It is possible - only while a job is running - to access the Heritrix user interface on the harvester machine.
Start a browser on the harvestermachine and use the port specified, e.g. http://my.harvester.machine:8090. The port is defined by the setting
Enter the administrator name e.g. "admin" and password e.g. "adminPassword" as set in the
settings.harvester.harvesting.heritrix.adminName and in
See in the installation manual how you change settings.
In the Heritrix GUI you can e.g. pause, stop or restart a job.