How can I secure communications between client and server using terminal server?

Low

This level secures the user logon information and data sent to the server, but not the data sent from the server to the client. Microsoft recommends that you use this encryption level when the network is secure (e.g., an intranet).

Medium

This level encrypts the data transmission in both directions. Microsoft recommends that you use this encryption level when the network isn't secure and resides outside of North America (because of 128-bit export restrictions). NOTE: If you connect to a Win2K server running Terminal Services set for Low or Medium encryption levels and use version 4.0 of the Terminal Services client, your data is encrypted using a 40-bit key. If you are using version 5.0 of the Terminal Services client, your data is encrypted with a 56 bit-key.

High

This level encrypts the data transmission in both directions using a 128-bit key. Microsoft recommends that you use this encryption level when the network isn't secure and resides within North America.