How to find culprit blocking TCP ports 80, 443, and 5223 on macOS? These ports, crucial to iMessage and Facetime, are blocked: TCP Ports 80, 443, and 5223 on macOS Sierra 10.12.2 (MacBookPro11,3). (https://support.apple.com/en-us/HT202078)

In Network Utility, I perform a scan and the only Open Port is 631. 

When I run:

python -m SimpleHTTPServer 80


I get a few calls then it reads that:


  socket.error: [Errno 13] Permission denied


A few other terminal commands return similar responses.

Is there a method I can use to find the culprit that is blocking these ports (and likely others) on OSX? These ports specifically are needed for iMessage and Facetime. 

I do not have Sophos or any other Firewall (that I know of).
There are two things you confuse:


FaceTime and iMessage require communication on ports specified in the article for outbound connections.
Your "Permission denied" message is related to opening the port 80 for inbound connections. It's not because of any process blocking it, but if you want to make a process listen on a port less than 1024, you need to use root, so:

sudo python -m SimpleHTTPServer 80