OpenSPA: An open and extensible Single Packet Authorization (SPA) implementation of the OpenSPA Protocol.
This software is under heavy development (2021). No guarantees are made that it will remain backwards compatible in it's current form. We WILL break it during development. You have been warned. Don't worry, we are always happy to get contributors. If you are interesting do get in touch: hello[at]openspa[dot]org.
OpenSPA is an open and extensible SPA implementation built upon the OpenSPA Protocol. OpenSPA allows the deployment of a service on an internal network or the internet, that is hidden to all unauthorized users. Authorized users authenticate by sending a single packet to the OpenSPA server, which will reveal itself only if the user is authorized to access the service.
OpenSPA builds what essentially is a dynamic firewall.
Unauthorized users will not be able to detect via the network the presence of the hidden service (no ping, traceroute, port scans, fingerprinting, etc.). Once the user sends an OpenSPA request packet (via UDP) and they are authorized only then will the server respond with a response. Unauthorized users thus will also be unable to confirm the existence of the OpenSPA service.