Tanzania blocks social media (and Tor?) on election day

WhatsApp blocked in Tanzania on election day

Starting from yesterday (27th October 2020) – on the eve of Tanzania’s 2020 general election – OONI measurements continue to show the ongoing blocking of social media (and of the Tor circumvention tool) in Tanzania.

In this report, we share OONI data collected from Tanzania on these blocks, as well as relevant instructions for further OONI Probe testing.


OONI Probe is free and open source software designed to measure various forms of network interference based on openly specified methodologies. The OONI Probe app, available for both mobile and desktop platforms, includes a variety of tests designed to measure the blocking of websites, instant messaging apps, and circumvention tools (it also includes several network performance related tests). By default, as soon as you run OONI Probe tests, your test results are automatically sent to OONI servers, processed, and openly published in near real-time.

Since 2016, OONI Probe users in Tanzania have contributed more than 80,000 measurements from 30 local networks. On an ongoing basis, OONI Probe users in Tanzania continue to run tests and contribute relevant measurements.

Once we were notified yesterday by community members in Tanzania that they couldn’t access certain social media platforms without the use of a VPN, we immediately looked at (openly available) OONI measurements pertaining to the recent testing of social media websites and apps in Tanzania.

More specifically, we looked at the following OONI measurements:

Since we heard of increased VPN use in Tanzania (following reported difficulties in accessing social media platforms), we also looked at relevant OONI measurements to check whether access to circumvention tools was blocked as well.

OONI Probe, however, currently only includes tests for the following 2 circumvention tools: Tor and Psiphon. We therefore looked at the measurements collected from these 2 tests in Tanzania, as well as at relevant Web Connectivity measurements that pertain to the testing of circumvention tool websites.

The findings shared below are based on these openly available measurements.

Blocking of social media

Today, on election day, access to WhatsApp, Facebook Messenger, and Telegram appears to be blocked in Tanzania.


Starting from yesterday (27th October 2020), we observe the blocking of WhatsApp on multiple networks in Tanzania.

In many cases, we see that attempts to connect to WhatsApp Web (web.whatsapp.com) and to WhatsApp’s registration service fail, resulting in generic timeout errors. Yet, TCP connections to the tested endpoints of WhatsApp’s mobile app are often successful. Nonetheless, the failed attempts to WhatsApp Web and to WhatsApp’s registration service suggest that access to both WhatsApp Web and to WhatsApp’s mobile app was most likely blocked in Tanzania.

This is further suggested by the following (main) factors:

It therefore seems highly probable that access to WhatsApp was in fact blocked (on multiple networks) in Tanzania amid their 2020 general election. Recent measurements collected at around 5PM UTC on 28th October 2020 from Tanzania suggest that access to WhatsApp remains blocked.

The blocking of WhatsApp in Tanzania is further suggested by OONI Probe Web Connectivity measurements (though they are few), which show that the testing of www.whatsapp.com presented anomalies on 3 different networks during the same time frame.

Facebook Messenger

Facebook Messenger appears to be blocked on multiple networks in Tanzania on election day as well (starting from 27th October 2020).

We observe that access to Facebook Messenger is blocked in different ways on different networks. For example, some measurements (collected today) from MIC Tanzania (AS37035) show that TCP connections to Facebook’s endpoints were successful, but DNS lookups did not resolve to Facebook IP addresses. On Airtel (AS37133), we see that DNS lookups resolved to Facebook IP addresses, but a few TCP connections to Facebook endpoints failed. Similarly, on Viettel (AS327885) we see that a few TCP connections to Facebook endpoints failed (but the DNS lookups were successful).

Similarly to the testing of WhatsApp, we observe a consistent pattern where the testing of Facebook Messenger consistently presented anomalies on multiple networks in Tanzania from 27th October 2020 onwards, while previous measurements (collected over the last months) show that the app used to be reachable. This (along with the fact that many locals in Tanzania reported difficulties using Facebook over the past day) therefore provides a strong signal that access to Facebook Messenger was interfered with amid Tanzania’s 2020 general election.


Along with WhatsApp and Facebook Messenger, access to Telegram appears to have been blocked on multiple networks in Tanzania as well.

Measurements collected today from Tanzania show that HTTP(S) GET requests to web.telegram.org did not return a consistent response (suggesting blocking of Telegram Web), while many attempted connections to Telegram endpoints failed (suggesting potential blocking of Telegram’s mobile app as well). This, for example, is evident on Airtel (AS37133) and on Tanzania Telecommunications (AS33765). In other cases – such as on Zanzibar Telecom (AS36930) – we see that Telegram Web appears blocked, but connections to the tested Telegram endpoints were successful. This suggests that while web.telegram.org may have been blocked, the Telegram mobile app may have worked on this network (unless they blocked access to different Telegram endpoints that weren’t tested as part of the OONI Probe Telegram test).

Similarly to WhatsApp and Facebook Messenger, we observe the same pattern where the testing of Telegram consistently presents anomalies on multiple networks in Tanzania (from 27th October 2020 onwards), while previous measurements collected over the last months show that Telegram used to be reachable. Along with the fact that many locals in Tanzania reported experiencing difficulties using Telegram (without a VPN) during this period, it seems likely the case that access to Telegram was blocked amid Tanzania’s 2020 general election.

