#Physical Network Security
#Air-Gapped Networks
True air gap: no WiFi, no Bluetooth, no USB (unless sanitized), no internet.
Design:
- Physical barriers: locked server rooms/cabinets
- Data diodes for one-way data flow (Owl Cyber Defense, Waterfall Security)
- Offline patch management with dedicated update stations
- Supply chain verification for all hardware
- Disable all wireless radios, USB ports, audio jacks (acoustic covert channels exist)
Guide: https://cybersguards.com/air-gapped-networks/
#TEMPEST Shielding (NSA Emanation Security)
Prevents electromagnetic emissions from being intercepted.
Levels:
- Level A (NATO SDIP-27 Level A): full protection, shielded rooms
- Level B: reduced protection for less sensitive environments
- Level C: minimum protection
Implementation: Faraday cages, shielded cables, filtered power lines. SCIFs per ICD 705.
For home lab (practical alternatives):
- Shielded Ethernet cables (STP/FTP)
- Keep sensitive equipment away from windows
- Small Faraday enclosure for specific devices
Caveat: Ben Gurion University research shows low-frequency magnetic fields from CPUs penetrate metal shields. Faraday alone does not guarantee air-gap integrity.
References: