❄️ Snowflake Generalized

Censorship circumvention software like Snowflake, but faster thanks to not using Tor.

Acts as a TCP or UDP tunnel between the user (client) and the server, much like ssh -L.

This, in turn, allows the client to access any blocked TCP / UDP service, such as a SOCKS proxy or your favorite (but blocked) VPN service provider.

Background knowledge

Snowflake is developed by The Tor Project. As of 2024, it can only be used to access the Tor network.

A Snowflake client is embedded into Tor Browser and Orbot. Orbot provides VPN-like functionality by tunneling traffic through Tor, optionally accessing Tor through bridges, such as Snowflake.

(An altered figure from the Snowflake paper (which you should check out (it's not that hard to read)))

But, as you might imagine, making your traffic bounce off of 1 + 3 relays (extra 1 is a Snowflake proxy) before it reaches the destination could be quite slow.
If you're only looking to browse Instagram or YouTube or whatever else is blocked for you, and you don't care about anonymity that Tor provides, you'd want Snowflake to connect directly (or at least more directly) to where you want to go, and not through a huge chain of relays.

Luckily, as it turns out, Tor is not inherent in Snowflake. And this is where our project comes in!

How it works

Pretty much like Snowflake. In fact you can argue that this project is just Snowflake, but with adjusted arguments.
The source code is mostly boilerplate.

Is it production-ready?

Not yet.

The real power of a Snowflake network comes from the numerosity of its proxies. Ideally we'd want one huge Snowflake network (which the original one from The Tor Project is) where proxies are happy to pass client's traffic wherever the client wishes, without making the proxy operator install an extra browser extension or a Docker container per each server that they want to let clients get unrestricted access to.
But, as was said, by default the proxies can only forward traffic to just a few set-in-stone Tor relays.

In order to change that and let proxies connect to arbitrary addresses, we need to make a lot of hardening changes to the proxy's code such that they cannot be abused, e.g. for DDoS, access to the proxy operator's private network, or distribution of illegal content.
And I am trying to do just that with my recent MRs.

Why did you make the project?

My dream is: Snowflake clients can access any service they want with the help of Snowflake proxies, without having to route the traffic through the (not the fastest) Tor network, and the Snowflake proxies don't have to worry about being abused, and that all VPN providers have a Snowflake server running, ready to accept clients for whom their service is blocked.

Snowflake is a fascinating concept and I think it has a lot of potential.

Usage

Also see <./server/examples>

---

Let's make a setup that will work in the same way as

ssh -L localhost:2080:example.com:80 my-server-1.my-domain.com -N

That is, if you connect with TCP to localhost:2080 on your local machine, the connection will be performed to example.com:80 from my-server-1.my-domain.com.

A Snowflake network consists of components of 4 types. In production, each component usually runs on a different machine, but for testing purposes you can run all of them locally.

Prerequisites

• Install Go.

1. Set up the broker

It is not possible to use the already set up Snowflake broker maintained by The Tor Project because as of 2024 it refuses clients who ask to connect to servers other than the ones maintained by The Tor Project.
This might change in the future. Keep an eye on this issue.

1. Download the original Snowflake code.

   git clone https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake.git

2. _

   cd snowflake/broker

3. Create a list of available Snowflake servers. Replace wss://my-server-1.my-domain.com:7901 with the URL that your Snowflake server (not the broker!) is gonna listen on. We're gonna set up the said server in the next steps.

   echo '{"displayName":"my", "webSocketAddress":"wss://my-server-1.my-domain.com:7901", "fingerprint":"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"}' > bridgeListMy.txt

   This step might become unnecessary after this MR is merged.

4. Run the broker. Follow the original instructions to set up TLS ecnryption.

   Or you can run it ⚠️ without encryption. Again, replace my-server-1.my-domain.com with the hostname of your Snowflake server, and localhost:4444 with the address that you want the broker to listen on.

   go run . \
       -disable-geoip \
       -disable-tls \
       -addr=localhost:4444 \
       -allowed-relay-pattern='^my-server-1.my-domain.com$' \
       -bridge-list-path=bridgeListMy.txt

2. Set up a proxy

1. Download the original Snowflake code.

   git clone https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake.git

2. _

   cd snowflake/proxy

3. Run the proxy.

   Replace http://localhost:4444 with the URL of your broker, and ^my-server-1.my-domain.com$ with the same pattern that you set for the broker (i.e. your server's hostname).
   Omit keep-local-addresses in production.

   go run . \
       -broker='http://localhost:4444' \
       -verbose \
       -allowed-relay-hostname-pattern='^my-server-1.my-domain.com$' \
       -allow-non-tls-relay \
       -keep-local-addresses

3. Set up the server

1. Download this project's code.

   https://github.com/WofWca/snowflake-generalized.git

2. _

   cd snowflake-generalized/server

3. Run the server.

   Replace example.com:80 with the desired destination. In practice you'd want it to be a SOCKS / VPN / Tor server running on the same machine as the server. Also replace localhost:7901 with :7901 if you want the server to be publicly reachable. ⚠️ Remove -disable-tls and add acme-hostnames=... to enable encryption.

   go run . \
       -destination-address='example.com:80' \
       -listen-address='localhost:7901' \
       -disable-tls

4. Run the client

1. Download this project's code.

   https://github.com/WofWca/snowflake-generalized.git

2. _

   cd snowflake-generalized/client

3. Run the client!

   Again, replace broker-url with the URL of the broker from a previous step and (optionally) server-id with the one that you used in bridgeListMy.txt.
   Omit keep-local-addresses in production.

   go run . \
       -listen-address='localhost:2080' \
       -broker-url='http://localhost:4444' \
       -server-id='AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA' \
       -keep-local-addresses

Now open up the browser and go to http://localhost:2080. If you see a dummy 404 page, then it worked!

Now feel free to replace example.com:80 with a real service of your choosing.

Addendum

Thanks to The Tor Project for making the Snowflake library easy to use!