Telnetlogger is a lightweight program designed to log login attempts on Telnet port 23, specifically created to track activity from the Mirai botnet. The tool captures both IP addresses attempting connections and the passwords being used in brute force attacks. It was developed as an alternative to traditional telnetd installations, which the Mirai botnet reportedly does not interact with properly. Key features include: - Real-time logging of Telnet login attempts to stdout - Optional file output for passwords and IP addresses using -p and -i flags - Configurable port listening with -l option for testing purposes - Built-in parsing capabilities to extract usernames and passwords from connection attempts The program requires elevated privileges (sudo) on many systems when binding to ports below 1024. It provides a simple compilation process using make and is particularly useful for security researchers studying botnet behavior and attack patterns targeting IoT devices.