Files that contain the .cnf file extension are most commonly associated with telnet connection files. These CNF files store the information that the computer uses in order to make a telnet connection.
Files with the .cnf extension may contain the name of the telnet server that is being used as well as the username and the password of the telnet user. The CNF file that is used by the server software works like a shortcut, allowing users quick access to commonly-used telnet sessions.
Lotus 1-2-3 has also been known to use the .cnf file suffix. These CNF files contain the configuration files that are referenced during the use of the Lotus 1-2-3 application.
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