CHARGEN is a portmanteau term that stands for "Character Generator." It refers to a networking service or protocol designed for testing, diagnosing, or troubleshooting issues related to network connectivity and equipment performance. Initially developed for Unix-like operating systems, CHARGEN functions by generating a continuous stream of characters or data that is sent to a remote system.
The CHARGEN protocol predominantly operates on User Datagram Protocol (UDP) port 19. The fundamental purpose of CHARGEN is to verify and evaluate network performance by measuring packet loss, round-trip time, and throughput capacity. It accomplishes this by generating repetitive data, which can be used to identify problems with network equipment, connections, or software configurations.
CHARGEN is typically implemented as a server-client model, with the sender (server) continuously transmitting random or pre-defined characters, and the receiver (client) analyzing and assessing the received data. Specific implementations can vary, with some providing options for specifying the type and length of data to be transmitted.
Despite its original purpose for network diagnostics, CHARGEN has been largely deprecated and its usage discouraged due to security concerns. The open nature of CHARGEN makes it vulnerable to exploitation by miscreants, as it can be exploited for distributed denial-of-service (DDoS) attacks, leading to network congestion or service unavailability.
In summary, CHARGEN is a network service or protocol that generates character-based data to test and diagnose network connectivity problems, though its usage has diminished due to security vulnerabilities.
