Reminders about Ports

If you open a port for port forwarding, 2222 in my example, you will also need to remember to open it on your firewall as well, otherwise, it will be blocked before it can be forwarded.
Also, any time that you need to specify a source or destination port (--sport and --dport respectively) in a rule, make sure you remember to specify the source or destination address (-s and -d respectively) and protocol type (-p). This is important, because otherwise the iptables syntax will give you an error. This should be easy to see later in the script.

If you open a port for port forwarding, 2222 in my example, you will also need to remember to open it on your firewall as well, otherwise, it will be blocked before it can be forwarded.