I wrote a tool that does what you want (an inetd service that you put
in place of any UDP or TCP based service that logs the attempt but
does not accept the connection). It's called klaxon and is available
at either ftp.eng.auburn.edu:pub/doug or http://www.eng.auburn.edu/users/
doug/second.html.
There's another tool on the www page that I use to watch the logs and
inform me when critical security or other system events occur. It's
called tklogger.
Doug Hughes Engineering Network Services
doug@eng.auburn.edu Auburn University