Firewall

Check the service status with standard systemctl command:

$ sudo systemctl status ufw 


Enable UFW with enable command:

$ sudo ufw enable

 
Syntax to open specific TCP port:

$ sudo ufw allow (port)/tcp

 

Syntax supports also names which reffer to specific ports:

$ sudo ufw allow https

 

To allow incoming tcp and udp packet on port 21, enter:

$ sudo ufw allow 21

 

Example for specific IP Address:

$ sudo ufw allow from 190.34.21.113 to any port

 

Let’s check the configuration:

$ sudo ufw status verbose

To open a specific port
$ iptables -A INPUT -p tcp -i eth0 --dport 80 -j ACCEPT

$ firewall-cmd --zone=public --add-port=3306/tcp --permanent
$ firewall-cmd --reload