Portmaster is a host-based network firewall and privacy tool that monitors and controls all system network traffic. It operates by intercepting data packets at the operating system level, allowing it to observe and manage every connection made by local software in real time.
The software distinguishes itself through process-aware connection mapping, which correlates active network sockets with specific local applications to provide visibility into data transfers. It utilizes a user-space policy engine to enforce granular security rules, enabling users to restrict internet access, block specific geographic regions, or prevent unauthorized data collection by individual programs.
Beyond basic firewall management, the project provides system-wide DNS filtering and ad blocking by intercepting and resolving domain name queries locally. This approach ensures that tracking and advertising requests are identified and filtered before they leave the host machine, maintaining consistent enforcement of privacy policies across the entire system.
