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websockify: WebSockets support for any application/server

websockify was formerly named wsproxy and was part of the noVNC project.

At the most basic level, websockify just translates WebSockets traffic to normal socket traffic. Websockify accepts the WebSockets handshake, parses it, and then begins forwarding traffic between the client and the target in both directions.

News/help/contact

Notable commits, announcements and news are posted to @noVNC

If you are a websockify developer/integrator/user (or want to be) please join the noVNC/websockify discussion group

Bugs and feature requests can be submitted via github issues.

If you want to show appreciation for websockify you could donate to a great non-profits such as: Compassion International, SIL, Habitat for Humanity, Electronic Frontier Foundation, Against Malaria Foundation, Nothing But Nets, etc. Please tweet @noVNC if you do.

WebSockets binary data

Starting with websockify 0.5.0, only the HyBi / IETF 6455 WebSocket protocol is supported. There is no support for the older Base64 encoded data format.

Encrypted WebSocket connections (wss://)

To encrypt the traffic using the WebSocket 'wss://' URI scheme you need to generate a certificate and key for Websockify to load. By default, Websockify loads a certificate file name self.pem but the --cert=CERT and --key=KEY options can override the file name. You can generate a self-signed certificate using openssl. When asked for the common name, use the hostname of the server where the proxy will be running:

openssl req -new -x509 -days 365 -nodes -out self.pem -keyout self.pem

For a self-signed certificate to work, you need to make your client/browser understand it. You can do this by installing it as accepted certificate, or by using that same certificate for a HTTPS connection to which you navigate first and approve. Browsers generally don't give you the "trust certificate?" prompt by opening a WSS socket with invalid certificate, hence you need to have it accept it by either of those two methods.

If you have a commercial/valid SSL certificate with one or more intermediate certificates, concat them into one file, server certificate first, then the intermediate(s) from the CA, etc. Point to this file with the --cert option and then also to the key with --key. Finally, use --ssl-only as needed.

Additional websockify features

These are not necessary for the basic operation.

  • Daemonizing: When the -D option is specified, websockify runs in the background as a daemon process.

  • SSL (the wss:// WebSockets URI): This is detected automatically by websockify by sniffing the first byte sent from the client and then wrapping the socket if the data starts with '\x16' or '\x80' (indicating SSL).

  • Session recording: This feature that allows recording of the traffic sent and received from the client to a file using the --record option.

  • Mini-webserver: websockify can detect and respond to normal web requests on the same port as the WebSockets proxy. This functionality is activated with the --web DIR option where DIR is the root of the web directory to serve.

  • Wrap a program: see the "Wrap a Program" section below.

  • Log files: websockify can save all logging information in a file. This functionality is activated with the --log-file FILE option where FILE is the file where the logs should be saved.

  • Authentication plugins: websockify can demand authentication for websocket connections and, if you use --web-auth, also for normal web requests. This functionality is activated with the --auth-plugin CLASS and --auth-source ARG options, where CLASS is usually one from auth_plugins.py and ARG is the plugin's configuration.

  • Token plugins: a single instance of websockify can connect clients to multiple different pre-configured targets, depending on the token sent by the client using the token URL parameter, or the hostname used to reach websockify, if you use --host-token. This functionality is activated with the --token-plugin CLASS and --token-source ARG options, where CLASS is usually one from token_plugins.py and ARG is the plugin's configuration.

Other implementations of websockify

The primary implementation of websockify is in python. There are several alternate implementations in other languages available in our sister repositories websockify-js (JavaScript/Node.js) and websockify-other (C, Clojure, Ruby).

In addition there are several other external projects that implement the websockify "protocol". See the alternate implementation Feature Matrix for more information.

Wrap a Program

In addition to proxying from a source address to a target address (which may be on a different system), websockify has the ability to launch a program on the local system and proxy WebSockets traffic to a normal TCP port owned/bound by the program.

This is accomplished by the LD_PRELOAD library (rebind.so) which intercepts bind() system calls by the program. The specified port is moved to a new localhost/loopback free high port. websockify then proxies WebSockets traffic directed to the original port to the new (moved) port of the program.

The program wrap mode is invoked by replacing the target with -- followed by the program command line to wrap.

`./run 2023 -- PROGRAM ARGS`

The --wrap-mode option can be used to indicate what action to take when the wrapped program exits or daemonizes.

Here is an example of using websockify to wrap the vncserver command (which backgrounds itself) for use with noVNC:

`./run 5901 --wrap-mode=ignore -- vncserver -geometry 1024x768 :1`

Here is an example of wrapping telnetd (from krb5-telnetd). telnetd exits after the connection closes so the wrap mode is set to respawn the command:

`sudo ./run 2023 --wrap-mode=respawn -- telnetd -debug 2023`

The wstelnet.html page in the websockify-js project demonstrates a simple WebSockets based telnet client (use 'localhost' and '2023' for the host and port respectively).

Installing websockify

Download one of the releases or the latest development version, extract it and run python3 setup.py install as root in the directory where you extracted the files. Normally, this will also install numpy for better performance, if you don't have it installed already. However, numpy is optional. If you don't want to install numpy or if you can't compile it, you can edit setup.py and remove the install_requires=['numpy'], line before running python3 setup.py install.

Afterwards, websockify should be available in your path. Run websockify --help to confirm it's installed correctly.

Running with Docker/Podman

You can also run websockify using Docker, Podman, Singularity, udocker or your favourite container runtime that support OCI container images.

The entrypoint of the image is the run command.

To build the image:

cd docker
docker build -t novnc/websockify .

Once built you can just launch it with the same arguments you would give to the run command and taking care of assigning the port mappings:

docker run -it --rm -p <port>:<container_port> novnc/websockify <container_port> <run_arguments>

For example to forward traffic from local port 7000 to 10.1.1.1:5902 you can use:

docker run -it --rm -p 7000:80 novnc/websockify 80 10.1.1.1:5902

If you need to include files, like for example for the --web or --cert options you can just mount the required files in the /data volume and then you can reference them in the usual way:

docker run -it --rm -p 443:443 -v websockify-data:/data novnc/websockify --cert /data/self.pem --web /data/noVNC :443 --token-plugin TokenRedis --token-source myredis.local:6379 --ssl-only --ssl-version tlsv1_2
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