IBM Support

ascp connectivity testing

Question & Answer


ascp connectivity testing




Aspera transfers are able to function thanks to ascp which runs on both a server and client when a FASP transfer is being made. ascp can also be used as a command line tool to make transfers directly with commands rather than a GUI.

The ascp command line tool can additionally provide a quick and simple method of checking whether a client can properly connect to a server to make an Aspera transfer at all.

The method involves using an ascp option that tests and measures the bandwidth between the client and server.


The general syntax for testing ascp connectivity is the following:

[ASPERA_SCP_PASS=remote_password] ascp -wf -P ssh_port remote_user@remote_host:/

Replace the placeholders in the command as follows:

  • remote_host: The IP address or host name of the Aspera server
  • remote_user: A valid transfer user on the Aspera server
  • ssh_port: The port on the Aspera server used for SSH authentication
  • remote_password: The transfer users password (optional)

The -wf option specifies that bandwidth should be measured from the client to the server.

Note: You can choose not to include the ASPERA_SCP_PASS value and type in your password after running the ascp command instead.


If a connection can be successfully established between client and server you will see a response like the following after running the command:

Measuring bottleneck bandwidth from to
Measured bottleneck capacity: 426.3 Mbps

If a connection cannot be successfully made you will see an error message.

For instance if your SSH (TCP) port is being blocked by a firewall you would see the following:

ascp: Failed to open TCP connection for SSH exiting.

Session Stop (Error: Failed to open TCP connection for SSH)

For more information on this TCP connection error see this KB article on the TCP error 44.


If you want to test ascp connectivity to a server at where the transfer user is jane_doe the password is aspera and the SSH port is 33001 you would use the following command:

ASPERA_SCP_PASS=aspera ascp -wf -P 33001 [email protected]:/ 

You can run this same command without the password value and type in the password when prompted after running the ascp command:

# ascp -wf -P 33001 [email protected]:/

[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSL85S","label":"IBM Aspera High-Speed Transfer Server (HSTS)"},"Component":"","Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"All Versions","Edition":"","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
08 December 2018