Private IP addresses

by | Jul 23, 2026 | Security | 0 comments

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Everybody knows the private IP addresses, no ? do you actually know them all ?

RFC1918 defines the most used ones

10.0. 0.0 – 10.255. 255.255 (10/8 prefix)
172.16. 0.0 – 172.31. 255.255 (172.16/12 prefix)
192.168. 0.0 – 192.168. 255.255 (192.168/16 prefix)

Then there is : 169.254.0.0/16 used when DHCP isn’t working

RFC 4193 defines the IPV6 ones : https://datatracker.ietf.org/doc/html/rfc4193

fd00::/8

or fe80::/10 for autoconfiguration

Loopback addresses IPV4 : 127.0.0.0/8

Carrier-grade NAT ranges

100.64.0.0 – 100.127.255.255 : 100.64.0.0/10

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