Wietse Venema's network logger, also known as TCPD or LOG_TCP.
These programs log the client host name of incoming telnet, ftp, rsh, rlogin, finger etc. requests.
Security options are:
- access control per host, domain and/or service;
- detection of host name spoofing or host address spoofing;
- booby traps to implement an early-warning system.