Starting from version 6 the SSH protocol + 'NoMachine login' authentication method is no longer an option in the NoMachine User Interface nor a configuration available in the NoMachine Server.

Since version 4 was released, NoMachine has continued to support more and more authentication options in order to offer the most flexible and most secure integration with existing configurations available on the server host. This has allowed administrators to progressively move away from the 'NoMachine login' option to methods which integrate much more transparently with their production environments, thus requiring fewer configurations and QoS testing.

Dropping support for the 'NoMachine login' not only affects all servers using such method. It also means that compatibility with legacy version 3.5 is no longer available. Thus, any NoMachine Server version 6 or later will not accept connections from client version 3.x, and client version 6 or later will benot able to connect to NX servers v. 3. This means that legacy versions NX 3.x cannot be used with NoMachine v. 6 or later.