Diagnosing CGNAT and Public IPv4

What is CGNAT?

Carrier-Grade Network Address Translation (CGNAT) is a technique used by Internet Service Providers (ISPs) to deal with the shortage of available IPv4 addresses. In a CGNAT environment, multiple customers share a single public IPv4 address, hindering the ability to directly forward ports to devices within a network.

Diagnosing CGNAT

Check Your Router's WAN IP:

• Log in to your router and locate the WAN IP address. If it's a private IP address (e.g., 10.x.x.x, 100.x.x.x, 192.168.x.x,), your network is likely behind a CGNAT.

• Check if your routers WAN IP matches the IP address on browserleaks.com/ip, if the IP's does not match then you can be certain CGNat is enabled for your Internet service.

Check with Your ISP:

• Contact your Internet Service Provider and inquire about your IP address type. If they confirm it's a private IP, you're likely under CGNAT.

Dealing with CGNAT

Contacting Your ISP Requesting a Dynamic Public IP:

• Inform your ISP about the port forwarding needs.

• Request a dynamic public IP address to enable you to forward ports.

• Some ISP's charge extra for a static IP if the ISP can't help you with a dynamic IP.