How to open basic ipv4 ports on ubuntu

Motivation

If you host a website you usually want to access it. To do this you need to open some ports. Here we’re using ufw for this purpose.

Opening ports

At first you need to login to your server via ssh for example with:

bash
ssh root@MY_IP

For this to work your ssh key has to be added to the authorized keys for the root user. As soon as you’re logged in you can call

bash
ufw status

Which might just tell you “Status: inactive”. This “ufw” thing is the firewall which we need to enable. 3 ports have to be able for us to use and maintain our application properly, namely 22 (ssh), 80 (http) and 443 (https). They all can differ depending on your preferences though. These are just the default ports. So we call the following to allow and enable them:

bash
ufw allow 22
ufw allow 80
ufw allow 443
ufw enable

We can see what this give us:

bash
ufw status
Status: active
To                         Action      From
--                         ------      ----
22                         ALLOW       Anywhere
80                         ALLOW       Anywhere
443                        ALLOW       Anywhere
22 (v6)                    ALLOW       Anywhere (v6)
80 (v6)                    ALLOW       Anywhere (v6)
443 (v6)                   ALLOW       Anywhere (v6)

Wrapping Up

Now as mentioned we opened the ssh port. Thats the “door” we’ve gone through to get to our server. So before closing the existing connection, it’s highly recommended that you try to log in from another terminal. If it doesn’t work, then you have now an easier time to correct this. Otherwise thing might look grim. That’s all there is to it. Short and simple. But there is of course a lot more to it. You can allow ports only for specific IPs or a explicitly define a TCP or UDP allowance.