Psiphon

About Psiphon

Psiphon is a free and open source tool that utilizes VPN, SSH, and HTTP proxy technology for censorship circumvention. The Psiphon VPN essentially serves as a tunnel that enables you to circumvent censorship because you access resources on the internet through the non-censored tunnel that Psiphon provides.

In an attempt to limit censorship circumvention, some governments have blocked access to Psiphon. OONI has therefore developed an OONI Probe test that anyone can run to measure the reachability of the Psiphon app.

Psiphon test

The OONI Probe Psiphon test provides an automated way of examining whether the Psiphon app works in a tested network.

This test starts off by using Psiphon code to bootstrap a Psiphon tunnel. Once the test has bootstrapped and created the Psiphon tunnel, it then checks whether it actually works. To determine this, the test attempts to fetch a webpage to see if it’s possible to use Psiphon in order to connect to websites on the internet.

As part of this process, there are 3 possible outcomes:

1. Psiphon bootstraps and it’s able to fetch a webpage from the internet. Psiphon works in the tested network and can be used to circumvent internet censorship.

2. Psiphon bootstraps, but it’s unable to fetch a webpage from the internet. The Psiphon tunnel has been created, but it can’t be used for accessing resources on the internet. Therefore, Psiphon does not work on this network, and access to the app may be blocked.

3. Psiphon does not bootstrap. It is not even possible to create the Psiphon tunnel to get started. Therefore, Psiphon does not work on this network, and access to the app may be blocked.

Read the Psiphon test specification.