Originally Posted by Teal
PLC’s are hard to hack as they are not casually connected to WAN’s. The supervisory system on ships are not connected to WAN’s, just local networks, not the internet.

These days the LAN most PLCs are connected to is just VLAN'd off from the WAN. Either that or the PLC network contains a remote device that VPNs up to the internet. This is done for remote support purposes, diagnostics, centralized maintenance, etc.