Initially I just want to open a port on the firewall, but there doesn't seem to be any obvious way to do that.
Ubuntu ships with no open network ports, but ports are opened by applications so if you have installed or enabled network services (network file sharing, web servers, ssh, remote desktop, etc), then you may have open ports.
Open a terminal session (control alt f2) and after you paste this it will show you open ports:
sudo netstat -ntlup
From the UFW wiki page.
The easiest way to close ports is to use
ufw. This will show if
ufw is active:
sudo ufw status
(by default it is active).
To allow incoming tcp and udp packet on port 53
sudo ufw allow 53
To deny tcp and udp packets on port 53
sudo ufw deny 53
Ubuntu Tweak is a tool someone created that adds lots of settings. More info here.
You can install it with these commands:
sudo add-apt-repository ppa:tualatrix/ppa
sudo apt-get update
sudo apt-get install ubuntu-tweak
But ... I would advice to ask more about specific settings. Mosttimes it is easier just to open a text file and edit that. After you are a command line junkie like some of us you will be a lot quicker setting up a system than with any GUI.
Rightclick your network connection at the top right. It will have a properties option with all settings for networking.