Secure Data Bridging in Industry 4.0: An OPC UA Aggregation Approach for Including Insecure Legacy Systems
This work addresses the challenge of securely enabling data interoperability between isolated legacy systems and modern secure zones in Industrial 4.0 environments. The authors propose SigmaServer, a TCP-layer OPC UA aggregation mechanism that bridges legacy systems lacking native OPC UA support with contemporary architectures within an operational technology (OT) testbed. By doing so, SigmaServer overcomes the data flow limitations imposed by traditional air-gapped isolation strategies while preserving stringent security boundaries. Experimental validation demonstrates that SigmaServer effectively balances security and compatibility, facilitating efficient and reliable cross-domain data exchange. This approach offers a practical solution for heterogeneous integration in industrial control systems, where legacy infrastructure must coexist with evolving security and communication standards.