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# webcat - netcat for websockets
Connect to a websocket server:
webcat ws://example.com:3000/
Start a websocket server listening on port 3000:
webcat -l 3000
The server only accepts one client at a time. The client auto-reconnects.
## Setting up a MITM debugging proxy
To debug stateful protocols on top of websockets, it is helpful to be able to
inject messages to the server or the client in a real session, acting as a
man-in-the-middle (MITM). On Linux you can achieve this using `webcat` and
FIFOs as follows:
mkfifo client-in server-in
webcat ws://example.com:3000/ < client-in > server-in
webcat -l 4000 < server-in > client-in
echo > server-in # unblock the FIFO deadlock
You can now connect your client to ws://localhost:4000/.
And inject messages by writing to the named pipes:
echo "Hello from webcat" > client-in
Note that when redirecting stdout the messages are automatically printed to
stderr, so you can still observe what's happening.
## Limitations
* no support for messages containing newlines
(cannot send them, cannot distinguish them from separate messages)
* no support for WebSocket Secure (`wss://`)
(webcat is meant for local testing & debugging, wss is out of scope)
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