Remote Desktop Connection not working - not enabled or not available

I'm using Ubuntu 18.04

I tried installing xrdp but it didn't work.

I used some methods like

1. apt-get install xrdp apt-get install xfce4 apt-getecho xfce4-session >~/.xsession

2. install xrogxrdp

3. install tightvncserver

4. install gnome-session

and I tried some more other processes but they didn't work and i have tried enabling the respective port for xrdp xorg.

root@incrcomnetpp:/home/abb# netstat -lntp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:139             0.0.0.0:*               LISTEN      1925/smbd    
tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      704/systemd-resolve
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      1393/sshd    
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN      5725/cupsd   
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      1996/master  
tcp        0      0 0.0.0.0:445             0.0.0.0:*               LISTEN      1925/smbd    
tcp        0      0 127.0.0.1:8000          0.0.0.0:*               LISTEN      1338/gen4agent-linu
tcp        0      0 127.0.0.1:8009          0.0.0.0:*               LISTEN      1338/gen4agent-linu
tcp6       0      0 :::139                  :::*                    LISTEN      1925/smbd    
tcp6       0      0 :::22                   :::*                    LISTEN      1393/sshd    
tcp6       0      0 ::1:3350                :::*                    LISTEN      1365/xrdp-sesman
tcp6       0      0 ::1:631                 :::*                    LISTEN      5725/cupsd   
tcp6       0      0 ::1:25                  :::*                    LISTEN      1996/master  
tcp6       0      0 :::445                  :::*                    LISTEN      1925/smbd    
tcp6       0      0 :::3390                 :::*                    LISTEN      1399/xrdp    

root@incrcomnetpp:/home/abb# iptables-save | grep 5900
-A ufw-user-input -p tcp -m tcp --dport 5900 -j ACCEPT
-A ufw-user-input -p udp -m udp --dport 5900 -j ACCEPT
root@incrcomnetpp:/home/abb# iptables-save | grep 5901
-A ufw-user-input -p tcp -m tcp --dport 5901 -j ACCEPT
-A ufw-user-input -p tcp -m multiport --dports 5901:5910 -j ACCEPT
root@incrcomnetpp:/home/abb# iptables-save | grep 3389
-A ufw-user-input -p tcp -m tcp --dport 3389 -j ACCEPT
-A ufw-user-input -p tcp -m tcp --dport 3389 -j ACCEPT
-A ufw-user-input -p udp -m udp --dport 3389 -j ACCEPT

You can find out if it is application issue or network connection issue. I suggest list of checks. Begin on device which should be managed remotely:

1. Is application TCP port listening?

Install net-tools if not installed: sudo apt-get install net-tools and use netstat for first check:

sudo netstat -lntp

Search for listening port. Application/service name is in last column of command response. Typical TCP ports are: 5900 or 5901... for VNC, 3389 for RDP etc. Port numbers are in third column after colon, eg. 0.0.0.0:5900

If no remote access listening port is opened, it is usually application setting problem or service is not started. Check logs in /var/log/ and service status.

2. Does your firewall allow incomming connection?

sudo iptables-save
sudo iptables-save | grep <a TCP port number>

First command displays details about local firewall. If no output is visible it means firewall is not active. No action is needed. Go to step #3.

In case some lines are listed you can filter them by second command. Replace <a TCP port number> by your real port number (e.g. 5900) from step #1 explained above. If your port is not listed with ACCEPT clause at end of line, you must open the port in firewall. There are more possibilities how to do it, I do not know what kind of firewall management do you use (iptables only, UFW, GUFW...).

3. Is your Ubuntu 18.04 system reachable from another PC via network?

ip address show
ip a

Second command is short version of first one. Use this command on both sides, i.e. in Ubuntu 18.04 (PC-A) and in another PC (PC-B) from which you will try to connect remotely to PC-A. Search for their IP addresses.

Put command in PC-B:

ping <PC-A IP address>

If you see positive ping response (response time in miliseconds) from PC-A, the PC-A is reachable in network. In case none or negative response is displayed you must solve network connection issue.

Put command in PC-B:

telnet <PC-A IP address> <a TCP port number>

where <a TCP port number> is listening port from step #1. If response is "Connected to .." you verified the PC-A is reachable for remote access.

If response is "telnet: Unable to connect to remote host: Connection refused" or no response for a long time, it means some blocking point is between PC-B and PC-A.

If the PC-B operating system is Windows, then telnet is not available by default. You must install it by adding feature to Window system (Control Panel, Uninstall or change a program, Turn Windows features on or off, search for Telnet client, enable it).

4. Do you use correct remote access application and port on PC-B?

It is next possible problem source. Install and try a Remmina application on PC-B. It is useful and universal. It can be used for VNC, RDP, SSH... type of access. Be careful concerning TCP port you use. In case PC-A is listening on 5901, you cannot use default 5900 port in VNC access. Etc.

If the PC-B operating system is Windows, use mstsc command instead of the Remmina.