tcpd

Wietse Venema's TCP wrapper utilities
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.