Linux

#!/usr/bin/expect -f
set timeout 3
set HOST [lindex $argv 0]
set PORT [lindex $argv 1]
#$spawn -noecho $env(SHELL)
spawn -noecho "/bin/bash"
send "telnet ${HOST} ${PORT}\r"
expect {
    "Unknown host"
{
 puts "Unknown Host"
exit 1
}

    "Unable to connect" 
    { 
        puts "not connecting" 
        exit 1
    } 
    "Connected to " 
    {
        send -- "\r"
            expect "telnet>"
            send -- "quit\r"
            expect "Connection closed"
            puts "Connecting "
            exit 0
    }
}
send -- ""
exit 1