Which PORTS?

I operate a small network (5 PCs so far) and I use Comodo Firewall in all. I find that when I connect to the internet an IP I don’t recognize wants to connect to Port 445 → e.g 10.1.15.xxx. Is this Microsoft? SHould I block all access to this port? What other ports should be blocked? Which ports are essential to maintain flawless file sharing and communication across my network without compromising security to the Internet?

See this link on information in relation to Port 445: GRC | Port Authority, for Internet Port 445