Social media websites

In addition to social media apps, Internet Service Providers (ISPs) in Tanzania appear to have likely blocked access to several social media websites as well.

Almost all OONI measurements collected from the testing of twitter.com in Tanzania since yesterday, 27th October 2020, consistently suggest that access to the site was blocked on multiple networks. Across several different networks, we see that the HTTP experiment failed, resulting in generic timeout errors.

We observe the same type of failures in the testing of www.instagram.com in Tanzania on 27th October 2020 on Viettel (AS327885) and Vodacom (AS36908), but the limited volume of relevant measurements limits our ability to confirm this with confidence.

Among other social media sites that presented signs of potential blocking (such as www.tiktok.com), we see www.youtube.com. Every time the site was tested over the last day (6 times in total on 2 networks), we consistently see that the HTTP experiment always failed, resulting in generic timeout errors (similarly to the testing of twitter.com and www.instagram.com). While the relatively limited testing coverage of social media sites limits our confidence in confirming their blocking, it’s worth noting nonetheless that they present the same types of failures (signaling that they might have in fact been blocked).

Blocking of Tor?

Circumventing these censorship events may have been a bit challenging in Tanzania, given the fact that we observe what seems to be the blocking of Tor, which can be used for circumventing internet censorship (in addition to its online privacy and anonymity properties).

As of 27th October 2020 (on the eve of Tanzania’s 2020 general election), we observe that the testing of Tor resulted in many timeout failures, suggesting that access to Tor might have been blocked. To check whether Tor works (in a tested network), the OONI Probe Tor test measures the reachability of Tor directory authorities (used by Tor relays), OR port (used by Tor bridges), OR port of directory authorities (used by Tor clients), and obfs4 (Tor bridge that speaks the OBFS4 protocol).

As part of Tor testing in Tanzania, in many cases (between 27th to 28th October 2020), we see that most attempted connections to OR ports and obfs4 addresses failed (resulting in generic timeout errors). This is evident on several local networks, such as MIC Tanzania (AS37035), Vodacom (AS36908), and Viettel (AS327885). Given that previous Tor measurements (collected over the last months, before 26th October 2020) showed that Tor worked in Tanzania (most Tor Browser bridges were reachable and almost all connections to Tor directory authorities were successful), the sudden failure of Tor testing (as seen on several networks in multiple measurements), along with the parallel blocking of social media platforms, suggest that access to Tor may have been interfered with in Tanzania amid its 2020 general election. It is also possible, however, that these timeouts may be the result of network congestion (rather than intentional blocking).

That said, it may still be possible to connect to Tor from Tanzania through the use of private Tor bridges. It’s also worth highlighting that the number of timeouts varied across tests, and that a few connections to default Tor bridges and Tor directory authorities were successful. Regardless of potential interference, the Tor network saw a spike in both directly connecting Tor users and Tor bridge users in Tanzania.

The following chart, taken from Tor Metrics, shows that the number of directly connecting Tor users in Tanzania has been increasing over the last days.

Tor Metrics: Directly connecting users from Tanzania

Going forward, we aim to improve upon the OONI Probe Tor experiment to bootstrap tor from desktop probes, which could help with ruling out false positives and better evaluating whether Tor works in a tested network.

On a few occasions (on 27th and 28th October 2020), the testing of the Psiphon VPN in Tanzania presented some anomalies on a few networks. While the OONI Probe Psiphon test was able to bootstrap Psiphon, it was unable to fetch a webpage from the internet. However, most Psiphon measurements (collected from several networks in Tanzania over the last day) show that it was possible to successfully bootstrap Psiphon and use it to fetch web pages, suggesting that Psiphon currently works in Tanzania.

Further testing

In general, the more measurements we have available, the greater confidence we may have in confirming censorship events. Longitudinal measurements also enable us to examine whether and how censorship events change over time.

If you are in Tanzania and interested in contributing (more) OONI measurements, you can do so through the following steps:

  1. Install the OONI Probe mobile app

  2. Tap Run (to run all tests)

For more targeted testing, we also recommend the following:

  1. Open the Social media button in this page (when accessed from a mobile browser)

  2. Open that button with your OONI Probe mobile app (instead of a browser)

  3. Tap Run (to test 39 internationally relevant social media websites)


  1. Open the VPNs button in this page (when accessed from a mobile browser)

  2. Open that button with your OONI Probe mobile app (instead of a browser)

  3. Tap Run (to test 21 circumvention tool websites)

In all cases, please have your VPN turned off when running OONI Probe tests (to help ensure more accurate test results).

Once you have run OONI Probe tests, you will find your measurements in the Test Results section of your OONI Probe app. By default (unless you have opted out), all of your test results are automatically openly published in near real-time. By contributing measurements, you are not only increasing transparency of internet censorship in Tanzania, but you are also enabling researchers and advocates to monitor censorship events as they emerge.

Warm thanks to all OONI Probe users in Tanzania for making this study possible.