Currently, the TFTP server used in Device Config Backup to retrieve configuration files from devices has its port number set to 6969 or similar (tftp 'blueprint.xml' configuration).
The SSH script files executed on the client device assume the default TFTP port (69). Since OpenNMS runs under non-elevated privileges, the OpenNMS server machine needs to configure port forwarding to forward from 69 (assumed by client) to 6969.
The port number in the scripts could be parameterized to include a port number, so the TFTP client directly connects to 6969 without the need for port forwarding. 'tftpServerIp' is already parameterized in SshScriptingServiceImpl, can add 'tftpServerPort' as well, then add this parameter to scripts as needed.