slowhttptest binary package in Ubuntu Focal amd64

 SlowHTTPTest is a highly configurable tool that simulates some application
 layer Denial of Service attacks.
 .
 It implements most common low-bandwidth application layer Denial of Service
 attacks, such as
   * Slowloris
   * Slow HTTP POST
   * Slow Read attack (based on TCP persist timer exploit) by draining
     concurrent connections pool
   * Apache Range Header attack by causing very significant memory and CPU
     usage on the server.

Source package