meek is a blocking-resistant pluggable transport for Tor. It encodes a
data stream as a sequence of HTTPS requests and responses. Requests are
reflected through a hard-to-block third-party web server in order to
avoid talking directly to a Tor bridge. HTTPS encryption hides
fingerprintable byte patterns in Tor traffic.
The key trick that makes the system work is "domain fronting":
communicating with a forbidden domain in a way that makes it look like
you are communicating with an allowed domain. It works by putting the
allowed domain on the "outside" of a request: in the DNS query and the
SNI TLS extension; and the forbidden domain on the "inside": in the Host
header of the HTTP request. The trick works with web services that
ignore the SNI and handle requests based on the Host header. Google,
with its App Engine infrastructure at appspot.com, is one of these
services. A client wanting to communicate with a forbidden subdomain of
appspot.com while appearing to communicate with www.google.com can run
the client plugin program like this:
meek-client --url=https://meek-reflect.appspot.com/ --front=www.google.com
meek can use a number of web services as a transport backend. Some of
these, like CDNs, are very easy to set up for domain fronting: you just
point the CDN at an instance of meek-server. Others, like App Engine,
require you to run a small "reflector" app on the service that forwards
requests to meek-server. A description of how to set up various services
is at https://trac.torproject.org/projects/tor/wiki/doc/meek#Webservices.
Reflector apps are found in the appengine, nginx, php, and wsgi
The meek-client program by itself has a fingerprintable TLS handshake.
To disguise the TLS part of HTTPS connections, meek-client should be run
with the --helper option pointing at a browser extension that has been
set up separately. How it works is meek-client tells the browser what
URL to request, the browser requests it and returns the payload to
meek-client. The TLS implementation is that of the browser, so it better
blends in with allowed traffic. A browser extensions for Firefox is in
the firefox directory.
Here is a summary of the programs that appear in subdirectories.
Reflector web app that runs on Google App Engine. The reflector simply
copies requests and responses to an instance of meek-server somewhere. A
public instance of the App Engine web app is at
Browser extension for TLS camouflage.
The client transport plugin, run by a censored client.
An auxiliary program for within Tor Browser that runs a second copy of
Firefox with the browser extension and then configures meek-client to
use it as a helper.
The server transport plugin, run on a Tor relay.
A reflector configuration for Nginx.
A PHP reflector. It can be run on any platform that supports PHP with
the cURL library. A public instance is at
An auxiliary program used on Windows to assist with cleanup of
A WSGI Python reflector.
To the extent possible under law, the authors have dedicated all
copyright and related and neighboring rights to this software to the
public domain worldwide. This software is distributed without any
warranty. See COPYING.