Welcome

PortGuard is a fwknop-compatible Single Packet Authorization (SPA) solution for protecting private services from unauthorized access and malicious port scanning.

PortGuard Client is a cross-platform client that supports the fwknop SPA protocol. It can send compatible authorization packets to fwknopd or PortGuard Server from Windows, macOS, iOS, and Android.

PortGuard Server is based on the upstream fwknop project with PortGuard-specific modifications. It keeps service ports closed by default and opens them temporarily only after a valid SPA packet is verified.

This model reduces the exposed attack surface for SSH, VPN, NAS, and administration panels. The underlying fwknop-compatible protocol provides encryption, HMAC authentication, and timestamp validation to prevent replay and tampering.

Thanks and enjoy PortGuard!