Wietse Venema's TCP wrappers library

 Wietse Venema's network logger, also known as TCPD or LOG_TCP.
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 These programs log the client host name of incoming telnet,
 ftp, rsh, rlogin, finger etc. requests.
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 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.