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Not much i can specify here - its obvious that my CPE is NATing my LAN, but how do i find out if my ISP is using a carrier-grade NAT (obviously, without asking them)?

I heard that port forwarding is not working in multi-level NATs, and that you need STUN/TURN for that, and portforwarding works just fine for me, so i could assume that my ISP is not CGNing?

closed as off-topic by Ron Trunk, user36472, Zac67, Ron Maupin Mar 11 at 13:56

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "NE is a site for to ask and provide answers about professionally managed networks in a business environment. Your question falls outside the areas our community decided are on topic. Please visit the help center for more details. If you disagree with this closure, please ask on Network Engineering Meta." – Ron Trunk, Community, Zac67, Ron Maupin
If this question can be reworded to fit the rules in the help center, please edit the question.

  • Unfortunately, questions about home networking are explicitly off-topic here, You could try to ask this question on Super User. – Ron Maupin Mar 11 at 13:56
  • I never said that this is about home networking, this could very well be a company related question (it is, in fact, not about my home network.) – Flying Thunder Mar 11 at 13:58
  • CGNAT is used for residential/home networking. – Ron Maupin Mar 11 at 14:02
3

You need to connect a host to the router you have directly connected to your ISP.

Navigate to http://myip.dk/ or a similar service, that will reveal your public IP address.

Now login to your router and check what public IP address it has configured either via DHCP or static configuration.

If the two public IP addresses are the same, then your ISP is not using CGN.

If your ISP is using CGN it would typically show a WAN IP address like 100.xxx.xxx.xxx, 10.xxx.xxx.xxx. or 192.xxx.xxx.xxx.

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