Configuring a DHCP server on FreeBSD

First, I had to install a suitable DHCP server:

# pkg install isc-dhcp44-server

Now enable it at boot time:

# cat >> /etc/rc.conf
dhcpd_enable="YES"
dhcpd_flags="-q"
dhcpd_conf="/usr/local/etc/dhcpd.conf"
dhcpd_ifaces="re0"
dhcpd_withumask="022"
^d

And write out a suitable configuration file:

# cat > /usr/local/etc/dhcpd.conf
option domain-name "home.fwaggle.org";
option domain-name-servers 10.0.0.1;

default-lease-time 600;
max-lease-time 7200;

authoritative;
ddns-update-style interim;
update-static-leases on;

subnet 10.0.0.0 netmask 255.0.0.0 {
	range 10.0.1.1 10.0.1.254;
	option routers 10.0.0.1;
}

key dhcpupdate {
		algorithm hmac-md5;
		secret SUPER_SECRET_KEY==;
}

zone home.fwaggle.org {
		primary 10.0.0.1;
		key dhcpupdate;
}

zone 10.in-addr.arpa {
		primary 10.0.0.1;
		key dhcpupdate;
}

group {
	use-host-decl-names on;
	option domain-name "home.fwaggle.org";
	ddns-domainname "home.fwaggle.org";

	include "/usr/local/etc/static-leases.conf";
}
^d

I generate static-leases.conf with this script:

#! /bin/sh

echo -n '' > static-leases.conf

while read line
do
	host=$(echo "$line" | awk '{ print $1 }')
	ip=$(echo "$line" | awk '{ print $3 }')
	mac=$(echo "$line" | awk '{ print $2 }')

	if [ "$host" != "" ]
	then
		echo -n "	host $host { " >> static-leases.conf
		echo -n "hardware ethernet $mac; " >> static-leases.conf
		echo -n "fixed-address $ip; " >> static-leases.conf
		echo "}" >> static-leases.conf
	fi
done < static-leases.txt

But you can specify static host entries yourself fairly easy:

	host fwaggle-desktop { hardware ethernet 2c:4d:54:d5:a5:da; fixed-address 10.0.0.2; }

Now start the DHCP server:

# service isc-dhcpd start

… and go try one of your devices which is not configured for a static IP - make sure there are no other DHCP servers on your LAN. Check /var/log/messages for any issues with Dynamic DNS, it should work as configured but I did a terrible job of documenting that portion.