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How do I map my external IP to a new server?

NineThirtyAMPST

Junior Member
Sep 30, 2016
6
0
1
I would really appreciate help on this.

I have a server (server 1) that is up and running using an external IP. We just received a new server (server 2) to replace the old one. We need the external IP that was mapped to server 1 to be mapped to server 2 so we can decommission server 1. My problem is that no one at my company remembers setting it up, or where that external IP configuration is located.


Our network consists of:

· Comcast Business Gateway – I checked the GUI

· ASUS Wireless Router – I checked the GUI (just in case). Edit: Only used as WiFi access point.

· Check Point 2200 Switch/Firewall – I checked GUI (really thought it would be this one.)

· D-Link unmanaged switch

· An unbranded dumb switch with no markings or indicators

· Server 1 – Windows Server 2008

· Server 2 – Windows Server 2012


What I have already tried:

I logged in to the GUIs of the Gateway, ASUS router, and the Check Point. I looked for that public IP mentioned anywhere in the GUIs. – no success

I contacted Comcast Support. They said that everything is handled on our end.

I contacted Check Point support. They wouldn’t help because our subscription ended.

I tried switching the MAC addresses (spoofing) of the two machines just in case the public IP was configured to point to a specific MAC address. – no success

I tried switching the internal IP addresses of the two machines just in case the public IP was configured to point to a specific internal IP. – no success

I appreciate any insight.
 
Last edited:
Feb 25, 2011
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The IP switcheroo should have worked. Routing rules are 99% of the time based on mapping an external IP/port combination to an internal IP address.
 

John Connor

Lifer
Nov 30, 2012
22,840
613
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Comcast's IPs are so-called sticky IPs. They are bound to the MAC address. I can change my Comcast IP using the MAC address clone feature in the router. It would be very hard to maintain the same IP you had unless you cloned the MAC of what ever the last node is that faces external WAN. I guess that would be the server. In which case server 2 needed to have the same MAC as server 1 to keep the same IP. And at that it may not even have worked.

What OS is the server running? I'm trying to learn more about Linux myself, but I'm sure there is a MAC address command.
 

mxnerd

Diamond Member
Jul 6, 2007
6,076
872
126
Guess your ASUS router is only used as WiFi access point. All you need is change Check Point 2200 firewall port forwarding configuration : that is, port 80 & 443 (http & https) traffic to the correct internal IP of your new server. You don't need to know your public IP.

Want to know your public IP? visist http://www.ipchicken.com and you will get it.
 
Last edited:

ch33zw1z

Lifer
Nov 4, 2004
33,695
12,476
146
Sounds more like you have one static external ip, due to it being com cast business, but still using port forwarding for the internal network.

Either way, what we need is some more info.

Start with "ipconfig /all" from both servers and put in thread.

Also, it would help to start mapping the network, even on a piece of paper, to get a physical layout to display as a reference.
 

mv2devnull

Golden Member
Apr 13, 2010
1,374
81
91
Also, it would help to start mapping the network, even on a piece of paper, to get a physical layout to display as a reference.
This.

My guess is that the ISP cable arrives to the Gateway and internal cable continues from Gateway to the Server.

My guess is that your internal network does not have public addresses. Therefore, you have NAT and the NAT device has a port forwarding rule that redirects (some) incoming traffic to the Server. The rule does not have public address, but it has Server's address.

I hope that you have DHCP to give addresses to the internal devices. The DHCP most likely is set to give specific IP to the Server (the same IP as in the port forward rule). Therefore, update the DHCP config to give that IP to the new Server instead, and you should be good.
 

NineThirtyAMPST

Junior Member
Sep 30, 2016
6
0
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Either way, what we need is some more info.

Start with "ipconfig /all" from both servers and put in thread.
I have the ipconfig/all for both servers, but can I ask you what specifically you are looking for? That way I don't flood the thread with super long posts.
 

NineThirtyAMPST

Junior Member
Sep 30, 2016
6
0
1
I hope that you have DHCP to give addresses to the internal devices. The DHCP most likely is set to give specific IP to the Server (the same IP as in the port forward rule). Therefore, update the DHCP config to give that IP to the new Server instead, and you should be good.
We don't use DHCP for our servers, we manually assign IPs to all hardwired machines. We only use DHCP for wireless, say if a laptop connects to the network.
 

mv2devnull

Golden Member
Apr 13, 2010
1,374
81
91
Surely you do know that you can give the same IP to a server persistently with DHCP too?

I gather ...
* the old server does not have public IP
* the old server is connected to the firewall
* the firewall is connected to the gateway
* the gateway is connected to the external cable

Is there a "DMZ" setting on the firewall?
 

NineThirtyAMPST

Junior Member
Sep 30, 2016
6
0
1
Surely you do know that you can give the same IP to a server persistently with DHCP too?

I gather ...
* the old server does not have public IP
* the old server is connected to the firewall
* the firewall is connected to the gateway
* the gateway is connected to the external cable

Is there a "DMZ" setting on the firewall?
There is a DMZ setting on the firewall. It is set to manual configuration, and the fields are empty. The status of the DMZ connection is also currently "disabled".
 

ch33zw1z

Lifer
Nov 4, 2004
33,695
12,476
146
I have the ipconfig/all for both servers, but can I ask you what specifically you are looking for? That way I don't flood the thread with super long posts.
need to see what your configs look like, trying to get an idea as to what's going on.
 

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