[transpute]

> is this widely used

Single Packet Authorization (SPA) is an architectural pattern of modern cloud security ("Software-Defined Perimeter"), with multiple OSS and proprietary implementations, https://cloudsecurityalliance.org/artifacts/software-defined...

  UDP-based SPA provides the following security benefits to the SPA-protected server:

  ● Blackens the server: The server will not respond to any attempted connections from any remote system until they have provided an authentic SPA that is valid for that SDP system. Specifically, the host will not respond to a TCP SYN, thereby avoiding the disclosure of any information to a potential attacker.

  ● Mitigates Denial of Service attacks on TLS: Internet-facing servers running the HTTPS protocol are highly susceptible to Denial-of-Service (DoS) attacks. SPA mitigates these attacks because it allows the server to reject unauthorized connection attempts before incurring the overhead of establishing a TCP or TLS connection and therefore allowing authorized connections during and in spite of DoS attacks.

  ● Attack detection: The first packet to an AH from any other host must be a SPA packet. If an AH receives any other packet, it should be viewed as an attack. Therefore, the SPA enables the SDP to determine an attack based on a single malicious packet.