A quick overview of the IP filter

Table of Contents

Learn All About IP filter

This open-source software package provides firewall functionality as well as network address translation to a number of Unix-like operating systems. FreeBSD, NetBSD, OpenBSD, and Solaris are all supported by this open-source firewall. As a kernel loadable module, IPfilter comes with the basic FreeBSD installation. 


The following tutorials will help you troubleshoot IPFilter by providing helpful commands and techniques.

So let’s get start,


Launch IPfilter 


# service ipfilter start

Check out the active packet filtering rules


# ipfstat -io

Remove all filtering rules from the ruleset


ipf -F a


Turn off IPfilter 

# service ipfilter stop

Simple tasks


Permitting SSH but denying everything else

Include the following in /etc/ipf.conf to set up a firewall that blocks everything except SSH on port 22. The example IP address is

block in on any all
pass in quick on any proto tcp from any to port = 22 keep state

That’s it, We hope this guide was informative for you.


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