first step, which is performed only over the network of the user) both over a control server and over the network of the user. If the results from both networks match, then there is no clear sign of network interference; but if the results are different, the websites that the user is testing are likely censored. Further information is provided below, explaining how each step performed under the web connectivity test works. 1. Resolver identification The domain name system (DNS) is what is responsible for transforming a host name (e.g. torproject.org) into an IP address (e.g. 38.229.72.16). Internet Service Providers (ISPs), amongst others, run DNS resolvers which map IP addresses to hostnames. In some circumstances though, ISPs map the requested host names to the wrong IP addresses, which is a form of tampering. As a first step, the web connectivity test attempts to identify which DNS resolver is being used by the user. It does so by performing a DNS query to special domains (such as whoami.akamai.com) which will disclose the IP address of the resolver. 2. DNS lookup https://ooni.org/post/myanmar-report/ 11/19