Finger protocol





The finger protocol is a simple network protocol based on RFC1196 (The
Finger User Information Protocol). Typically the server side of the protocol
is implemented by a program "fingerd" (for finger daemon), while the client
side is implemented by the "name" and "finger" programs. The program is
supposed to return a friendly, human-oriented status report on either the
system at the moment or a particular person in depth. There is no required
format, and the protocol consists mostly of specifying a single command
line. It is most often implemented on Unix or Unix-like systems.

The program would supply information such as whether a user is currently
logged-on, e-mail address, full name etc. As well as standard user
information, finger displays the contents of ".plan" file in the user's home
directory. Often this file (maintained by the user) contained either useful
information about the user's current activities, or alternatively all manner
of humor.

Supplying such detailed information was considered acceptable and convenient
in the early days of the Internet, but later was considered questionable for
privacy and security reasons. Finger information has been frequently used by
crackers as a way to initiate a social engineering attack on a company's
computer security system. By using a finger client to get a list of a
company's employee names, email addresses, phone numbers, and so on, a
cracker can telephone or email someone at a company requesting information
while posing as another employee. Information garnered from finger can be
used both to find an employee to contact directly, and to more effectively
pose as an existing employee. The finger daemon has also had several
exploitable security holes which crackers have used to break into systems.

For these reasons, while finger was widely used during the early days of
Internet, by the 1990s the vast majority of sites on the internet no longer
offered the service. Notable exceptions include John Carmack, who still
updates his status information occasionally.