tunnels IP packets over DNS, allowing them to be sent to a server without
any protocols other than DNS being used.
takes the following options:
The domain that nstxcd will send requests to. This domain must be delegated
to a machine that is running nstxd.
The IP address of a DNS server that can be reached from the current machine.
should be run against a domain that has been delegated to a machine running
nstxd. It will then take any packets that are sent to the tun0 interface and
send them over DNS to the other tunnel endpoint. Responses will appear on
the tun0 interface.