How to assign public IP to a device plugged into the LAN port of a Wifi router

I have these two public IPs from my ISP. As an example, let's say the two IPs are: XXX.XXX.XXX.180 and XXX.XXX.XXX.181. They are on the same range and right next to each other

When I access the GUI of my ASUS RT-AC68U router, it says on the network map that my WAN IP is: XXX.XXX.XXX.180, which is one of the two public IPs given by my ISP.

Is there a way to assign the second public IP (XXX.XXX.XXX.181) to a device connected to the ASUS router's ethernet port? If yes, I would be very grateful to know how.

I have been agonizing over this for days and I have called ASUS tech support to no avail.

dribble

Posted 2014-10-16T02:18:48.660

Reputation: 31

No, only a very high grade router would support multiple WAN ip addresses or multiple WAN ports. NAT assumes that the traffic is coming in on the WAN port, and is then forwarded to the LAN host. so the first thing you need to tackle is how to get both public IPs active on the WAN side of your router. once thats done, you can configure forwarding either by port or DMZ to expose the lan host. – Frank Thomas – 2014-10-16T03:55:17.617

1your cheapest and most secure approach would be to install a switch and second router behind your ISP box side-by-side with your existing router. then attach the server to the new router, and statically configure both routers WANs with the desired public IP. then set up DMZ forwarding on the second router, to expose your server. – Frank Thomas – 2014-10-16T04:11:35.427

Thank you @FrankThomas! I guess I have to invest more on this setup. :) – dribble – 2014-10-16T04:20:32.147

Hi @FrankThomas! Just an addedndum... I do not know if this matters, but the RT-AC68U is being advertised as having dual WAN. It only has 1 WAN port though. Just trying out my luck as we are already stuck with this router. :) – dribble – 2014-10-16T06:56:39.097

in that case, I would contact asus for support, or download the manual. it may be that the dual wan feature is only for a specific model in the line/family, or they may provide you a means to add multiple IP addresses to the wan, even though it only comes from one source. It may work yet! – Frank Thomas – 2014-10-16T11:54:09.593

@dribble The 'dual wan' feature of the AC68U is not used this way... You can define LAN 4 as a WAN port for second backup internet connection, although with alternative firmware like DD-WRT you might be able to make this work. To be honest, Frank's suggestion of a switch and second router would likely be the easiest to implement. – acejavelin – 2017-03-20T03:01:58.180

Thank you for your response. I have seen a DMZ feature on the router and the manual says this:

"IP address of Exposed Station: Key in the client’s LAN IP address that will provide the DMZ service and be exposed on the Internet. Ensure that the server client has a static IP address."

Should I key in the second public IP on the "IP address of Exposed Station" field? – dribble – 2014-10-16T03:39:51.687

No, you input the internal (LAN) IP address of the machine you want to access by public IP address. The idea is all traffic to public IP address will be forward to that machine. From the LAN view, that machine still using LAN IP address as normal.

The point is: you have 2 public IP address, I'm not sure your router support to assign 1 public IP to DMZ host or not, but at least you can use public IP to access that machine – incous – 2014-10-16T06:37:28.897

This will work for me. I'll utilize the one public IP for now and forward it uzing DMZ. Thank you for your response. – dribble – 2014-10-16T06:40:46.627

How to assign public IP to a device plugged into the LAN port of a Wifi router

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