Working With Ubuntu Firewall

Ubuntu Firewall

1.Enable Disable firewall on Ubuntu 18.04

Check a current firewall status
$ sudo ufw status

Enable Firewall
$ sudo ufw enable

Disable Firewall 	 

$ sudo ufw disable
$ sudo ufw status

2.How to Enable SSH on Ubuntu 18.04
Secure Shell (SSH) is a cryptographic network protocol used for a secure connection between a client and a server.

In this tutorial, we’ll show you how to enable SSH on an Ubuntu Desktop machine. Enabling SSH will allow you to remotely connect to your Ubuntu machine and securely transfer files or perform administrative tasks.

Enabling SSH on Ubuntu
sudo apt update
sudo apt install openssh-server
sudo systemctl status ssh
sudo ufw allow ssh

sudo systemctl stop ssh

To start it again run:
sudo systemctl start ssh

To disable the SSH service to start during system boot run:
sudo systemctl disable ssh

To enable it again type:
sudo systemctl start ssh
sudo systemctl stop ssh
sudo systemctl restart ssh
sudo systemctl enable ssh
sudo systemctl status ssh

3. open 443 port on ubuntu 18.04

$ sudo ufw allow 80
$ sudo ufw allow 443
OR
$ sudo ufw allow http
$ sudo ufw allow https

$ sudo ufw delete allow 80
$ sudo ufw delete allow 443
OR
$ sudo ufw delete allow http
$ sudo ufw delete allow https

4.Allow incoming connection on terminal
sudo ufw allow ssh

Allow Specific incoming connection
sudo ufw allow http
sudo ufw allow https

The following command allows connections from ports 6000 to 6003 for both tcp and udp.
 sudo ufw allow 6000:6003/tcp
 sudo ufw allow 6000:6003/udp

Enable UFW
sudo ufw enable

check status of ufw
sudo ufw status