[Basic] "Forward" a port with UFW in Ubuntu 18.04 Linux

In this guide, we're going to briefly cover how to do a basic "port forward" with UFW.

The example we're going to use is forwarding traffic from your server's port 80 to a custom defined port. In this instance, our web server is set to only listen to traffic on port 8080, and we want our users to be able to access it by simply using the domain name without a port in the address bar (such as www.domain.tld)

First, we allow the port in UFW. (We're going to toss in a rule for ssh as a good measure just in case it wasn't set beforehand. This way we don't lose access to the server when re-enabling UFW)

sudo ufw allow 8080/tcp
sudo ufw allow ssh

sudo nano /etc/ufw/before.rules

*nat
:PREROUTING ACCEPT [0:0]
-A PREROUTING -p tcp --dport 80 -j REDIRECT --to-port 8080
COMMIT

sudo ufw disable

sudo ufw enable