I'm currently writing a program which transfers files over a network.
The one person sharing the files run a server and the one who wants
to get connect using a application. Now the client also connects via
Telnet to say what he wants and to see what is available. The server
automaticly uses the telnet input to send the file to the
application. Now i have the following problems:

The user has to enter a password. Now how do i get it that telnet
does not echo the input the user gives?

I know how to list files using the File class but how do i change the
current directory. If its to another sub directory (cd uploadz) or to
the base directory (cd..)?

Further i think a have everything under control