The free product, NoMachine, does not support connections by SSH. SSH is supported in any of the products of the Enterprise Family like Enterprise Desktop, Workstation, Terminal Server and so on. For a comprehensive view of the products in the enterprise range, please check the following sections:

https://www.nomachine.com/enterprise

https://www.nomachine.com/terminal-server

If you try to connect using an SSH connection to a server where the Free Edition is installed, you will get the following message: 

SSH connections are not supported on this server.

To connect to a host where you have installed the free to download NoMachine package, you need to connect via NX protocol. Starting a new connection from the Player > Machines will connect using NX by default.

If you prefer to use SSH, you can tunnel the NX protocol in a SSH connection. Pre-requisite is to have a SSH client on your client machine and a SSH server on your server machine. Follow the instructions below to tunnel via a SSH connection:

Open the tunnel from a console on your NoMachine client host. Let's assume that you want to use port 4003 : 

   $ ssh -L 4003:localhost:4000 username@serverhost

username is a user who can connect to the server by SSH and server host is the IP address or hostname of the machine where NoMachine is installed. 

For example:

$ ssh -L 4003:localhost:4000 john@192.168.1.10

Then start the NoMachine connection.

Related articles:

If you are getting an "Authentication failed" error when connecting by SSH, please consult:
https://www.nomachine.com/AR01L00771

For "The NoMachine service is not available", consult https://www.nomachine.com/AR11K00751