Cybersecurity
Firewalls
Rules, placement, and review.
Written guides in this section
Full references, procedures, and diagnostic guides published under Firewalls.
Industrial Firewalls
Firewalls built for control networks: how they differ from office firewalls, where they belong in a utility network, transparent versus routed modes, Modbus and DNP3 awareness, logging, and the ruggedized units that protect one controller or a remote site.
9 min readUpdated Sep 5, 2026
Firewall Rule Design
Writing the rule set for a control network boundary: default deny, one rule per conduit with its reason, hosts not subnets, protocol and port and function, direction and initiator, logging on every rule, and the review that removes forgotten rules.
9 min readUpdated Sep 5, 2026
Deep Packet Inspection
What a firewall can do when it understands the control protocols: allowing reads and blocking writes, permitting programming only from one workstation in a window, rejecting malformed messages, and alerting on function codes that should never appear.
8 min readUpdated Sep 5, 2026
Firewall Logging and Review
Making the firewall log useful: logging on every rule including sensitive permits, sending logs to a collector off the firewall, what denials and unexpected permits mean, a weekly review a small utility can sustain, and the alerts worth waking someone for.
8 min readUpdated Sep 5, 2026
Topics in this area
Industrial Firewalls
Industrial Firewalls — practical reference notes for controls engineers, integrators, and technicians working with firewalls.
Firewall Rule Design
Firewall Rule Design — practical reference notes for controls engineers, integrators, and technicians working with firewalls.
Deep Packet Inspection
Deep Packet Inspection — practical reference notes for controls engineers, integrators, and technicians working with firewalls.
Logging And Review
Logging And Review — practical reference notes for controls engineers, integrators, and technicians working with firewalls.
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