Ubuntu firewall settings

By default, ubuntu firewall provides a very good firewall tool (UFW). UFW is a host-side iptables firewall configuration tool. The purpose of this tool is to provide users with an interface that can be easily controlled, just like package integration and dynamic detection of open port 1... by default, ubuntu firewall provides a very good firewall tool (UFW), which is a host.
Iptables firewall configuration tool. The purpose of this tool is to provide users with an interface that can be easily controlled, just like package integration and dynamic detection of open ports. 1. port opening and shielding in ubuntu # ufw default allow | deny $ sudo ufw allow 22 open 22 Port $ sudo ufw deny 22 Shield 22 Port $ sudo ufw allow 22/tcp open TCP/IP 22 Port 2. delete an opened Port $ sudo ufw delete allow 22 3. set the default policy (for example, "mostly open" vs "mostly closed") # ufw default allow | deny $ sudo ufw default deny. by default, all ports are blocked. 4. view the firewall status $ sudo ufw status 5. enable or disable the firewall # ufw enable | disable $ sudo ufw enable the firewall $ sudo ufw disable