The command "man telnet" will help you. It describes just about everything you can do with telnet on a linux system. Simply,
jim@jimsworktop:~/test$ telnet (name or IP) (optional port number)
So telnet gmail.com 25 will telnet you to gmail at port 25, and
telnet 192.168.1.1 will telnet to 192.168.1.1 at the default port, 23.
Peace,
JimBass
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