how can i stop port scans, close open ports/stealth. & redirect traffic to another port. EL Capitan

hi everyone i have the latest os x EL Capitan 10.11.2 currently have avast anti virus & Little Snitch Firewall. i also have a netgear cg3000v2.
everytime i look at the logs on my router it always shows that the DNS from my Mac book has port scanned the defult gateway of my router. i no no port scans are good because they are exploiting vulnerabilities in my network. i no with a windows computer i'd be able to do a full scan of my network an see if there is some kind of bug in it. but there is nothing like that for a mac. so my question is does any one no why my DNS would be port scanning constantly. i have changed my dns a few times hoping that would work never does. i've used my isp, openDNS, google dns & norton dns. is there a way i can redirect the traffic from port 53 to another port to prevent port scans. thank you in advance for any help anyone might have about this issue, and if anyone knows of any network scan i can do from a mac please let me no. also is it normal for port 5000, 1900, 80, 443, 8889 to be open on my mac. is there anyway to close, or stealth ports on a mac. i do have the mac firewall on to block all incoming connections and stealth is on. but doesn't actually do nothing. i'm still currently learning a mac. i've had a windows computer all my life so not very fluent in the osx operating system yet.

sorry about any spelling mistakes & grammer mistakes.