remote access again with telnet

How can somebody connect to a computer with telnet, if he knows it is running xp and he knows password? It is possible? Some computers(For example in internet café) have IP, that is not scanable, I think, if somebody scans ports on them, he becomes no answer. Why? And how can he find there the IP adress, that he can join with telnet? And if it isnt enough, what another must he has?
And something, what not belongs here: I can write a mail by telnet, but can somebody tell me the orders to read the mail trough pop3? I can only login in my post but I cant read the mail, because I dont know how.

Try here:

http://www.blogontheweb.com/nimrod/a...12/28/423.aspx

http://www.walthowe.com/navnet/faq/telnet.html

http://www.uwo.ca/its/doc/hdi/infose...31-telnet.html



cheers,