We advise to authenticate users by public keys to execute command on DPI server remotely by SSH with no need to enter password.

To use this method: on the control server:

We create a pair of public and private keys:

ssh-keygen -t rsa

We select default values in a dialogue. We keep the secret phrase empty to simplify further usage1) Alternatively, one can use the functionality of ssh-agent to store passwords.

Next, we copy the public key to DPI server:

ssh-copy-id dpi_user@dpi_host
or manually:
cat ~/.ssh/id_rsa.pub | ssh dpi_user@dpi_host "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"

Then we check and fix the rights on file authorized_keys on DPI server:

chmod 700 ~dpi_user/.ssh/
chmod 600 ~dpi_user/.ssh/authorized_keys
restorecon -Rv ~dpi_user/.ssh/

Next, we check the operation of the remote execution of fdpi_ctrl from the control server:

ssh dpi_user@dpi_host "fdpi_ctrl load --service 6 --login test"

In case this instruction does not work, try to find some hints in the log file /var/log/secure on DPI server. One can also switch the diagnostic mode on SSH: ssh -v …