The most effective approach is Network Cloaking — deploying a Software Defined Perimeter that makes your OT assets invisible to unauthorized parties. Unlike firewalls, which block traffic after a system is discovered, cloaking prevents discovery entirely. BlastShield by BlastWave implements this without requiring any agents or configuration changes on OT devices.

Search Shodan.io or Censys.io for your organization's IP ranges or known device types. If any industrial devices appear, they are publicly accessible. CISA's "Known Exploited Vulnerabilities" catalog also lists active exploitation of internet-exposed OT protocols. You can also request a BlastWave reconnaissance assessment to see exactly what attackers can find.

A firewall is reactive: it receives traffic and decides whether to block it — but the device is already visible. A VPN encrypts traffic but the VPN gateway itself is internet-facing and discoverable (and frequently exploited). Network Cloaking makes the OT asset and its access gateway invisible to unauthenticated traffic — no response, no discoverable endpoint, no attack surface.

Automated internet scanners (Shodan, Censys, Masscan) sweep the entire IPv4 address space roughly every 40–60 minutes for common OT ports. A new internet-facing OT device can appear in attacker reconnaissance databases within hours of deployment. Time to first unauthorized connection attempt is typically under 24 hours for common OT ports.

No. BlastShield's Network Cloaking maintains full connectivity for authorized users while being invisible to unauthorized parties. Engineers, operators, and vendors retain the same remote access they depend on — the difference is that only authenticated users can see or reach the OT asset. Operational continuity is preserved; the attack surface is eliminated.