list

List of Pluggable Transports

Table of known PTs, tracking multiple different properties including language, platform support, TCP/UDP support, and other useful metrics: https://docs.google.com/spreadsheets/d/132n5eD52RkRAHFD8y1xvyKACH5iQb933E_c2vmX8UHg/edit?usp=sharing

Currently deployed PTs

These Pluggable Transports are currently deployed in Tor Browser, and you can start using them by downloading and using Tor Browser.

obfs4

• Description: Is a transport with the same features as ScrambleSuit but utilizing Dan Bernstein's elligator2 technique for public key obfuscation, and the tor protocol for one-way authentication. This results in a faster protocol.
• Language: Go
• Maintainer: Yawning Angel
• Evaluation: doc/PluggableTransports/Obfs4Evaluation

doc/meek

• Description: Uses HTTP, relays through a third party, TLS for obfuscation.
• Language: Go.
• Maintainer: David Fifield
• Evaluation: doc/PluggableTransports/MeekEvaluation

Format-Transforming Encryption (FTE)

• Description: Transforms data to arbitrary application-layer traffic.
• Language: Python/C++
• Maintainer: Kevin Dyer
• Evaluation: doc/PluggableTransports/FteEvaluation

ScrambleSuit

• Description: Sophisticated look-like-nothing pluggable transport (in obfsproxy)
• Language: Python
• Maintainer: Philipp Winter
• Evaluation: doc/PluggableTransports/ScrambleSuitEvaluation
• Status: Deployed, but superseded by obfs4 (Tor Browser)

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Deprecated PTs;

These PTs was once part of Tor Browser, but are not used anymore, most of the time because a better version have come out.

Dust

• Description: Look-like-nothing pluggable transport.
• Language: Python
• Notes: Superseded by Dust2
• Maintainer: Brandon Wiley

StegoTorus

• Description: Pluggable transport with modular output formats.
• Language: C++
• Notes: Part of DEFIANCE framework
• Maintainer: vmon (?)

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Undeployed PTs

These Pluggable Transports exist but are not deployed as part of the Tor Browser.

obfs3

• Description: Look-like-nothing pluggable transport (in obfsproxy)
• Language: Python
• Maintainer: asn
• Evaluation: doc/PluggableTransports/Obfs3Evaluation

obfs2

• Description: Look-like-nothing pluggable transport (in obfsproxy)
• Language: Python
• Notes: Superseded by obfs3
• Maintainer: asn
• Evaluation: doc/PluggableTransports/Obfs2Evaluation

Flashproxy

• Description: Zerg-like browser-based proxies XXX
• Language: Python, Go, Javascript
• Maintainer: David Fifield
• Uses websocket-server on the server side, which can also be used with a standalone websocket-client, without going through a flash proxy.
• Evaluation: doc/PluggableTransports/FlashproxyEvaluation

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Other PTs being developed

SnowFlake

• Description: Intends to modernize the flashproxy concept with a more modern NAT traversal algorithm centered around ​WebRTC.
• Language: The implementation is mostly Go, except for the WebRTC implementation, written in C/C++, which is called from the Go application via the cgo FFI interface.
• Maintainer: Serene H.
• Evaluation: doc/PluggableTransports/SnowFlakeEvaluation

basket2

• Description: Modular obfs4 update with fingerprinting resistance, framing, negotiation, PQ
• Language: Go
• Maintainer: Yawning
• Evaluation: doc/PluggableTransports/basket2evaluation

SkypeMorph

• Description: transforms Tor traffic flows so they look like Skype Video - design paper.
• Maintained: Ian Goldberg.

bananaphone

• Description: Markov-chains pluggable transport
• Language: Python
• Maintainer: David Stainton

LODP

• Description: UDP-based pluggable transport.
• Language: C
• Maintainer: Yawning

sshproxy

• Description: SSH-based pluggable transport.
• Language: Python
• Notes: Actually uses the ssh binary
• Maintainer: Yawning

hexchat

• Description: XMPP-based pluggable transport.
• Language: Python (SleekXMPP)
• Notes: Bandwidth issues since most XMPP servers are throttled. Can be solved maybe with multiple hexchat bots.
• Maintainer: Feynmann

Dust2

• Description: Transforms traffic to arbitrary formats based on sample traffic.
• Language: Go / Python
• Evaluation: doc/PluggableTransports/Dust2Evaluation
• Maintainer: Brandon Wiley

Code Talker Tunnel (previously: SkypeMorph)

• Description: Skype-based pluggable transport
• Language: C/C++
• Notes: Actually uses the Skype binary
• Maintainer: Ian Goldberg

git

• Description: Git-based pluggable transport (in obfsproxy)
• Language: Python
• Notes: Git is poll-based. Slow.
• Maintainer: Björgvin Ragnarsson && Pieter Westein

Castle

• Description: Encodes messages as commands in online video games.
• Status: Prototyped.
• Language: C++.

marionette

• Description: An updated FTE proxy.
• Notes: (Presentation). Includes many formats.
• Language: Python

lampshade

• Description: multiplexing. mostly follows obfs4
• Language: go
• Maintainer: oxtoacart

TapDance

• Description: TLS encryption MITM'ed by a participating ISP
• Language: Go (client) / Rust+C (server)
• Notes: Unlike Telex, ISP uses a passive tap. Part of refraction.network
• Maintainer: Sergey

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PT libraries

• pyptlib is a Python library which makes it easier to turn a proxy into a Tor pluggable transport.
• goptlib is a pluggable transports library for golang. Check the example client and example server.
• PLUTO: Pluggable Libraries Using Transport Obfuscation for Android.
• liballium is a C/C++ library for people that absolutely need to use C or C++ for a pluggable transport.