Macos – How to close a port (seen open on netstat)

Looking at your output, I don't think those are MAC addresses. Rather they are IPv6 addresses. Also, I think the carriage returns got mangled in your question. I don't think that it is showing any computers connected, rather just that you have process(es) listening on those ports.

To find out what Windows process is involved, you can do a netstat -anb (you may have to do this with Administrator priviledges).

Port 1900 is used for the ssdp protocol. You could turn this off by disabling the SSDP Discovery service.

I'm not sure what corresponds to port 50524, but on my system, that same SSDP Discovery service is listening on a number of high numbered ports... it may be the same for you.

You can't close an open socket just like this. Ideally, you would just kill the process that has established the connection.

Check your connections with lsof (netstat won't show the process), filtering the output with whatever connection status you want:

lsof -i
lsof -i | grep LISTEN
lsof -i | grep ESTABLISHED

Or, to get the port, e.g. 17500:

lsof -i:17500

Then, just kill the process. For example:

$ lsof -i | grep "Skype"
Skype     438 werner    9u  IPv4 0xffffff801dd0c640      0t0  UDP localhost:52218
Skype     438 werner   42u  IPv4 0xffffff80231a7a08      0t0  TCP *:29429 (LISTEN)
Skype     438 werner   43u  IPv4 0xffffff8022e18a40      0t0  UDP *:29429

Kill Skype:

killall Skype

Note though that this won't prevent the connections from being made – something you have to specify in your Firewall preferences.