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Self-Hosting Portmaster: Application Firewall

Portmaster is an application firewall that monitors and controls network connections. See what your apps connect to and block what you don't want.

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What Is Portmaster?


Portmaster is a free, open-source application firewall. It monitors network connections per application and lets you control what connects where.


Features


Monitoring

  • Per-application network connections
  • DNS query logging
  • Connection history
  • Bandwidth per application

    • Blocking

  • Block connections per application
  • Block domains globally
  • Filter lists (ads, trackers, malware)
  • Country-based blocking

    • DNS

  • Encrypted DNS (DoH, DoT)
  • DNS-based content filtering
  • Multiple DNS providers
  • Custom DNS rules

    • Privacy

  • SPN (Safing Privacy Network) — optional VPN-like protection
  • Tracker blocking
  • Telemetry blocking

    • Portmaster vs Little Snitch vs GlassWire


  • Portmaster: Open-source, Linux/Windows, free
  • Little Snitch: macOS only, polished, paid
  • GlassWire: Windows-focused, monitoring-heavy, freemium

    • Use Cases


  • See what applications phone home
  • Block telemetry from desktop apps
  • Block ads system-wide
  • Control which apps can access the internet

    • Deployment


    Install directly on your desktop/laptop (not a server tool). Free for personal use.


    Portmaster reveals what your applications are doing on the network. The visibility alone is eye-opening.