CyberGuard dictionary / Network Security
Private IP
A private IP address is an address from a range reserved for use within private networks rather than routing directly on the public Internet.
In simple terms
Different homes and offices can reuse the same private IPv4 ranges because those addresses are not globally unique.
Technical explanation
RFC 1918 reserves 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 for private IPv4 use. To communicate with public destinations, networks commonly translate source addresses or use a gateway.
Private address ranges are used inside networks and are not directly routed across the public internet. Their use does not guarantee that an internal device or service is trusted.
Examples in practice
A printer at 192.168.1.20 works inside an office but cannot be reached from the Internet solely by that address.
A database at a private address is reachable only from the application subnet. When a compromised workstation enters that subnet, firewall rules still prevent direct database access.
Why it matters
Private addressing supports local network design but does not replace segmentation or authentication.
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Sources and further reading
Published 2026-10-15 · Last updated 2026-10-15 · CyberGuard editorial content. Source links provide context; they do not imply endorsement.