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Cisco RV325 assigns internal ip to dynamic dns

DdeCarvalho3899
Beginner
Beginner

I recently purchased and configured a Cisco RV325. I need to use the dynamic dns option, which I have used in various other routers before. However, after following the setup process, the ip address I see at the bottom of the WAN dynamic dns configuration windows is the local router ip address (in our case it is not a local router because it is a wireless internet service via anthena). When I look at the ip address that the dynamic dns service provider (No-ip) shows as connected with that host, it is also showing my internal ip address. Something is wrong here. It should be showing my external ip address on both ends.

22 REPLIES 22

Thank you again. Huhhh, I am surprised that you would say that the router is doing what it is designed to do. What is the point of creating the DDNS configuration option if it is not able to look up the stream and find the external IP on each WAN, regardless of the type of internet gateway or router that is connected to each port? DDNS is meant to provide a way to offer a public presence for needed services without having to purchase a static IP. We do have one service we need to access from outside. That is why we want to configure DDNS. Everything else is working fine.

 

All I can say is that I've worked with multiple vendors (Cisco, Juniper, Palto Alto, and even PFsense) and haven't come across one yet that does an upstream query for its public IP. They all report the IP configured on the WAN port which is typically given out via DHCP by the ISP.  Unlike DHCP on a LAN where the client usually renews its lease with that same IP, ISPs typically change it every lease period. 

 

My guess is that the reason they don't do it is that the upstream method to obtain that IP (google, whatismyip, ipchicken, etc) isn't in their control and if those providers changed urls or the the query format it would would require firmware updates to fix it. That's too much trouble. Where as an open source software such as the Dynamic Update Client can easily be refreshed with a yum or apt function. Additionally you would still have the very complicated issue that the upstream router is NATing which means that have to configure port forwarding on the upstream device and that NATing device isn't always under your control. Most people would have the router directly connected to the ISP with dynamic public IP, which is what the DDNS client is designed to do.  

**Mark all helpful posts and solutions**

I appreciate the response. I think your response confirms what I said about how it does not make any sense for a dual wan router to offer DDNS configuration options if it cannot find the public IP address behind the internet gateways. I have configured DDNS on routers from Netgear, DLink and others, with a single wan, and they work fine.

So, here is another service, configured on a Netgear router at a different location, single WAN, behind a router, which has been working for a few years. I still think the Cisco router is not doing what it should do, if it is going to offer DDNS options. Anyone at Cisco able to clarify? Thıs is my first Cisco router, and I am about to return it.

 

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I guess you know DDNS does not work with private IP addresses.  Private IP addresses are not routable on the internet.  

If you are sitting behind another router you will only get what that router hands your router and that will be a private LAN address in the first router’s subnet.  If you are sitting behind a cable modem/router/switch that is not in bridge mode it will be the first router and the gateway receiving the public address so it needs to be in bridge mode so the public IP is passed to your router and the cable modem/router/switch is then transparent.

 

I would assume the other routers you’re testing and giving as examples are behind modems that are in bridge mode and no other routers ahead of them.  A router can only report what it is given and if it’s sitting behind another router and receives a private ip in the first router’s lan segment that’s what it will report, that’s all it can report since it can not know or query what anything ahead of it is receiving. 

I sure know private ips are not routable on the internet. That is the whole struggle here to figure out how to get the DDNS configuration on this Cisco to show my public ip.

It can only show you what it receives. If it is not the gateway to the wan and receiving the IP from the ISP it can’t give you the public address, only the address it receives from devices up stream, the next hop between itself and the WAN.
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