netcat

Broadcast Netcat to WebSocket Clients

This tutorial describes how to broadcast TCP data to WebSocket clients. Netcat is used as a TCP backend server.

Getting Started

To run this example, you must have Docker installed and have added a host file entry for kaazing.example.com, as described here.

The docker-compose.yml describes the two containers it will run: the Gateway and Netcat. These containers will be launched in the following configuration:

The Gateway container will run a broadcast service that allows WebSocket clients to connect on the front-end. When a TCP message is sent from Netcat, the Gateway will forward that message to all other connected clients. The Gateway config file is configured as follows:

  <service>
    <name>Netcat Broadcast</name>
    <description>
        A service that broadcast from TCP to WebSocket by
        connecting to a TCP Backend listening on tcp://netcat:1000
        and accepting WebSocket connections on ws://kaazing.example.com:8000/
    </description>
    <accept>ws://kaazing.example.com:8000/</accept>
    <connect>tcp://netcat:1000</connect>

    <type>broadcast</type>

    <!-- Restrict cross site constraints before running in production -->
    <cross-site-constraint>
      <!--
        * is not secure for production javascript applications and allows
        access from all origins. See https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS
      -->
      <allow-origin>*</allow-origin>
    </cross-site-constraint>
  </service>

Run

1. Start the containers

docker-compose up -d

2. Connect to the Gateway in a Web browser via http://websocket.org/echo.html?location=ws://kaazing.example.com:8000/

3. To push data through Netcat run :

docker-compose exec netcat nc -l 1000

and then type any message you want to send

This works only for Linux because docker-compose exec command on Windows currently only supports detached mode (-d) -> here

Next Steps

• Learn how to configure the Gateway to encrypt traffic with WebSocket over TLS: WSS