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Knowledge base

Understand the threat. Then meet it.

Electromagnetic eavesdropping and attacks on critical infrastructure are not science fiction – they are today's baseline threat level. These guides explain the risks and the certified hardware that answers them, for the public and private sector alike.

Start with TEMPEST/RÖSWhat is a data diode?
Guides
16
Glossary
84
Environments
49
Architecture patterns
26
  1. TEMPEST and RÖS explainedAll electronics leak electromagnetic signals that can be intercepted at a distance. TEMPEST (RÖS in Sweden) certification levels A, B and C define how well equipment is protected.
  2. Today's threat levelAttacks on power grids, hospitals and public authorities are daily operations, often state-sponsored. Why software defences are necessary but insufficient – and what to protect physically.
  3. What is EMSEC?EMSEC is the discipline of protecting against information leakage through unintentional emanations. How it relates to TEMPEST, RÖS and COMSEC – and why encryption does not help.
  4. What is a data diode?A data diode is hardware that physically enforces one-way data transfer between networks. How it works, why it beats a firewall for critical systems, and where it is used.
  5. One-way protocols: UDP, Syslog, NTP and SNMP over a data diodeTCP cannot complete across a data diode. Which protocols cross natively, how middleware handles the rest, and how to plan the flows before the hardware arrives.
  6. Data diode vs firewallA firewall decides what may pass; a data diode makes the return path impossible. Where each belongs, why critical environments use both, and what a diode costs you in practice.
  7. Bidirectional data diodes – when a controlled return channel is neededSome flows are conversations. A bidirectional pair gives two independent hardware-enforced one-way channels – without softening the diode into a firewall.
  8. SDIP-27 and TEMPEST levels A, B and CSDIP-27 is the NATO standard that defines TEMPEST protection levels A, B and C, and how they map to the Swedish RÖS levels U1, U2 and U3. How to choose the right level for an environment.
  9. M-numbers and FMV – what they mean for a buyerAn M-number identifies an approved article in the Swedish Armed Forces materiel system. What it guarantees, how it differs from a TEMPEST certificate, and why it matters in procurement.
  10. MIL-STD 461 – electromagnetic compatibility for defence equipmentMIL-STD 461 decides whether equipment can share a vehicle, a mast site or a command post with radios and radars. The four requirement families, and how EMC differs from EMSEC.
  11. IEEE C37.94 explainedIEEE C37.94 is the optical interface between protective relays and communication equipment in power grids. Why fiber replaced copper, and how it bridges into E1, SDH and SyncE.
  12. G.703, G.704 and E1 – the telecom interfaces that refuse to dieNew networks are Ethernet, but critical infrastructure still speaks E1. What the three standards actually cover, why they persist, and how to carry them securely over fiber.
  13. Singlemode vs multimode – which fiber do you need?Multimode fiber is cheaper over short distances; singlemode carries further. How core diameter, wavelength and reach decide which one belongs in a secure installation.
  14. Why galvanic isolation mattersGalvanic isolation means no conductive path between two systems. Fiber gives it for free – and it solves ground loops, surges, interference and eavesdropping in one property.
  15. MIL-STD 810G – what 'rugged' actually meansAnyone can print rugged on a datasheet. MIL-STD 810G turns the word into a verifiable claim – and three questions separate real ruggedisation from a thick chassis.
  16. Fiber optic teleprotection and trip linksA trip command must arrive in milliseconds, unfalsified, during the fault it exists to clear. Why copper pilot wires fail exactly then, and how to choose an optical trip link.

Knowledge base

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