ConfigServer Security & Firewall (CSF) is one of the most powerful, flexible, and widely used firewall suites for Linux servers. It offers advanced protection features with easy setup, especially on VPS and dedicated servers. Whether you're securing SSH, blocking brute force, or managing IP whitelists, CSF gives fine-grained control over server traffic.
Note: This tutorial is intended only for VPS or Dedicated Server environments.
Step-by-Step Guide to Installing CSF on Linux VPS
Step 1: Log in via SSH as root. Open your terminal and log in to your Linux server using the root user.
Step 2: Download the CSF installation package
# wget https://download.configserver.com/csf.tgz
Step 3: Extract the downloaded archive
# tar xfz csf.tgz
Step 4: Navigate to the CSF directory
# cd csf
Step 5: Run the CSF installer
# sh install.sh
The installer will generate the necessary configuration files and automatically add standard cPanel services to the allowlist. Once complete, you'll see something like:
TCP ports currently listening for incoming connections: 21, 22, 25, 53, 80, 110, 143, 443, 465, 993, 995, 2077, 2078, 2082, 2083, 2086, 2087, 2095, 2096, 3306 UDP ports currently listening for incoming connections:</strong 53, 123
Note: These are just listed ports. CSF is not auto-configured yet.
Post-Installation Configuration
Step 6: Update CSF Configuration. Edit the following settings in the CSF config file:
TCP_IN, TCP_OUT UDP_IN, UDP_OUT
Adjust them according to your server’s needs.
Step 7: Restart CSF and LFD
# systemctl restart csf # systemctl restart lfd
Step 8: Add your current SSH IP to the whitelist CSF adds your IP (e.g., 10.30.6.17) to the csf. Allow the file temporarily while in TESTING mode.
Disabling Testing Mode & Finalizing Setup
Step 9: Start CSF in testing mode
# systemctl start csf
Step 10: Edit the CSF config to disable testing. Open the config file in an editor (example: Nano):
# nano /etc/csf/csf.conf
Step 11: Find and edit the following line:
TESTING = "1" Change it to: TESTING = "0"
Save and exit the file.
Step 12: Restart CSF to apply changes
# systemctl restart csf
Conclusion:
CSF is now fully installed, configured, and running in production mode on your Linux VPS. This firewall now helps monitor open ports, manage IP traffic, and boost your server’s security posture—all while giving you control and flexibility.
