portmaster

Portmaster is a free, open-source privacy firewall from Safing that gives Windows users granular control over network connections. It visualizes every outbound connection, allows per-app firewall rules, encrypts DNS by default, and applies system-wide tracker and malware blocklists. Portmaster is often included in open-source security baselines alongside tools like VeraCrypt and BleachBit to enhance privacy and reduce attack surface. However, it requires careful configuration and awareness of known DNS and VPN compatibility quirks before being trusted on a production workstation. The tool is designed for power users who want tight outbound controls and transparent network monitoring.