Windows works (nearly) fine if you block all connections except those from the "Core Networking" group. Of course you won't have access to some services in tha

Windows works (nearly) fine if you block all connections except those from the "Core Networking" group. Of course you won't have access to some services in that case, like Windows Update, etc. One particular weird thing I have noticed is that the process that checks CRL on behalf on others is LSASS. So basically you have some extra tuning to do to get a system to your liking if using just the Windows Firewall, after you block everything but "Core Networking" (and programs you want to authorise), but it looks reasonable. I would suggest saving the initial state before you go that route, though. If you trace connections you will find funny things, like cl.exe phoning home.