port 7547 open

[Jim Byrnes]

Using Ubuntu 14.04
Using an Xfinity Gateway - voice-internet-wireless

While reading an article on the recent ddos attacks I came across 
mention of this service http://iotscanner.bullguard.com/search.

I connected to it and ran the scan and it said I was public on Shodan 
and my network was reachable through port 7547. I tried another service 
and it also said port 7547 was open.  Reading up on port 7547 shows

Protocol = tcp,udp
Service = cwmp
Details - DSL Forum CWMP
Source = IANA

So I guess my questions are:

How much of a threat is this?
How can I see what ports are open?
How can close a port if needed?

Thanks,  Jim