What is an Air Gap?
An air gap is a physical or logical separation between two networks, with no direct connection between them (such as cables, Wifi or Bluetooth). The aim is to keep a system fully isolated from other networks, particularly the internet or corporate IT.
An air-gapped system is therefore unreachable over normal networks and provides a high level of protection against external attacks or Malware infections.
🧠 Why use an air gap?
Air gaps are used in situations where maximum security and reliability are required. They prevent sensitive systems from being affected by:
- Viruses, ransomware or spyware
- Unauthorised external access
- Unintended data exchange
🏭 Applications of air gaps
| Application | Explanation |
|---|---|
| Nuclear facilities | No connection to the internet or external networks |
| Industrial control systems (ICS) | PLC, SCADA, RTU or DCS systems kept fully separate |
| Government / defence | Protection of classified or state-sensitive information |
| Backup servers | Prevent ransomware from also encrypting backups |
🔧 Examples of an air gap
- An industrial computer that is never connected to a network
- Data exchange only via USB stick or CD/DVD, with manual approval
- Use of data diodes to permit one-way traffic only
❗ Drawbacks of an air gap
While highly secure, an air gap also has drawbacks:
- More difficult updates and management (manual transfer of patches/software)
- Complexity in log collection and monitoring
- Risk of human error during physical data transfers (“sneakernet”)
📌 In summary
An air gap is a powerful network isolation measure that ensures a system is fully decoupled from other networks. It is mostly used in critical infrastructure where availability and security are critical.