http://gpp6nwvsps43b3mfacsh433uroo6uyjvvpr6tgj4jh4n5ngxt7rqbvid.onion/posts/iodine-dns-tunnel-port-53.html
The Iodine documentation implies that Iodine only actually uses 53/udp , but we will open both. The actual DNS protocol requires 53/tcp to be available as a backup in case 53/udp fails. We also need to open the firewall for SSH input from the virtual network, for which we use IP addresses 10.10.0.0/24 in the examples in this article.