deny a user from telnet in linux

1) denying telnet for all can be done. But i need to restrict telnet for one particular user. How can i?

2) After telnet by the particular user, i want to disable the user viewing the other files and directories. i want to give privilege to the directory, he is logging in. Other than applying chmod to all the directories, is there any solution?

Thanks,
p.sampath kumaran