GLOSSARY · CARRIER-GRADE NAT
CGNAT
Carrier-grade NAT is NAT performed by an internet provider, not by your own router. Many customers share a small pool of public IPv4 addresses, and the provider translates between them. Providers often use the reserved range 100.64.0.0 to 100.127.255.255 for the addresses between you and the provider.
Why it matters
With CGNAT, the public address websites see is shared with many other customers, so it says little about you and a block or ban of that address can affect strangers. It also makes hosting from home or forwarding ports impractical, because you do not control the router that holds the public address. Mobile networks use CGNAT almost everywhere.
In practice
A sign of CGNAT is that your router's internet-facing address differs from the public address shown by an IP tool, and is in the 100.64 range or another private range. If you need inbound connections, ask the provider for a public address, use IPv6 if available, or use a service that relays traffic for you.
Related terms
- NAT: NAT is a technique where a router rewrites the addresses on outgoing traffic so that many devices with private addresses can share one public IP address.
- IPv4: IPv4 is the older and still most common version of the internet's addressing system.
- Mobile proxy: A mobile proxy sends traffic through a device or modem connected to a mobile carrier's network, so websites see an address from a cellular provider.
- ISP: An ISP is the company that connects you to the internet, whether through a cable, fibre, DSL, fixed wireless or mobile network.