What is APF (Advanced Policy Firewall)? APF is a policy based iptables firewall system designed for ease of use and configuration. It employs a subset of features to satisfy the veteran Linux user and the novice alike. Packaged in tar.gz format and RPM formats, make APF ideal for deployment in many server environments based on Linux. APF is developed and maintained by R-fx Networks: http://www.rfxnetworks.com/apf.php This guide will show you how to install and configure APF firewall, one of the better known Linux firewalls available. Requirements: - Root SSH access to your server Lets begin! Login to your server through SSH and su to the root user. 1. cd /root/downloads or another temporary folder where you store your files. 2. wget http://www.rfxnetworks.com/downloads/apf-current.tar.gz 3. tar -xvzf apf-current.tar.gz 4. cd apf-0.9.3_3/ or whatever the latest version is. 5. Run the install file: ./install.sh You will receive a message saying it has been installed .: APF installed Install path:    /etc/apf Config path:     /etc/apf/conf.apf Executable path: /usr/local/sbin/apf 6. Lets configure the firewall: pico /etc/apf/conf.apf We will go over the general configuration to get your firewall running. This isn't a complete detailed guide of every feature the firewall has. Look through the README and the configuration for an explanation of each feature. We like to use DShield.org's "block" list of top networks that have exhibited suspicious activity. FIND: USE_DS="0" CHANGE TO: USE_DS="1" 7. Configuring Firewall Ports: Cpanel Servers We like to use the following on our Cpanel Servers Common ingress (inbound) ports # Common ingress (inbound) TCP ports -3000_3500 = passive port range for Pure FTPD IG_TCP_CPORTS="21,22,25,53,80,110,143,443,2082,2083, 2086,2087, 2095, 2096,3000_3500" # # Common ingress (inbound) UDP ports IG_UDP_CPORTS="53" Common egress (outbound) ports # Common egress (outbound) TCP ports EG_TCP_CPORTS="21,25,80,443,43,2089" # # Common egress (outbound) UDP ports EG_UDP_CPORTS="20,21,53" Ensim Servers We have found the following can be used on Ensim Servers - although we have not tried these ourselves as I don't run Ensim boxes. Common ingress (inbound) ports # Common ingress (inbound) TCP ports IG_TCP_CPORTS="21,22,25,53,80,110,143,443,19638" # # Common ingress (inbound) UDP ports IG_UDP_CPORTS="53" Common egress (outbound) ports # Common egress (outbound) TCP ports EG_TCP_CPORTS="21,25,80,443,43" # # Common egress (outbound) UDP ports EG_UDP_CPORTS="20,21,53" Save the changes: Ctrl+X then Y 8. Starting the firewall /usr/local/sbin/apf -s Other commands: usage /usr/local/sbin/apf [OPTION] -s|--start ............. load firewall policies -r|--restart ........... flush & load firewall -f|--flush|--stop ...... flush firewall -l|--list .............. list chain rules -st|--status ........... firewall status -a HOST|--allow HOST ... add host (IP/FQDN) to allow_hosts.rules and                          immediately load new rule into firewall -d HOST|--deny HOST .... add host (IP/FQDN) to deny_hosts.rules and                          immediately load new rule into firewall 9. After everything is fine, change the DEV option Stop the firewall from automatically clearing itself every 5 minutes from cron. We recommend changing this back to "0" after you've had a chance to ensure everything is working well and tested the server out. pico /etc/apf/conf.apf FIND: DEVM="1" CHANGE TO: DEVM="0" Save your changes! Ctrl+X then press Y Restart the firewall: /usr/local/sbin/apf -r 10. New - Make APF Start automatically at boot time To autostart apf on reboot, run this: chkconfig --level 2345 apf on To remove it from autostart, run this: chkconfig --del apf Thanks to R-fx networks for developing and maintaining this product.