I have win10 Pro on a offline computer. I have a Synology NAS. So, I have the internet cable plugged in and have everything except for port 5000 (the NAS) disabled. Therefor no internet, no programs online, no services etc. Now I have another program that need to access the internet. Is there a easy way to just allow that one program and the NAS? Like with a firewall or something? Everything I see is ALL programs and everything. Or you have to do all of them individually. Which is 1000s or so.
By default Windows's firewall allows outgoing connections, but you can override this to mode when every outgoing connection will be blocked by default unless you explicitly allow it.
Control Panel\All Control Panel Items\Windows Firewall
then switch to
Advanced settings and do these 3 steps shown on screenshots.
On the second screenshot you should change outgoing rule for all profiles:
Domain, Private and Public