Evade Internet censorship with Psiphon

Psiphon is a powerful free tool which is designed to evade internet censorship. Developed and maintained by Psiphon Inc. (although originally written by researchers at Citizen lab on behalf of the OpenNet Initiative(ONI), it uses a combination of VPN, SSH and HTTP Proxy secure communication and obfuscation technologies to bypass the kinds of internet filtering (i.e. censorship) systems commonly used governments.

The beauty of the Psiphon system lies in the fact that it utilizes multiple transport systems, so that if one protocol is blocked by a censor, it will automatically switch to an alternative mechanism. China for example, has been trying to block OpenVPN connections over the last year in a crack-down on VPN use. If Psiphon encounters such a block, it will automatically detect it, and attempt to use a SOCKS Proxy over an SSH tunnel, an SSL proxy, or an HTTP Proxy.

The system works by the Android or Windows client connecting to servers run by Psiphon Inc. Each client has a list of these servers, which are added to over time so that as older servers become blocked there is a backup list of new servers to connect to. System integrity is maintained through each client being digitally signed to certify its authenticity, and each server having embedded certificates to ensure it is the authentic server for that client.

It should be noted that although Psiphon is does not store usage data in a way that allows individual user’s IP addresses to be associated with any individual website visited, Psiphon is intended primarily as a censorship evasion tool, rather than one that guarantees anonymity (for which a regular VPN service or Tor are probably better).

Psiphon is only currently available for Windows and Android, and can be downloaded from here.

Speedtest.net results

We decided to put Psiphon’s various transport protocols to the Speedtest, and got these results on our 20 Mb/s UK connection:

Just our straight internet connection

With Psiphon SSH+

With Psiphon VPN

With Psiphon SSH

Note that for some reason we are not too clear about, Psiphon’s SSH+ and SSH results were faster than without any such connection (especially the upload speeds!). Connection through VPN was painfully slow however.

Update: A spokesperson from Psiphon contacted us to explain that SSH is fast because Psiphon compresses data in this mode. The VPN mode has its bandwidth deliberately restricted, as Psiphon is keen to be all about censorship evasion , and not about downloading movies.

The spokesman also wanted to clarify a slight technical misunderstanding of ours – Psiphon no longer switches automatically between protocols, and if OpenVPN is blocked then users should manually switch to obfuscated SSH or L2TP.