To start iodined at boot, put these lines to your rc.conf:

  iodined_enable="YES"
  iodined_password="Passw0rd"         # tunnel password
  iodined_domain="t.example.net"      # tunnel domain

Note that the password is visible from process list. The default ip
on the tunnel interface is set to 172.16.0.1. You can change it with
the ``iodined_addr'' variable in rc.conf.

You need to delegate the tunnel domain for iodined use. Add things
like these to the DNS zone file:

  iodined	IN	A	192.0.2.1
  t		IN	NS	iodined.example.net.

Replace 192.0.2.1 with your server's (the one you run iodined) IP.

To run the client,

  iodine -f -u _iodined -t /var/empty 192.168.1.1 t.example.net

Replace 192.168.1.1 with your DNS server.

See iodine(1) for more information.