Configuring the Linux Firewall with UFW
Uncomplicated Firewall (UFW) is a convenient command-line tool for handling Debian-based Linux firewall policies. The following procedure will set up UFW to block unauthorized remote access to any unsecured ports on the server. And if remote attackers do manage to break in through some authorized incoming ports, the outgoing restrictions will prevent unauthorized massive data exfiltration, stopping intruders dead in their tracks. A similar technique can be applied on the FreeBSD operating system using IPFW . ========== 1. STRICT CONFIGURATION 1.1. Update the package list and upgrade the existing packages. user@host: $ sudo apt-get update && sudo apt-get dist-upgrade -y 1.2. Install UFW. user@host: $ sudo apt-get install ufw 1.3. Check the firewall settings. The firewall is usually disabled by default. user@host: $ sudo ufw status verbose 1.4. Open the port for incoming SSH. This ensures that administrators will not be locked out of the server when the f...