websocat
Netcat, curl and socat for WebSockets.
Examples
Connect to public echo server
$ websocat ws://echo.websocket.org
123
123
ABC
ABC
Serve and connect
A$ websocat -s 1234
Listening on ws://127.0.0.1:1234/
ABC
123
B$ websocat ws://127.0.0.1:1234/
ABC
123
Open a tab in Chromium using remote debugging.
$ chromium --remote-debugging-port=9222&
$ curl -sg http://127.0.0.1:9222/json/new | grep webSocketDebuggerUrl | cut -d'"' -f4 | head -1
ws://127.0.0.1:9222/devtools/page/A331E56CCB8615EB4FCB720425A82259
$ printf '{"id":2,"method":"Page.navigate","params":{"url":"%s"}}\n' https://example.com | websocat -n1 --origin http://127.0.0.1:9222 --protocol tcp ws://127.0.0.1:9222/devtools/page/A331E56CCB8615EB4FCB720425A82259
{"id":2,"result":{"frameId":"A331E56CCB8615EB4FCB720425A82259","loaderId":"EF5AAD19F2F8BB27FAF55F94FFB27DF9"}}
Proxy TCP connections to WebSocket connections and back.
$ websocat --oneshot -b ws-l:127.0.0.1:1234 tcp:127.0.0.1:22&
$ websocat --oneshot -b tcp-l:127.0.0.1:1236 ws://127.0.0.1:1234/&
$ nc 127.0.0.1 1236
SSH-2.0-OpenSSH_7.4p1 Debian-10+deb9u3
qwertyu
Protocol mismatch.
Broadcast all messages between connected WebSocket clients
A$ websocat -t ws-l:127.0.0.1:1234 broadcast:mirror:
B$ websocat ws://127.0.0.1:1234
C$ websocat ws://127.0.0.1:1234
Features
- Connecting to and serving WebSockets from command line.
- Executing external program and making it communitate to WebSocket using stdin/stdout.
- Text and binary modes, converting between lines (or null-terminated records) and messages.
- Inetd mode, UNIX sockets (including abstract namesaced on Linux).
- Auto-reconnect and connection-reuse modes.
- Linux, Windows and Mac support, with pre-built executables.
- Low-level WebSocket clients and servers with overridable underlying transport connection.
- Buildable by rust starting from v1.23.0.
Usage
Vitaly "_Vi" Shukela <vi0oss@gmail.com>
Command-line client for web sockets. Like netcat, but for WebSockets. Designed like socat.
USAGE:
websocat ws://URL | wss://URL (simple client)
websocat -s port (simple server)
websocat [FLAGS] [OPTIONS] <addr1> <addr2> (advanced mode)
FLAGS:
(some flags are hidden, see --help=long)
-E, --exit-on-eof Close a data transfer direction if the other one reached EOF
-0, --null-terminated Use \0 instead of \n for linemode
-1, --one-message Send and/or receive only one message. Use with --no-close and/or -u/-U.
--oneshot Serve only once. Not to be confused with -1 (--one-message)
-q Suppress all diagnostic messages, except of startup errors
-s, --server-mode Simple server mode: specify TCP port or addr:port as single argument
-S, --strict strict line/message mode: drop too long messages instead of splitting them, drop
incomplete lines.
-u, --unidirectional Inhibit copying data in one direction
-U, --unidirectional-reverse Inhibit copying data in the other direction (or maybe in both directions if
combined with -u)
-v Increase verbosity level to info or further
-b, --binary Send message to WebSockets as binary messages
-n, --no-close Don't send Close message to websocket on EOF
-t, --text Send message to WebSockets as text messages
OPTIONS:
(some options are hidden, see --help=long)
-B, --buffer-size <buffer_size> Maximum message size, in bytes [default: 65536]
-H, --header <custom_headers>...
Add custom HTTP header to websocket client request. Separate header name and value with a colon and
optionally a single space. Can be used multiple times.
-h, --help <help>
See the help.
--help=short is the list of easy options and address types
--help=long lists all options and types (see [A] markers)
--help=doc also shows longer description and examples.
--origin <origin> Add Origin HTTP header to websocket client request
--protocol <websocket_protocol> Specify Sec-WebSocket-Protocol: header
--websocket-version <websocket_version> Override the Sec-WebSocket-Version value
--ws-c-uri <ws_c_uri> [A] URI to use for ws-c: overlay [default: ws://0.0.0.0/]
ARGS:
<addr1> In simple mode, WebSocket URL to connect. In advanced mode first address (there are many kinds of
addresses) to use. See --help=types for info about address types. If this is an address for
listening, it will try serving multiple connections.
<addr2> In advanced mode, second address to connect. If this is an address for listening, it will accept only
one connection.
Basic examples:
Command-line websocket client:
websocat ws://echo.websocket.org/
WebSocket server
websocat -s 8080
WebSocket-to-TCP proxy:
websocat --binary ws-l:127.0.0.1:8080 tcp:127.0.0.1:5678
Partial list of address types:
ws:// Insecure (ws://) WebSocket client. Argument is host and URL.
wss:// Secure (wss://) WebSocket client. Argument is host and URL.
ws-listen: WebSocket server. Argument is host and port to listen.
stdio: Same as `-`. Read input from console, print to console.
tcp: Connect to specified TCP host and port. Argument is a socket address.
tcp-listen: Listen TCP port on specified address.
sh-c: Start specified command line using `sh -c` or `cmd /C` (depending on platform)
cmd: Start specified command line using `sh -c` (even on Windows)
readfile: Synchronously read a file. Argumen is a file path.
writefile: Synchronously truncate and write a file.
appendfile: Synchronously append a file.
udp: Send and receive packets to specified UDP socket, from random UDP port
udp-listen: Bind an UDP socket to specified host:port, receive packet
mirror: Simply copy output to input. No arguments needed.
literalreply: Reply with a specified string for each input packet.
literal: Output a string, discard input.
Partial list of overlays:
broadcast: Reuse this connection for serving multiple clients, sending replies to all clients.
autoreconnect: Re-establish underlying connection on any error or EOF
Reference
There is a work-in-progress reference document that contains more options and examples.
Technical details
It runs singlethreaded. There is old non-async threaded version in legacy branch of releases prior to 0.5.
IPv6 supported, just use specifiers like ws-l:[::1]:4567
Web socket usage is not obligatory, you can use any specs on both sides.
If you want wss:// server, use socat or nginx in addition to websocat until this function is implemented properly (see nginx.conf sample in the reference document).
Pre-built binaries for Linux (usual and musl), Windows, OS X and Android (ARM) are available on the releases page.
Limitations
- Server for
wss://is not implemented (you can workaround it with Nginx or socat). - Server mode ignores incomding URL and HTTP headers.
Planned features
- Driving SSL server websockets (specifying cert and key)
- Pure Rust version with SSL support?
- SOCK_SEQPACKET mode for
exec:? - SOCK_SEQPACKET SCTP mode?
- Add WebRTC's DataChannel to the mix (separate project)?
There are also checkboxes on issues #1 and #5.
Building from source code
- Install the Rust tool toolchain
cargo build --release.