telnet session

[eight02645999 at yahoo.com]

hi
i am using a telnet session to simulate an authentication mechanism
USER = "user"
PASSWORD = "password"
try:
        telnet = telnetlib.Telnet(HOST)
        telnet.set_debuglevel(5)
        telnet.read_until("login: ")
        telnet.write(USER + "\n")
        telnet.read_until("Password: ")
        telnet.write(PASSWORD + "\n")
except:
        print "failed to telnet"
else:
        try:
                telnet.write("ls\n")
        except:
                print "cannot ls"
        else:
                telnet.write("exit\n")
                print telnet.read_all()


When i purposely input a wrong password, it "hangs" at the login prompt
waiting for
login and Password. The host i am telnetting to is a unix server.
How can i "exit" this login prompt if the user keys in wrong password
in my script?

thanks