A storage administrator is troubleshooting lack of connectivity between an iSCSI-initator and iSCSI-target that is located behind a firewall. The firewall has the following active rule base: Allow udp

iSCSI's core data plane relies on TCP/3260, not the RPC protocol, so its functionality behind a firewall is primarily dependent on allowing the correct TCP port.

iSCSI utilizes TCP port 3260 for its primary communication between the initiator and target. The firewall rule set explicitly allows UDP port 3260 but blocks the necessary TCP/3260 connection, which is the most likely cause for the lack of connectivity.

iSCSI (Internet Small Computer System Interface) is a protocol that encapsulates SCSI commands over standard TCP/IP networks, making it fundamentally a TCP/IP-based protocol.

While NAT can introduce complexities, the immediate issue with the given firewall rules is the explicit blocking of the standard iSCSI TCP port, not an inherent incompatibility with NAT requirements.