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noVNC is a VNC client implemented using HTML5 technologies,
specifically Canvas and WebSockets (supports 'wss://' encryption).
For browsers that do not have builtin WebSockets support, the project
includes [web-socket-js](http://github.com/gimite/web-socket-js),
a WebSockets emulator using Adobe Flash .
In addition, [as3crypto](http://github.com/lyokato/as3crypto_patched)
has been added to web-socket-js to implement WebSockets SSL/TLS
Special thanks to [Sentry Data Systems](http://www.sentryds.com) for
sponsoring ongoing development of this project (and for employing me).
Running in Chrome before and after connecting:
<img src="http://kanaka.github.com/noVNC/img/noVNC-1.jpg" width=400> <img src="http://kanaka.github.com/noVNC/img/noVNC-2.jpg" width=400>
See more screenshots <a href="http://kanaka.github.com/noVNC/screenshots.html">here</a>.
Unless you are using a VNC server with support for WebSockets
connections (only my [fork of libvncserver](http://github.com/kanaka/libvncserver)
currently), you need to use a WebSockets to TCP socket proxy. There is
a python proxy included ('wsproxy'). One advantage of using the proxy
is that it has builtin support for SSL/TLS encryption (i.e. "wss://").
1. WebSockets is not a pure socket protocol. There is an initial HTTP
like handshake to allow easy hand-off by web servers and allow
some origin policy exchange. Also, each WebSockets frame begins
2. Javascript itself does not have the ability to handle pure byte
arrays. The python proxy encodes the data as base64 so that the
Javascript client can decode the data as an integer array.
* Use the launch script to start a mini-webserver and the WebSockets
proxy. The `--vnc` option is used to specify the location of
a running VNC server:
`./utils/launch.sh --vnc localhost:5901`
* Point your browser to the cut-and-paste URL that is output by the
launch script. Enter a password if the VNC server has one
configured. Hit the Connect button and enjoy!
### Advanced usage
* To encrypt the traffic using the WebSocket 'wss://' URI scheme you
need to generate a certificate for the proxy to load. By default the
proxy loads a certificate file name `self.pem` but the `--cert=CERT`
option 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`
* `tightvnc` provide a nice startup script that can be used to run
a separate X desktop that is served by VNC. To install and run the
server under Ubuntu you would do something like this:
`sudo apt-get install tightvncserver`
The VNC server will run in the background. The port that it runs
on is the display number + 5900 (i.e. 5901 in the case above).
* `x11vnc` can be used to share your current X desktop. Note that if
you run noVNC on the X desktop you are connecting to via VNC you
will get a neat hall of mirrors effect, but the the client and
server will fight over the mouse.
`sudo apt-get install x11vnc`
`x11vnc -forever -display :0`
Without the `-forever` option, x11vnc will exit after the first
disconnect. The `-display` option indicates the exiting X display to
share. The port that it runs on is the display number + 5900 (i.e.
5900 in the case above).
* To run the python proxy directly without using launch script (to
pass additional options for example):
`./utils/wsproxy.py -f source_port target_addr:target_port`
* To run the mini python web server without the launch script:
* Point your web browser at http://localhost:8080/vnc.html
(or whatever port you used above to run the web server). Specify the
host and port where the proxy is running and the password that the
vnc server is using (if any). Hit the Connect button.
In the following table Jaunty is Ubuntu 9.04 and WinXP is Windows XP.
<th>OS</th> <th>Browser</th>
<th>Status</th>
<th>Notes</th>
<td>Jaunty</td> <td>Chrome 5.0.375.29</td>
<td>Excellent</td>
<td>Very fast. Native WebSockets.</td>
<td>Jaunty</td> <td>Firefox 3.5</td>
<td>Large full-color images are somewhat slow from web-socket-js overhead.</td>
</tr> <tr>
<td>Jaunty</td> <td>Firefox 3.0.17</td>
<td>Fair</td>
<td>Works fine but is slow.</td>
<td>Jaunty</td> <td>Opera 10.60</td>
<td>Poor</td>
<td>web-socket-js problems, mouse/keyboard issues. See note 1</td>
<td>Jaunty</td> <td>Arora 0.5</td>
<td>Good</td>
<td>Broken putImageData so large full-color images
are slow. Uses web-socket-js.</td>
<td>Jaunty</td> <td>Konqueror 4.2.2</td>
<td><strong>Broken</strong></td>
<td>web-socket-js never loads</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>WinXP</td> <td>Chrome 5.0.375.99</td>
<td>Excellent</td>
<td>Very fast. Native WebSockets.</td>
<td>WinXP</td> <td>Firefox 3.0.19</td>
<td>Good</td>
<td>Some overhead from web-socket-js.</td>
<td>WinXP</td> <td>Safari 5.0</td>
<td>Fast. Native WebSockets. Broken 'wss://' (SSL) - weird client header</td>
<td>WinXP</td> <td>IE 6, 7, 8</td>
<td><strong>Non-starter</strong></td>
<td>No basic Canvas support. Javascript painfully slow.</td>
* Note 1: Opera interacts poorly with web-socket-js. After two
disconnects the browser tab or Flash often hang. Although Javascript
is faster than Firefox 3.5, the high variability of web-socket-js
performance results in overall performance being lower. Middle mouse
clicks and keyboard events need some work to work properly under
Opera. Also, Opera does not have support for setting the cursor
style url to a data URI scheme, so cursor pseudo-encoding is
disabled.
The client is designed to be easily integrated with existing web
structure and style.
At a minimum you must include the `vnc.js` and `default_controls.js`
scripts and call their load() functions. For example:
<head>
<script src='include/vnc.js'></script>
<script src="include/default_controls.js"></script>
</head>
<body>
<div id='vnc'>Loading</div>
</body>
<script>
window.onload = function () {
DefaultControls.load('vnc');
RFB.load(); };
</script>
See `vnc.html` and `vnc_auto.html` for examples. The file
`include/plain.css` has a list of stylable elements.
The `vnc.js` also includes other scripts within the `include`
sub-directory. The `VNC_uri_prefix` variable can be use override the
URL path to the directory that contains the `include` sub-directory.
### Troubleshooting
You will need console logging support in the browser. Recent Chrome
and Opera versions have built in support. Firefox has a nice extension
called "firebug" that gives console logging support.
First, load the noVNC page with `logging=debug` added to the query string.
For example `vnc.html?logging=debug`.
Then, activate the console logger in your browser. With Chrome it can
be activate using Ctrl+Shift+J and then switching to the "Console"
tab. With firefox+firebug, it can be activated using Ctrl+F12.
Now reproduce the problem. The console log output will give more
information about what is going wrong and where in the code the
problem is located.
If you file a issue/bug, it is very helpful for me to have the last
page of console output leading up the problem in the issue report.
Other helpful issue/bug information: browser version, OS version,
noVNC git version, and VNC server name/version.