What is Substratum?
Substratum is a cryptocurrency project that aims to build a decentralized web resistant to censorship. Users earn a cryptocurrency token, SUB (based on Ethereum), by running Substratum software on their computers and acting as server nodes (almost like TOR nodes).
This decentralized internet traffic routing would be very useful for people living in China where most major foreign websites and apps are blocked.
But does Substratum work in China? Can you used it to unblock Google and Facebook?
Installing and running Substratum
You can download and install the Substratum Beta from their website. The instructions are pretty straightforward.
- Download and install the Substratum software (Windows, linux macOS)
- Change your DNS to 127.0.0.1
- Run the software in “consuming” mode.
I tried installing Substratum on two Windows machine here in China. It failed on the first one due to an error related to the number of network. I tried disabling the network interfaces but still got the same error when ever I switched to a consuming mode.
Error after switching to consumer mode
I was able to complete the setup on a second Windows computer without having the network interface error. (On the second computer I also had multiple network interfaces already setup but didn’t get the error message for some reason.)
After installing Substratum, I was able to switch to both consuming and serving mode without any error. The DNS was also automatically switched to 127.0.0.1 when using the consuming mode but I had to manually restore the DNS settings after using the application to get back the internet connection.
While testing in consuming mode which I assume reroutes my traffic to a local (substratum managed) DNS, I was able to access sites available in China but unable to access sites blocked by the GFW.
Also, some normally unblocked websites remained unreachable until after I had access them without using Substratum. When I reconnected to Substratum I was able to reach these sites. I will assume these sites were not in the local DNS record the first time I tried to access them and after accessing them without substratum the local DNS record got updated.
There are some few other notes to take into account when running Substratum.
- Your IP address isn’t changed / masked like it would be when using a VPN.
- Unable to run a speed test when using any major speed test website I could find. Those site where unreachable when I was connected to Substratum.
Testing Substratum on Linux (Ubuntu)
- I also ran Substratum on my Ubuntu 16.04 installation. I met a known issues which I found too complicated to try to solve so I abandon. This issue is documented here.
Substratum cannot be used to bypass internet censorship in China at this time.
Since Substratum is still in beta we can expect it to have a lot of issues and complex setup. But one of my concern is that it appears to only act as a DNS proxy (surrogate DNS) which are not viable solution against the GFW since most DNS proxy are easily poisoned by the GFW DNS cache. I think this is the reason why it doesn’t work for other site which are already blocked in China.
We will keep our eye out on Substratum in the future. Hopefully it can be used as a tool to bypass internet censorship in China.