First login to Signals Data Factory's web interface.
Use the following URLs substituting <sdf-host> to obtain:
SDF version
http://<sdf-host>/job-service/version
Also available from Signals (menu top right) > About
Signals Inventa/Lead Discovery client service:
http://<sdf-host>/sld/nginx-client-version
Signals Inventa/Lead Discovery metastore backend service:
http://<sdf-host>/sld/metastore-version