Snowflake

Overview

Snowflake is a pluggable transport that proxies traffic through temporary proxies using WebRTC, a peer-to-peer protocol with built-in NAT punching. It aims to work kind of like flash proxy, but without flash proxy's problems with NAT.

Work in progress.

• [tor-dev] Introducing Snowflake (webrtc pt)
• technical writeup
• thesis chapter

User graph: https://metrics.torproject.org/userstats-bridge-transport.html?transport=snowflake.

Evaluation at PluggableTransports/SnowFlakeEvaluation.

欢迎测试 Tor 浏览器的新网桥 (目前仅支持 Mac OS X 与 Linux) (#22782 (closed) has been fixed, it needs to be retested now)

How to run a Snowflake proxy

Option 1 (addon)

Firstly make sure you have WebRTC enabled. Then you can install this addon for Firefox or this one for Chrome which will let you become a Snowflake proxy. It can also inform you about how many people you have helped in the last 24 hours.

Option 2 (web browser)

In a browser where WebRTC is enabled:

1. Go to https://snowflake.torproject.org/embed and toggle the button to opt in to being a proxy. You shouldn't close that page if you want to remain a snowflake bridge.

Option 3 (standalone)

0. First you will need to install and configure Go to build the standalone proxy-go code. If you are running Ubuntu or Debian, you can install Go by executing apt install golang. Otherwise visit https://golang.org/dl/. Once it is installed, set up your workspace and environment variables (more detailed instructions here: https://golang.org/doc/code.html#Workspaces).

mkdir -p ~/go/src
echo "export GOPATH=$HOME/go" >> ~/.bash_profile
source ~/.bash_profile

1. Clone the source code the src/ directory of your workspace.

cd $GOPATH/src
git clone https://git.torproject.org/pluggable-transports/snowflake.git

2. Get the dependencies and build the source code.

cd snowflake
cd proxy
go get
go build

3. For our fallback proxy-go instances on snowflake-broker, we manage proxy-go instances using runit. However, a simpler nohup command will also allow you to run an instance in the background.

nohup ./proxy &

Source code

https://gitweb.torproject.org/pluggable-transports/snowflake.git

The following should result in a 100% bootstrap over WebRTC:

git clone https://git.torproject.org/pluggable-transports/snowflake.git
cd snowflake/client
go get
go build
tor -f torrc

Integration with Tor Browser

Snowflake is included in alpha releases of Tor Browser.

Integration of Snowflake into stable Tor Browser is being tracked at ticket #19001 (closed).

To build from source code, see doc/TorBrowser/Hacking. In the tor-browser-build directory, make alpha or make testbuild will result in browsers with included Snowflake.

WebRTC fingerprintability

Notes at Snowflake/Fingerprinting.

Reporting bugs

There are two ways to file a bug report:

1. Request an account at the Tor Project GitLab, then open a new issue in the Snowflake project.
2. Edit the public bug-reporting pad of the anti-censorship team.

Please try to be as descriptive as possible with your ticket and if possible include log messages that will help us reproduce the bug.