S-terminal lets you create a secure X terminal over an ecrypted tunnel.
Regular X terminals pass unencrypted data between you the remote machine.
S-terminal creates an encrypted tunnel through which all X traffic passes.
It replaces the remote xdm login screen with a local application that collects username and password, then sets up an ssh tunnel to the remote host and starts a session.
It is highly configurable both in appearance and behavior, and deployed S-terminals can be remotely administered.
S-terminal was developed to run under Knoppix, but it should be portable to most Linux systems. With minor changes, it should work on any Unix-like system that has X, perl, tcl/tk and expect installed.
Best of all, it can be added to a KNOPPIX CD to create an instant, bootable, secure X terminal CD.