ubuntu18 firewall related operations

1. Install a firewall

 apt-get install ufw 

2. Enable the firewall

 ufw enable 

3. Disable the firewall

 ufw disable  

4. View firewall status

 ufw status 

5. Allow external access to port 80

 ufw allow 80 

6. Delete the added rule

 ufw delete allow 80 

7. Allow this ip to access all ports of this machine

 ufw allow from 192.168.0.105 

8. Prohibit the port

 uwf deny service (port)

9. View port status

 lsof -i: port number  

 

Recommended settings

APT- GET install ufw 
ufw enable 
ufw default deny 

# If you have special needs, to enable the service 
ufw allow port