Software Defined Networking (SDN) is established as a widely used concept in networks and has been introduced into the network architecture of Industrial Internet of Things (IIoT). Adversaries targeting on disrupting the operation of an IIoT system can launch a simple yet effective attack - malicious packet-modification attack (MPA) - that was previously identified in IoT based on wireless sensor networks. To mitigate MPAs, we introduce an approach for secure and reliable data transmission in the presence of such active attackers by utilizing the programmability and flexibility offered by SDN. Our approach ensures that modifications are recognized by IIoT devices. The effectiveness and performance of the proposed solution was evaluated in comprehensive tests by means of a prototypical implementation. The results confirm that malicious forwarding devices can be reliably and quickly identified and, hence, bypassed even if they modify only a portion of the data.