10 Jeff Keene Christian Grothoff 2010 München The DUP Project 06/2010 dup protocol This document specifies the second version of the DUP protocol. It specifies the information sent from DUP to the DUPDs as well as the format of the messages between multiple DUPDs. The main changes in this version are the use of {\tt ssh} to support authentication of users and to secure the communication of the session information.