1st of all thanx to all those friends who helped me previously in understanding telnet basics. But one of my friend told me that telnet can be used as a hacking tool when you've a port open in your system and other person know your ip address and open port, he/she can be connect you remotely and do whatever he want, doesn't matter whether you've given him permission or not. Is it true? if yes than how can i save my ass.