With the release of NoMachine 6, the following Feature Request was implemented:
Dropping support for 'NoMachine login' method
This means that starting from version 6 the '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 not offer the option to enable the 'NoMachine login' method.