I have a program that stores data in a folder on its C drive. This is a Windows 7 machine. The folder is shared out. There is also a networked blotter printer that is used just for printing out the files in this share. The printer is shared out on the Windows 7 machine as well. This would be network A.
There are two remote networks, say B and C, that need to connect to this file share. Each network has a Windows-Explorer like program that accesses the file share and opens up these files, which are all proprietary file formats. Inside the network which contains the Windows 7 machine, there's no problem.
I need to set up these networks so that the users on the remote network will be able to access the file share on the Windows 7 machine. I have a decent understanding of routers, so I know I need to open up the WAN port on the network A router and set up forwarding so traffic is directed to the static of the Windows 7 machine. We still have a few public IPs available to us in our ISP-assigned range, so I'm going to dedicate an IP just for this traffic. Plus, I'm going to set up the firewall rules so only the IPs associated with network B and C are allowed to access the IP on the network A router.
What I would like to know is what port to actually open. Since there's a printer involved, the setup would have to allow users on network B and C to print to this printer. They are all near each other (neighbor buildings), so someone might print to this printer and come by to pick it up.