Frequently Asked Questions

This is the first release of the CPTAC Data Exchange Sandbox for the CPTAC community.

The Functions included are:
  • Secure Login
  • User Password Management, Registration and Recovery
  • Upload and Download of Data from PCC Private and CPTAC Shared Directories
  • Encryption of Data during transport
  • Data integrity verification for each transmitted block
  • Deletion of Data by the Data Owner

  • 1. Why can’t I upload or download files?

    If you are inside of a university or institution VPN (Virtual Private Network) the transfer of data to the CPTAC Data Exchange Sandbox may be prevented by your VPN. To keep data secure this website uses non-standard ports for communication between your computer and the Data Coordinating Center (ports are virtual connection points between two computer systems).

    What should you do?
    • First try to connect to the CPTAC Data Exchange Sandbox from outside the VPN (for example from your home computer). If you can connect and transfer files then you know that the issue is with the VPN that protects your standard work station.
    • If you can not connect when you are outside of your VPN, contact the DCC at
    • If you can connect from outside of your VPN but not from your standard workstation, you will need to request your IT support group to open communication ports in your VPN to let you connect from work to the CPTAC Data Exchange Sandbox. The information you need is:

      The CPTAC Data Exchange Sandbox with the Aspera Connect Server uses non standard ports for security, UDP 33001 for file transfer and TCP 33001 for User Authentication (via SSH).

      Your IT Support Group will need to set a firewall rule that enables opening a UDP/TCP connection on port 33001 to the server IP (

      The purpose of using TPC 33001 for User Authentication is to deter hackers. From the Aspera security guidelines, “It is well known that SSH servers listen for incoming connections on TCP Port 22. As such, Port 22 is subject to countless, unauthorized login attempts by hackers who are attempting to access unsecured servers. A highly effective deterrent is to simply turn off Port 22 and run the service on a seemingly random port above 1024 (and up to 65535). To standardize the port for use in Aspera transfers, we recommend using TCP/33001”

      The DCC has written a document that summarizes the CPTAC Data Center and Data Portal Organization and Security for your reference. You can obtain this document from the NCI CPTAC Intranet in the DCC Project Team folder or e-mail
  • 2. Where can I get documentation for the Aspera connect client that I installed on my computer?

    Go to the Aspera web site
    Under the tab for “products” select “client software”
    From the list of client software, select aspera connect
    Select the download tab and choose your operating system
    From the pull down menu select the version
    A user guide and release notes can be downloaded from this page

  • 3. How can I request new features for the CPTAC Data Exchange Sandbox?

    Feature requests, suggestions, and comments are always welcome and can be sent to: