Shapeshifter Transports is a set of Pluggable Transports implementing the Go API from the Pluggable Transports 2.0 specification

golang, anticensorship, internet-freedom, censorship-circumvention, pluggable-transports
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The Operator Foundation

Operator makes usable tools to help people around the world with censorship, security, and privacy.


The Shapeshifter project provides network protocol shapeshifting technology (also sometimes referred to as obfuscation). The purpose of this technology is to change the characteristics of network traffic so that it is not identified and subsequently blocked by network filtering devices.

There are two components to Shapeshifter: transports and the dispatcher. Each transport provide different approach to shapeshifting. These transports are provided as a Go library which can be integrated directly into applications. The dispatcher is a command line tool which provides a proxy that wraps the transport library. It has several different proxy modes and can proxy both TCP and UDP traffic.

If you are a tool developer working in the Go programming language, then you probably want to use the transports library directly in your application.

If you want a end user that is trying to circumvent filtering on your network or you are a developer that wants to add pluggable transports to an existing tool that is not written in the Go programming language, then you probably want the dispatcher. Please note that familiarity with executing programs on the command line is necessary to use this tool.

If you are looking for a complete, easy-to-use VPN that incorporates shapeshifting technology and has a graphical user interface, consider Moonbounce, an application for macOS which incorporates shapeshifting without the need to write code or use the command line.

Shapeshifter Transports

This is the repository for the shapeshifter transports library for the Go programming language. If you are looking for a tool which you can install and use from the command line, take a look at the dispatcher instead:

The transports implement the Pluggable Transports 2.1 specification available here: Specifically, they implement the Go Transports API v2.1.

The purpose of the transport library is to provide a set of different transports. Each transport implements a different method of shapeshifting network traffic. The goal is for application traffic to be sent over the network in a shapeshifted form that bypasses network filtering, allowing the application to work on networks where it would otherwise be blocked or heavily throttled.

The following transports are currently provided by the library:


Replicant is Operator's flagship transport which can be tuned for each adversary. It is designed to be more effective and efficient that older transports. It can be quickly reconfigured as filtering conditions change by updating just the configuration file.


Optimizer is a pluggable transport that works with your other transports to find the best option. It has multiple configurable strategies to find the optimal choice among the available transports. It can be used for numerous optimization tasks, such as round robin load spreading among multiple transport servers or minimizing latency given multiple transport configurations.

You can find more information on using Optimizer in the ReadMe

shadow (Shadowsocks)

Shadowsocks is a simple, but effective and popular network traffic obfuscation tool that uses basic encryption with a shared password. shadow is a wrapper for Shadowsocks that makes it available as a Pluggable Transport.

More information can be found on the ReadMe


meeklite is a transport which implements Domain Fronting techniques to hide traffic inside of HTTPS requests. In order to use meeklite, you need the meekserver and to set up special hosting through a compatible CDN such as Azure.


obfs4 is a looks-like-nothing obfuscation protocol that incorporates ideas from Philipp Winter's deprecated ScrambleSuit transport.

obfs4 uses the ntor cryptographic handshake protocol with Elligator keys and NaCl encryption.

More information can be found on the Readme


Dust is the original polymorphic protocol shapeshifting transport. It is contemporary with other tunable transports such as ScrambleSuit, FTE, and Marionette. While Dust is highly configurable, it also has high overhead. It is recommended that most users try Replicant first, which incorporates some of the ideas of Dust while being more efficient in terms of the bandwidth used.


obfs2 is an older transport which provides basic encryption. It is not recommended that you use obfs2, however it is included as some users are still using it in areas where it remains effective.


The Shapeshifter transports are written in the Go programming language. To compile it you need to install Go:

If you already have Go installed, make sure it is a compatible version:

go version

The version should be 1.14 or higher.

If you get the error "go: command not found", then trying exiting your terminal and starting a new one.

In order to use a transport in your project, you must have Go modules enabled in your project. How to do this is beyond the scope of this document. You can find more information about Go modules here:

To use in your project, simply import the specific transport that you want to use, for example:

import ""

Your go build tools should automatically add this module to your go.mod and go.sum files. Otherwise, you can add it to the go.mod file directly. See the official Go modules guide for more information on this.

Please note that the import path includes "/v2" to indicate that you want to use the version of the module compatible with the PT v2.0 specification. This is required by the Go modules guide. The modules are actually compatible with the PT2.1 specification, but Go modules only let you specify the major version number, v2.

When you build your project, it should automatically fetch the correct version of the transport module.

Using the Library

The Shapeshifter Transports are just a Go library. In order to use the transports, you will need to integrate them into your application, which is presumably also written in Go. For details on the Go API for Pluggable Transports, refer to the Pluggable Transports 2.0 draft 1 specification.

Frequently Asked Questions

What transport should I use in my application?

Try Replicant, Operator's flagship transport which can be tuned for each adversary. Email for a sample config file for the adversary of interest. shadow is also a good choice as it works on many networks and is easy to configure.

obfs4 is a popular choice, however we receive many comments from users that are frustrated when trying to set up obfs4. Therefore, we recommend that you try Replicant or shadow first and use obfs4 if you need it for your specific network. When trying to install obfs4, please read the shapeshifter-dispatcher documentation examples carefully as most issues we see with setting up obfs4 are the result of not properly following the instructions.

If you are an application developer using Pluggable Transports, feel free to reach out to the Operator Foundation for help in determining which transport might work best for your application. Email

My application is not written in Go. Can I still use the transports?

Yes, the Go API is only one way to integrate transports into your application. There is also an interprocess communication (IPC) protocol that allows you to control a separate process (called the dispatcher) which provides access to the transports through a proxy interface. When using this method, your application can be written in any language. You just need to implement the IPC protocol so that you can communicate with the dispatcher. The IPC protocol is specified in the Pluggable Transports 2.1 specification section 3.3 and an implementation of the dispatcher is available which you can bundle with your application here:


shapeshifter-transports is a collection of different transports written by different authors:

  • Operator Foundation - Replicant, Optimizer, and shadow (wrapper for Shadowsocks)
  • David Fifield - meeklite and meekserver
  • Yawning Angel - obfs4 (design and implementation) and obfs2 (implementation)
  • Dr. Brandon Wiley - Dust