DSL-AX82U-AX5400 Full-cone NAT

[TrebleTA]

So I've noticed that my DSL-AX82U-AX5400 under WAN Internet settings I can not select Nat type.

So I think I can enable by typing in SSH

nvram set nat_type=1
nvram commit

Reboot rooter.

And to revert back its

nvram set nat_type=0
nvram commit

Reboot router.

Is that correct also how would I test it's working?

 

[Yota]

If you want to do serious testing, you need to have servers that actively send UDP and TCP requests to your LAN.

But there are some simple but possibly unreliable ways out there, and here's an Android app that claims to do this kind of testing: https://play.google.com/store/apps/details?id=md.tabuci.stunclient


This is a browser-based test page, but reliability may be further reduced by browser security policies: https://tomchen.github.io/symmetric-nat-test/


Note that including this setting in nvram does not mean that your router supports it, many routers share the same nvram variables, but some variables are only valid on a specific router, especially the NAT type, it needs both hardware and software support to be valid, If you can't see it in your GUI, it usually means it probably won't work for you.

Good luck.

 

[TrebleTA]

I'm told it is by asus, but they are slow to reply. Is there a way to check, what the setting is in nvram is and to test as you say?
Also are the codes above correct?

 

[Yota]

Yes, the nat_type variable is used to adjust the NAT type, 0 for Symmetric and 1 for Full-cone on supported models.


I just tested with the latest version of Firefox on my laptop and the site correctly reported the NAT type after I changed the AC86U setting.

 

[TrebleTA]

So normal nat= Full-cone nat
Also is a reboot needed?

 

[Yota]

No, there are 4 NAT types out there, sadly the site can only report two.

They refer to Full Cone NAT, (Address-)Restricted Cone NAT, and Port-Restricted Cone NAT as Normal NAT.
So you are not sure if you are Full Cone NAT


Also you can try the app, it might report four different types of NAT.


I recommend restarting the router after changing this nvram.

 

[TrebleTA]

I havent had time to test but last I entered nvram to full-cone and it showed normal, so guess it ment I'm under a full-cone.

Shame I need to reboot was thinking nvram commit was like apply. Am new to nvram setting(ssh), so still learning

 

[ColinTaylor]

...there are 4 NAT types out there...

This is technically incorrect. RFC3489 defined 4 NAT types but that is now obsolete and has been replaced by RFC5389. The use of "NAT types" is now depreciated.

RFC 5389: Session Traversal Utilities for NAT (STUN)

Session Traversal Utilities for NAT (STUN) is a protocol that serves as a tool for other protocols in dealing with Network Address Translator (NAT) traversal. It can be used by an endpoint to determine the IP address and port allocated to it by a NAT. It can also be used to check connectivity...

datatracker.ietf.org

Furthermore, classic STUN's algorithm for classification of NAT types was found to be faulty, as many NATs did not fit cleanly into the types defined there.

 

[TrebleTA]

This is technically incorrect. RFC3489 defined 4 NAT types but that is now obsolete and has been replaced by RFC5389. The use of "NAT types" is now depreciated.

RFC 5389: Session Traversal Utilities for NAT (STUN)

Session Traversal Utilities for NAT (STUN) is a protocol that serves as a tool for other protocols in dealing with Network Address Translator (NAT) traversal. It can be used by an endpoint to determine the IP address and port allocated to it by a NAT. It can also be used to check connectivity...

datatracker.ietf.org

So that mean swaping to full-cone nat is the older nat type, kind of lost now

 

[TrebleTA]

A old post but, how do I check what the NVram value is, the above will change the setting but I want to view what it is by default?
Worked it out Nvram get nat_type