ufw

UFW(uncomplicated firewall) is the simple easy firewall to manage and protect your server. Few command snippets to manage it.

* View configured rules in ufw: It'll list all the allowed/rejected rules for ufw.
    * `sudo ufw status`
    * It might show **Status: inactive**. You need to enable ufw to view rules.

* View firewall added rules, while firewall is in **in-active state** or is not-enabled.
    * `ufw show added`

* Add a rule to firewall: It will allow the connection to machine given on specific port(here 7865).
    * `sudo ufw allow 7865/tcp`
    * `sudo ufw allow 22/tcp`

* Enable Ufw: By default ufw will be started on your machine, but **ufw itself will not be in enabled state**.
    * To enable it: `sudo ufw enable`

<hr/>
 <center>Remember to enable incoming ssh connection to machine, else you'll not be able to login to machine.</center>
 <hr/>

* Reject all connections to machine: It will implicitly reject all the connection, that are not allowed by the firewall.
    * `sudo ufw default reject incoming`

* To allow all outgoing connections. 
    * `sudo ufw default allow outgoing`


**References**

* [https://www.digitalocean.com/community/tutorials/how-to-setup-a-firewall-with-ufw-on-an-ubuntu-and-debian-cloud-server](https://www.digitalocean.com/community/tutorials/how-to-setup-a-firewall-with-ufw-on-an-ubuntu-and-debian-cloud-server)
* [https://askubuntu.com/questions/30781/see-configured-rules-even-when-inactive](https://askubuntu.com/questions/30781/see-configured-rules-even-when-inactive)