A CHARGEN amplification attack is a Layer 4 reflection and amplification vector, one of the volumetric classes a thorough DDoS test is built to exercise. CHARGEN (Character Generator Protocol) is a legacy diagnostic service on UDP 19 that replies to any packet with a stream of arbitrary characters. The attacker spoofs the victim's IP in a tiny request to exposed CHARGEN hosts, and each one floods the victim with a far larger response. The service has no modern use, yet it remains enabled on enough legacy devices to be abused as a reflector.
Why it matters in DDoS testing
CHARGEN reflection is a reminder that decades-old defaults still surface as live attack surface. Testing confirms whether any host inside the perimeter still answers on UDP 19, whether ingress filtering blocks the spoofed sources, and where the saturated link first drops legitimate traffic. The reflection mechanics common to these vectors are detailed in Understanding DDoS Attack Vectors.