Update NoMachine docs

pages/merlin6/02-How-To-Use-Merlin/nomachine.md

@@ -21,77 +21,62 @@ Linux, the NoMachine client can be downloaded from https://www.nomachine.com/.
 
 ## Accessing Merlin6 NoMachine from PSI
 
-The Merlin6 NoMachine service is located **only** in the following login nodes:
+The Merlin6 NoMachine service is hosted in the following machine:
+
+* `merlin-nx.psi.ch`
+
+This is the **front-end** (hence, *the door*) to the NoMachine **back-end nodes**, 
+which contain the NoMachine desktop service. The **back-end nodes** are the following:
 
 * `merlin-l-001.psi.ch`
 * `merlin-l-002.psi.ch`
 
+Any access to the login node desktops must be done through **`merlin-nx.psi.ch`** 
+(or from **`rem-acc.psi.ch -> merlin-nx.psi.ch`** when connecting from outside PSI). 
+
+The **front-end** service running on **`merlin-nx.psi.ch`** will load balance the sessions 
+and login to any of the available nodes in the **back-end**.
+
+**Only 1 session per back-end** is possible.
+
 Below are explained all the steps necessary for configuring the access to the 
 NoMachine service running on a login node.
 
 ### Creating a Merlin6 NoMachine connection
 
-#### Creating a **New** connection
+#### Adding a new connection to the front-end
 
-Click on the **New** button to create a new connection:
+Click the **Add** button to create a new connection to the **`merlin-nx.psi.ch` front-end**, and fill up
+the following fields:
+* **Name**: Specify a custom name for the connection. Examples: `merlin-nx`, `merlin-nx.psi.ch`, `Merlin Desktop`
+* **Host**: Specify the hostname of the **front-end** service: **`merlin-nx.psi.ch`**
+* **Protocol**: specify the protocol that will be used for the connection. *Recommended* protocol: **`NX`**
+* **Port**: Specify the listening port of the **front-end**. It must be **`4000`**.
 
-![Create New NoMachine Connection]({{ "/images/NoMachine/screen_nx1.png" }})
+![Create New NoMachine Connection]({{ "/images/NoMachine/screen_nx_connect.png" }})
-
-#### Configuring **NX** protocol
-
-![Select NoMachine Protocol]({{ "/images/NoMachine/screen_nx2.png" }})
-
-#### Configuring NoMachine Server Information
-
-Select the corresponding login node server where the NoMachine service is running and
-keep **4000** as the listening port; then **Continue**. 
-
-![Configure NoMachine Server Information]({{ "/images/NoMachine/screen_nx3.png" }})
 
 #### Configuring NoMachine Authentication Method
 
+Depending on the client version, it may ask for different authentication options. 
+
 Choose your authentication method and **Continue**. **Password** or *Kerberos* are the recommended ones:
 
 ![Configure NoMachine Authentication Method]({{ "/images/NoMachine/screen_nx4.png" }})
 
-#### Configuring Proxy
+### Opening NoMachine desktop sessions
 
-In Merlin6, we will check **Don't use a proxy**, and **Continue**:
+By default, when connecting to the **`merlin-nx.psi.ch` front-end** it will automatically open a new
+session if none exists. 
 
-![Configure NoMachine Proxy Information]({{ "/images/NoMachine/screen_nx5.png" }})
+If there are existing opened sessions, instead of opening a new session, the screen in the below image.
+Users can reconnect to any existing session by clicking to the proper icon.
 
-#### Configuring Connection Name
+![Open an existing Session]({{ "/images/NoMachine/screen_nx_existingsession.png" }})
 
-We strongly recommend to add the login node hostname, but
+Users can also create a second session by clicking on the **`New Session`** button (*red* rectangle in the 
-you are free to choose any other name for your connection:
+below image.
 
-![Configure Connection Name]({{ "/images/NoMachine/screen_nx6.png" }})
+![Open a New Session]({{ "/images/NoMachine/screen_nx_newsession.png" }})
-
-### Connecting to Merlin6 NoMachine
-
-#### Opening an existing NoMachine connection
-
-Double click on the NoMachine server in order to connect to it:
-
-![Connect to a NoMachine existing connecion]({{ "/images/NoMachine/screen_nx7.png" }})
-
-#### Authenticating (whenever necessary)
-
-If authentication is required, you will be asked for it. The example below corresponds to **Password** 
-authentication:
-
-![NoMachine Authentication]({{ "/images/NoMachine/screen_nx8.png" }})
-
-#### Creating/Re-Connecting Virtual Desktops
-
-Finally, create a virtual desktop in order to get in. If a previous virtual desktop was created, you 
-might be able to re-attach the session. 
-
-![Create or Connect to a NoMachine Virtual Session]({{ "/images/NoMachine/screen_nx9.png" }})
-
-Some hints of how to manage the resolution and windows will be shown.
-
-![NoMachine Resolution/Window Management Hints]({{ "/images/NoMachine/screen_nx10.png" }})
 
 ### NoMachine LightDM Session Example
 
@@ -106,7 +91,7 @@ X Windows:
 
 Access to the Merlin6 NoMachine service is possible without VPN through **'rem-acc.psi.ch'**.
 Please follow the steps described in [PSI Remote Interactive Access](https://www.psi.ch/en/photon-science-data-services/remote-interactive-access) for
-remote access to the Merlin6 NoMachine services. Once logged in **'rem-acc.psi.ch'**, you must then login to one of the available MErlin6 NoMachine
+remote access to the Merlin6 NoMachine services. Once logged in **'rem-acc.psi.ch'**, you must then login to the **`merlin-nx.psi.ch` front-end** .
 services.
 
 ### VPN access