Connecting programmable logic controllers (PLCs), human machine interfaces (HMIs), and other automation system components to the Industrial Internet of Things (IIoT) for remote access is important for many manufacturing plants, and to the machine builders providing equipment and services to these plants. In the past, remote access was often accomplished via a router without a virtual private network (VPN), but these router-only connections to the internet should not be implemented today due to security risks.
Instead, a VPN should be used, as it is one of the key elements to a defense-in-depth strategy. However, implementing a secure IIoT connection to automation system components via a VPN often presents cost, technical, and resource allocation issues. The two solutions presented in this article address these challenges, but in different ways. Each solution has its own advantages and design considerations. The two options are hosted VPN and traditional VPN.