FreeBSD.org: Dialup firewalling with FreeBSD

“This document aims to cover the process that is required in
order to setup firewalling with FreeBSD when are dynamically
assigned an IP address by your ISP. While every effort has
been made to make this document as informative and correct as
possible, you are welcome to mail your comments/suggestions to the
maintainer….”

“We’re nearly done now. All that remains now is to define the
firewall rules and then we can reboot and the firewall should be up
and running. I realise that everyone will want something slightly
different when it comes to their rulebase. What I’ve tried to do is
write a rulebase that suits most dialup users. You can obviously
modify it to your needs by simply using the following rules as the
foundation for your own rulebase. First, let’s start with the
basics of closed firewalling. What you want to do is deny
everything by default and then only open up for the things you
really need. Rules should be in the order of allow first and then
deny. The premis is that you add the rules for your allows, and
then everything else is denied. :)”

“Now, let’s make the dir /etc/firewall. Change into the
directory and edit the file fwrules as we specified in rc.conf.
Please note that you can change this filename to be anything you
wish. This guide just gives an example of a filename.”

Complete
Story