apt update -y

optional:

apt upgrade -y

add a new user netsec which later you can use it to log in

adduser netsec

Enable Password Log In  (Optional)

By default, Oracle vm is using certificate to log in and password login has been disabled.

nano /etc/ssh/sshd_config

comment the line

#PasswordAuthentication no

Install Desktop

There are various desktop environments available in Ubuntu repositories that you can choose. One option is to install Gnome, which is the default desktop environment in Ubuntu 20.04. Another option is to install Xfce . It is a fast, stable, and lightweight desktop environment, which makes it ideal for usage on a remote server.

Run one of the commands below to install the desktop environment of your choice.

• Install Gnome:

  apt install ubuntu-desktop -y

Depending on your system, downloading and installing GUI packages will take some time.

Install and Configure xRDP

Xrdp is incuded in the default Ubuntu repositories. To install it, run:

apt install xrdp -y

Once the installation is complete, the Xrdp service will automatically start. You can verify it by typing:

systemctl status xrdp

Enable 3389 port on IPv4 interface. For somehow, the default configuration, port=3389, which will cause 3389 port running on inet6 interface. You can verify port running status from following two commands

• apt install net-tools
• netstat -na | grep 3389

To change the configuration, edit xrdp.ini file using following command:

sudo nano /etc/xrdp/xrdp.ini

Reboot the service to take the configuration change into effect.

• systemctl restart xrdp

Allow Port 3389 from Oracle NSG (Network security group)

Don’t forget to add inbound rule into your network security group to allow tcp port 3389.

Remove Built-in Firewall Rules – iptable

Even you have added 3389 port in Oracle NSG, if you are using Oracle’s Ubuntu image, you will still have connectivity issue to the port 3389 since built-in iptables will block the external connection. Testing from local will still work, but not from remote.

Default output is:

Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

MSTSC (RDP Client) Log in

Issues

I found another annoying thing which this desktop has no sound forwarding from remote to my local computer with RDP connection.

root@ubuntu-arm-xrdp:~# history
    1  apt update -y
    2  adduser netsec
    3  apt install ubuntu-desktop -y && apt install xrdp -y
    4  systemctl status xrdp
    5  netstat -nat | grep 3389
    6  apt install net-tools
    7  netstat -nat | grep 3389
    8  nano /etc/xrdp/xrdp.ini
    9  systemctl restart xrdp
   10  netstat -nat | grep 3389
   11  telnet localhost 3389
   12  iptables -list
   13  iptables --L
   14  clear
   15  iptables -L
   16  iptables -F
   17  iptables -L
   18  netfilter-persistent save
   19  history
root@ubuntu-arm-xrdp:~#

To make the configuration steps much simple, here is the a script which includes all commands you will need it to get sound working in xRDP environment.

wget https://cdn.jsdelivr.net/gh/51sec/xrdp4arm@main/install_xrdp_audio.sh && bash install_xrdp_audio.sh