This requires no port forwarding, so someone brute force scanning your IP won't find this and your open port. they also might have a harder time figuring out what service has been exposed since the port number itself will be unknown.

If somebody learns that such-and-such DynDNS URL is mine, they can always do a DNS lookup to find my current IP address. They can:

- find my approximate physical location

- regularly scan ports on my IP and wait for me to accidentally expose a service I didn't mean to

- track me in any access logs they have access to