hwo to update dynamic dns host behind the rourter?

shams · 04-29-2015, 12:52 PM

I use ubuntu vivid, it is connected to wifi network with a 3g wifi modem, i am running local web and mail servers, the wifi modem get deffernt external ip addresses in every new connections, i have the dynamic dns accounts with freedns.afraid.org and dnxexit.com, when i run their clients to update the hosts ip in the their servers, they didn't get the wifi modem external ip address but instead they get my 3g isp ip address updating the hosts in dynmaic dns servers.
how can solve this problem?

MQMan · 04-29-2015, 01:36 PM

Is the external IP of the modem reachable from the internet. It looks like the isp might be doing some form of NAT.

Can you provide some, very slightly masked, examples of the 2 IPs.

Cheers.

jefro · 04-29-2015, 02:26 PM

Yes, the public ip is what you are interested in. You follow that ip to the named web site.

To get your local systems you nat and usually set static the local IP addresses in the router or at computer.

shams · 04-30-2015, 11:49 AM

Thanks for replies, the router external address is also private address in the range of 172.16.0.0 - 172.31.255.255 and the daynamic dns clients gets the isp address is 180.222.x.x.

MQMan · 04-30-2015, 12:31 PM

Quote:

Originally Posted by shams

Thanks for replies, the router external address is also private address in the range of 172.16.0.0 - 172.31.255.255

By router, do you mean the wifi modem you referred to in the original post or do you have a router behind that modem.

If it is the same device, then the ISP is doing it's own NAT and you're not going to be able to route from the internet to your router/modem.

Cheers.

suicidaleggroll · 04-30-2015, 12:55 PM

I don't believe you can get outside access to 3g devices. The ISP does their own NAT and you can't forward through it.

If you have access to a 3rd party server that's not on 3g, you could have your web/mail server open a reverse SSH tunnel to the 3rd party server, and point your domain to the 3rd party server. Any incoming connections on your domain will hit the 3rd party server, and then pass through your reverse ssh tunnel to your device on the 3g network. This tunnel will have to be initiated and maintained on your 3g server though (bringing it back up whenever it goes down, etc.).

It wouldn't be the most robust/reliable of setups (neither is 3g for that matter), but it might do for your application.