How to block IP address with pf on FreeBSD, NetBSD and OpenBSD

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I’ve noticed some IPs which had a kind of too agressive behaviour towards my Apache webserver and thus decided to filter them out with the Firewall.
As the server is running FreeBSD and my firewall choise is bsd’s pf I added the following lines to my /etc/pf.conf to filter up the abiser IP:

table persist file "/etc/pf.blocked.ip.conf"
EXT_NIC="ml0" # interface connected to internet
block drop in log (all) quick on $EXT_NIC from to any
echo '123.123.123.123' >> /etc/pf.blocked.ip.conf

As you see I’m adding the malicious IP to /etc/pf.blocked.ip.conf, if I later decide to filter some other IPs I can add them up there and they will be loaded and filtered by pf on next pf restart.

Next I restarted my pf firewall definitions to make the newly added rules in pf.conf to load up.

freebsd# pfctl -d
freebsd# pfctl -e -f /etc/pf.conf

To show all IPs which will be inside the blockips filtering tables, later on I used:

pfctl -t blockips -T show

I can also later use pf to add later on new IPs to be blocked without bothering to restart the firewall with cmd:

freebsd# pfctl -t blockedips -T add 111.222.333.444

Deleting an IP is analogous and can be achieved with:

freebsd# pfctl -t blockedips -T delete 111.222.333.444

There are also logs stored about pf IP blocking as well as the other configured firewall rules in /var/log/pflog file.
Hope this is helpful to somebody.

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2 Responses to “How to block IP address with pf on FreeBSD, NetBSD and OpenBSD”

  1. Esther Barnas says:

    I have been examinating out some of your articles and i must say pretty clever stuff. I will definitely bookmark your website.

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