Main Content

Create Encrypted Connection to Remote Applications and Containers

If you want to create a encrypted connection between your local client machine and an application running on a remote machine, you can use SSH tunneling. Some applications transmit information without adding encryption. To access this type of applications over the internet using encryption, use SSH tunneling, also called SSH port forwarding. Doing so provides an encrypted connection between the local client machine and the remote application such as a container session. If the remote host or the local machine is protected by a firewall, you must use SSH tunnelling.

SSH Tunneling

These instructions show you how to forward a port on the client machine to a port on the remote machine. For example, if you create a port forwarding mechanism between port 5903 on your client machine and port 5902 on the remote machine, all connections to localhost:5903 are automatically forwarded to remotehost:5902, where localhost and remotehost are the names or IP addresses of your local and remote machines, respectively. Therefore, if you set up port 5902 on the remote machine to allow you to access a container session, then you can access the container session directly from localhost:5903. After you set up an SSH tunnel, all communication between the client port and the container session is encrypted.

Using PuTTY on a Windows Client

If you are using PuTTY to connect to your remote machine, add a new forwarded port using the menu option Change Settings, accessible by right clicking the title bar of a PuTTY session. In the PuTTY Configuration dialog box, under Category, choose Connection > SSH > Tunnels.

To connect via VNC, set up a tunnel to the container port 5901 (default VNC port).

  • In the Source port field, enter a free port on the client machine starting at 5900, for example 5903.

  • In the Destination field, enter the relevant host port that you connected to container port 5901 when you executed the docker run command, for example, localhost:5902. Note that you must use localhost and not the name of the host machine. This is because the Destination field interprets localhost as the name of the destination machine.

To connect via a web browser, set up a tunnel to the container port 6080 (default noVNC port).

  • In the Source port field, enter a free port on the client machine, for example 6082.

  • In the Destination field, enter the relevant host port that you connected to container port 6080 when you executed the docker run command, for example, localhost:6081. Note that you must use localhost and not the name of the host instance. This is because the Destination field interprets localhost as the name of the destination machine.

If you are using multiple containers or running a VNC server on the client machine, you must increment the source ports on the client machine until you find a free port, for example, 5905 or 6085.

Using a Command-Line Interface

If you are using a command-line interface to SSH tunnel to a container port, use a command of this form:

ssh -L clientport:hostport ubuntu@MyRemoteMachine

clientport is a free port on the client machine, for example 5903 or 6082. hostport is the host port that you connected to the container port when you executed the docker run command, for examplelocalhost:5902 or localhost:6081. Note that you must use localhost and not the name of the host instance. This is because the hostport argument interprets localhost as the name of the host machine.

For example, use the following command:

ssh -L 5903:localhost:5902 ubuntu@MyCompanyDGX1

If you are running a VNC server on the client machine, you must increment the client ports until you find a free port, for example 5905 or 6085.

Connect to Container Desktop

To connect to the container desktop you must ensure that you started a VNC server and mapped a container port to a port on the remote Docker host when you executed the docker run, for example:

docker run -it --rm -p 5902:5901 -p 6081:6080 --shm-size=512M mathworks/matlab:r2021a -vnc
where the flag -vnc starts the VNC server and the flag -p maps the Docker host ports 5902 and 6081 to the container ports 5901 and 6080, respectively. For more information about running the MATLAB® container and using these flags, see MATLAB Container on Docker Hub.

After you set up SSH tunneling, to connect using a web browser on your local machine, use the URL:

http://localhost:6082

Note that you must use localhost and not the name of the host instance.

If you incremented the client port when making the tunnel, use the appropriate client port number, for example 6085.

After you set up SSH tunneling, to connect with VNC, use your VNC client to connect to the appropriate display port on the client, for example:

localhost:3 

Note that you must use localhost and not the name of the host instance.

If you incremented the client port when making the tunnel, use the appropriate client display port number, for example, 5 for port 5905.

Related Topics