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Many telnet clients also include a third option, the port on which the connection should take place. Normally, port 23 is the default telnet port; the user never has to think about it. But sometimes it's desirable to telnet to a different port on a system, where there may be a service available, or to aid in debugging a problem. Using
telnet somewhere.domain port
will connect the user to the given port on the system somewhere.domain. Many libraries use this port method to offer their facilities to the general Internet community; other services are also available. For instance, one would type
telnet martini.eecs.umich.edu 3000
to connect to the geographic server at the University of Michigan (see section Geographic Name Server). Other such port connections follow the same usage.
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