Firewall
In computing, a firewall is a network security system that monitors and controls incoming and outgoing network traffic based on configurable security rules.[1][2] A firewall typically establishes a barrier between a trusted network and an untrusted network, such as the Internet,[3] or between several VLANs.
Simplewall
Free opensource firewall for WIndows
GitHub
Portmaster
Free limited, Opensource
Safing
Plus license $48/year
Glasswire
Free limited
Glasswire
1 license discount: SECURESTART15 $31/year UFD15 BIZ30 DUO30