Fixes #21485: document in the getting started that virtualbox needs a…

… list of authorized IP

src/get-started/modules/ROOT/pages/environment/index.adoc

@@ -21,7 +21,8 @@ and more. You will need:
 * https://www.virtualbox.org/wiki/Downloads[VirtualBox], to run the demo virtual machines
 * https://www.vagrantup.com/downloads.html[Vagrant], to handle the virtual machines configuration and provisioning
 
-To instal them, run:
+
+To install them, run:
 
 * `sudo apt install -y virtualbox vagrant` on Debian/Ubuntu systems
 * `sudo yum install -y VirtualBox vagrant` on RHEL systems
@@ -42,6 +43,20 @@ vagrant up
 
 This will download the virtual machine image if needed, and will setup a Rudder environment using two virtual machines.
 
+[NOTE]
+
+====
+
+With recent VirtualBox, you need to defined the https://www.virtualbox.org/manual/ch06.html#network_hostonly[authorized IP range] for created boxes. Boxes created with this method use networks from 192.168.42.0/24 and upward, incrementing with each new environment running.
+
+To define this range, you need to create or edit as root file `/etc/vbox/networks.conf` to add
+
+----
+* 192.168.0.0/16
+----
+
+====
+
 [TIP]
 
 .Vagrant commands