Internet-Security.com UDP port 9001 details

UDPcast uses UDP ports 9000 and 9001 by default, with 9001 typically serving as the control/acknowledgment channel during transfers.
Clonezilla/DRBL (for multicast disk imaging) relies on UDPcast and therefore uses UDP 9001 by default when performing multicast or broadcast cloning.
FOG Project’s multicast imaging also uses UDPcast under the hood and thus uses UDP 9001 (alongside 9000) unless reconfigured.
Outside of UDPcast-based imaging tools, there are no widely adopted, standardized protocols commonly tied to UDP/9001.

UDP 9001