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KasmVNC - Linux Web Remote Desktop

Kasm Technologies developed Kasm Workspaces, the Containerized Streaming Platform. Kasm has open-sourced the Workspace docker images, which include containerized full desktops and apps and base images intended for developers to create custimized streaming containers. These containers can be used standalone or within the Kasm Workspaces Platform which provides a full Enterprise feature set. KasmVNC is used as the streaming tech for our container images, however, you can use KasmVNC for individual servers. While the term VNC is in the name, KasmVNC is not intended to remain compliant with the RFB spec and has different goals than other VNC projects:

  • Web-based - KasmVNC is designed to provide a web accessible remote desktop. It comes with a web server and websocket server built in. There is no need to install other components. Simply run and navigate to your desktop's URL on the port you specify. While you can still tun on the legacy VNC port, it is disabled by default.
  • Security - The RFB specification (VNC) limits the password field to 8 characters, so while the client may take a longer password, only the first 8 characters are sent. KasmVNC defaults to HTTPS with HTTP Basic Auth and disables the legacy VNC authentication method which is not sufficiently secure for internet accessible systems.
  • Simplicity - KasmVNC aims at being simple to deploy and configure.


Since this is a fast evolving project, the documents on the tip of master are chaning rapidly and will not match releases. Be sure to use the README and other documentation from the release branch that matches the version of KasmVNC you are using. Do not use the README from the master branch, unless you are compiling KasmVNC yourself from the tip of master. All releases starting at 0.9.3 have a branch named in the format 'release/0.9.3', for example.

New Features!

  • Webp image compression for better bandwidth usage
  • Automatic mixing of webp and jpeg based on CPU availability on server
  • Multi-threaded image encoding for smoother frame rate for servers with more cores
  • Full screen video detection, goes into configurable video mode for better full screen videoo playback performance.
  • Dynamic jpeg/webp image coompression quality settings based on screen change rates
  • Seemless clipboard support (on Chromium based browsers)
  • Binary clipboard support for text, images, and formatted text (on Chromium based browsers)
  • Allow client to set/change most configuration settings
  • Data Loss Prevention features
    • Key stroke logging
    • Clipboard logging
    • Max clipboard transfer size up and down
    • Min time between clipboard operations required
    • Keyboard input rate limit
    • Screen region selection
  • Deb packages for Debian, Ubuntu, and Kali Linux included in release.
  • RPM packages for CentOS, Oracle, OpenSUSE, Fedora. RPM packages are currently not updatable and not released, though you can build and install them. See build documentation.
  • Web API added for remotely controlling and getting information from KasmVNC
  • Multi-User support with permissions that can be changed via the API
  • Web UI uses a webpack for faster load times.
  • Network and CPU bottleneck statistics
  • Relative cursor support (game pointer mode)
  • Cursor lock
  • IME support for languages with extended characters
  • Better mobile support

Future Goals:

  • UDP transport for faster frame rates
  • H264 encoding



# Please choose the package for your distro here (under Assets):
wget <package_url>

sudo apt-get install ./kasmvncserver_*.deb

# We provide an example script to run KasmVNC at #
# /usr/share/doc/kasmvncserver/examples/kasmvncserver-easy-start. It runs a VNC
# server on display :10 and on interface If you're happy with those
# defaults you can just use it as is:
sudo ln -s /usr/share/doc/kasmvncserver/examples/kasmvncserver-easy-start /usr/bin/

# Add your user to the ssl-cert group
sudo addgroup $USER ssl-cert
# You will need to re-connect in order to pick up the group change

# Create a KasmVNC user able to use keyboard and mouse:
vncpasswd -u $USER -w

# Create ~/.vnc directory and corresponding files.
kasmvncserver-easy-start -d && kasmvncserver-easy-start -kill

# Modify vncstartup to launch your environment of choice, in this example LXDE
# This may be optional depending on your system configuration
echo '/usr/bin/lxsession -s LXDE &' >> ~/.vnc/xstartup

# Start KasmVNC with debug logging:
kasmvncserver-easy-start -d

# Tail the logs
tail -f ~/.vnc/`hostname`:10.log

Now navigate to your system at https://[ip-address]:8443/

To stop a running KasmVNC:

kasmvncserver-easy-start -kill

The options for vncserver:

Argument Description
depth Color depth, for jpeg/webp should be 24bit
geometry Screensize, this will automatically be adjusted when the client connects.
websocketPort The port to use for the web socket. Use a high port to avoid having to run as root.
cert SSL cert to use for HTTPS
sslOnly Disable HTTP
interface Which interface to bind the web server to.


Would you like to contribute to KasmVNC? Please reachout to us at We have investigated or are working on the following, if you have experience in these fields and would like to help please let us know.

Real-time H264 encoding using NVIDIA and Intel encoding technology.

Windows version of KasmVNC. We have been able to get it to compile for Windows and increased the performance, but still not releasable. Experienced Windows developers with a background in cross compiling would help.

ARM version of KasmVNC, we have had requests for this and at one point we did have an ARM build of KasmVNC but it takes dev cycles to mainain and bring it back to life.

Compiling From Source

See the builder/ We containerize our build systems to ensure highly repeatable builds.

License and Acknowledgements