Initialize the telnet connection

def _init(self):
        """Initialize the telnet connection
        """
        self.tn = telnetlib.Telnet(self.ip, self.port)
        self.tn.read_until('User Name')
        self.tn.write('apc\r\n')
        self.tn.read_until('Password')
        self.tn.write('apc\r\n')
        self.until_done()