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Linux remote access using NX

Introduction

The NX technology from NoMachine allows fast remote desktop session over small-bandwidth connections. The performance is even better then RDP, the remote desktop technology used in Microsoft Windows.

A normal modem connections appears to be sufficient for NX access. The NX servers also allow sessions to disconnect and re-connect later.

NX Free Edition

The NX Free Edition can be installed at any Linux system. After installing the packages, the other clients should be able to connect.

After installation, it's recommended to change the default key, and add a few system users only. Useful commands are:

Useful nxserver commands:
nxserver --useradd      # add a user
nxserver --userenable   # enable an existing usre
nxserver --list         # list all users
nxserver --keygen       # generate a unique SSH key, required to connect
nxserver --keyrestore   # restore the default key, included with all clients.

Background

An NX connection is established in two steps.

First, a connection is made using SSH. The client connects with the username 'nx', and uses publickey authorization to login.

The 'nx' user does not have a normal shell, but a NX command prompt. From this prompt, the client authenticates itself with the NX server. The remote display is opened.

This technique gives the NX server full control over whom may login, while staying secure too. An NX server installation is always as secure as the respective SSH installation. The only weak link in this mechanism is the default key used to access the 'nx' account. To improve security, it's recommended to replace the default key with your own.

After the login process completed, the remote desktop session is started.

External Links

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