As a brief introduction, in MPSCP raw data is moved over unsecured socket connections as with most ftp programs. End-user identification, authentication, and authorization, as well as control information (e.g., file names, the number of socket connections needed to move a particular file), are transmitted and encrypted by the underlying ssh connection.
The default tcp/ip port range used by MPSCP is 9000-9999. Due to security restrictions various ports within this range must remain blocked. These ports vary between participating sites. To avoid deadlock situations caused by a port being open at one site but blocked at another, a file containing a comprehensive list of all blocked ports at all participating sites in the 9000 to 9999 range is provided with the MPSCP software. The file is used by MPSCP to avoid assigning blocked ports for file transfer operations.
The latest BC-approved MPSCP file transfer code configuration and blocked-ports files are now part of the openssh kit and can be obtained from HPC Centers: Kerberos & Authentication http://centers.hpc.mil/users/index.html#kerberos. From this page, select your platform and then "Download and Install."