Our business has, until recently, used dynamic IPs through our ISP (AT&T) for our office network. Recently we have adopted an external network application which requires the use of a handful of static IP addresses so it can identify and whitelist traffic coming only from certain computers in our office.
Our network infrastructure consists of a DSL switch (Netopia 3346N), a firewall (Netgear FVS114), and various workstations, servers, and peripheral devices.
I've acquired a small block of static IPs through our ISP (x.x.x.144-151), and the Netopia switch has occupied one of them (150). My goal is to assign computers on the internal network to two others (145 and 146, at the moment) and use these computers to interface with the external service.
The internal network has two subnets. The first is 192.168.1., which contains the DSL switch and the firewall. Behind the firewall, we have 192.168.0., which includes all the other devices in the office. I can access the Internet from the office computers; when I hit whatismyip, it shows all of them as coming from x.x.x.150. This is what I expected so far.
Now, on the Netopia 3346N, I have set two IPMap entries for the computers that I want to have static IPs outside our LAN. The IPMap entries are set with the internal address as 192.168.0.3 and external x.x.x.145, for example. On my home network (using a similar DSL modem but no firewall) this is sufficient to produce the desired behavior.
The mapped computers can still access the Internet, but the mapping isn't happening; they are showing up on x.x.x.150 like everything else, and ping requests to their static addresses don't go through (even if I DMZ one of them in the firewall).
My only thought is that the fact that the mapped computers are on a different subnet from the DSL modem is confusing the IPMap function. If this is the case, I'm not sure how to fix it without discarding my firewall (which I want more than ever, now that I'll have static-mapped computers on my LAN). I've played with static routes in the firewall, but I admit I've never had to deal with them before, and I haven't been able to make it work.
Can anyone give me some ideas of how I might make it work?
We took the firewall out of the network, changed the DSL switch to the same address that the firewall used to occupy, and the IPMap works. The problem is definitely somewhere in the firewall.
The only NAT control on the firewall is a toggle that turns it on and off; I can't change any of the settings directly.
Unfortunately, we haven't been able to make the static routing work properly with the firewall in place. We're considering replacing the Netgear firewall with something that gives us a little more control over the NAT process.
We're still looking for advice, since I'd prefer not to spend more money to fix the problem. If anyone has a brilliant idea of what I'm doing wrong, please let me know.
