On Windows servers, opening ports is as easy as configuring your Win Firewall to accept the connection. Well here's a guide to do that:
https://www.google.com/amp/s/www.paralle...llels-ras/.
As I'd already mentioned, on Linux xrdp is a great one, for which you'll need to open 3389. It depends on the firewall you're using, whether its FirewallD for CentOS 7, iptables for CentOS 6 or earlier, ufw, or if you've VestaCP installed, then it'll be the Vesta Firewall for you where you can open the port through the web interface.
For your reference, here's how to open ports on various firewalls:
For FirewallD:
$ sudo firewall-cmd --zone=public --add-port=80/tcp --permanent
$ sudo firewall-cmd --reload
For iptables:
sudo iptables -I INPUT -p tcp -m tcp --dport 80 -j ACCEPT
$ sudo service iptables save
For UFW, check @
LightDestory's post here:
https://post4vps.com/Thread-Setting-up-a...rewall-UFW
For opening port on VestaCP through Web Interface, check my post here:
https://post4vps.com/Thread-Change-VestaCP-Port
Hope this helps you!
Cheers!