What is APF (Advanced Policy Firewall)? APF Firewall

Posted by at 20 July, at 15 : 05 PM Print

What is APF (Advanced Policy Firewall)? APF 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.

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-0.9.5-1/ or whatever the latest version is.

5. Run the install file: ./install.sh
You will receive a message saying it has been installed

Installing APF 0.9.5-1: Completed.

Other Details:
Listening TCP ports: 1,21,22,25,53,80,110,111,143,443,465,993,995,2082, 2083,2086,2087,2095,2096,3306
Listening UDP ports: 53,55880
Note: These ports are not auto-configured; they are simply presented for information purposes. You must manually configure all port options.

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=”21,22,25,53,80,110,143,443,2082,208 3, 2086,2087, 2095, 2096,3000_3500″
#
# Common ingress (inbound) UDP ports
IG_UDP_CPORTS=”53″

Common egress (outbound) ports
# Egress filtering [0 = Disabled / 1 = Enabled]
EGF=”1″

# 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″

8. Starting the firewall
/usr/local/sbin/apf -s

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″

10. Configure AntiDOS for APF
Relatively new to APF is the new AntiDOS feature which can be found in: /etc/apf/ad
The log file will be located at /var/log/apfados_log so you might want to make note of it and watch it!

pico /etc/apf/ad/conf.antidos

11. Checking the APF Log

tail -f /var/log/apf_log

12. New – Make APF Start automatically at boot time

chkconfig –level 2345 apf on

To remove it from autostart, run this:

chkconfig –del apf

13. Denying IPs with APF Firewall (Blocking)

Pico /etc/apf/deny_hosts.rules

You can then just add a new line and enter the IP you wish to block. Before this becomes active though you’ll need to reload the APF ruleset.

/etc/apf/apf -r

14. Allowing IPs with APF Firewall (Unblocking)

I know I know, you added an IP now you need it removed right away! You need to manually remove IPs that are blocked from deny_hosts.rules.

pico /etc/apf/deny_hosts.rules

Find where the IP is listed and remove the line that has the IP.
After this is done save the file and reload apf to make the new changes active.

/etc/apf/apf -r

pico /etc/apf/allow_hosts.rules

# added 185.14.157.123 on 08/23/05 01:39:43
# UNBLOCKING
185.14.157.123

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