I'm moving from one ISP, who provided a managed router that took care of things like port forwarding IPs, to a new one that does not.

So, currently I have a single, inexpensive Linksys router configured for one of my 5 external IPs and it's all working fine. However, I'd like to have one of the other external IPs go to another machine.

Is this as simple as inserting a switch between the router and the modem, and then plugging another router into that switch? What configuration settings would I need to do in order to ensure that computers plugged into one router could talk to computer plugged into the other router?

Alternately, is there a reasonably inexpensive (< $400ish) small business type router that could support multiple IPs and port forwarding (ideally with a web based interface, though that's more of a nice-to-have)?


  • Can't do what you want with the Linksys without adding a bunch of routers/switches. I played around with this idea for a while, even looking at the dd-wrt option without any luck... Do yourself a favor and buy a NAT device that can handle the multiple public IP addresses. – Dscoduc Feb 24 '10 at 19:44

I would look into pfsense. It's free...just need a computer with 2 but preferably 3 nic's so you can setup a DMZ for your public facing systems. You can also purchase one of these for about $210 with pfsense preloaded.

There are other options too if you're looking for something that's rackmounted. The Supermicro SC510 is a nice 1U case that is perfect for pfsense if you need more cpu power or want more features than a small embedded device offers.

Also to deal with multiple IP's what you need to do is to setup VIP's for each of the public IP addresses. Then you use 1:1 NAT or port forwarding to pass the traffic from each VIP to the appropriate IP on the DMZ. Network diagram would look something like this.

Internet--pfsense--DMZ Interface--DMZ Switch--(computers with public IPs)
        LAN Interface
          LAN Switch
        LAN computers 
  • 1
    1:1 Nat is what I'm using on an old SonicWall SOHO3 and it works well for the 5 external IPs that we have – quickcel Feb 24 '10 at 19:15
  • pfSense is just awesome. Try it out. It's extremely flexible for whatever your configuration may be. – osij2is Feb 24 '10 at 20:43
  • pfSense looks nice... – Dscoduc Feb 24 '10 at 20:50

You can do exactly what you want, in the way you are describing. Taking a small 5 port switch and placing it in between the providers equipment and yours and you can put a device into each port with a separate public IP. Be careful though, as you now have a single point of failure, and maybe down the road when you are using all 5 IPs, it only takes one thing to fail and everything is offline.

  • Unless you plan on having five separate NAT (Linksys) devices, you will be leaving a computer on the internet... – Dscoduc Feb 25 '10 at 15:47

I was faced with the same requirements, so I started with a Netscreen 5gt device and then ended up with a Juniper SSG-5 device. Both of these devices have a basic mode that is similar to a Linksys device for NAT, but can also be extended to have multiple vlans in addition to supporting multiple IP addresses from your ISP.

The best part about this is it's similar to your Linksys device in that it's a small appliance device that has a Web based GUI interface, along with a more powerful command line syntax.

If you look on Ebay you can find some reasonably priced units, depending on the age of the OS and whether it's from Juniper (who bought Netscreen) or the older units from Netscreen.

I have been really happy with the device and the configuration options. If you need help configuring the device just let me know... I have a similar requirement to what you described and could share my config information with you...


You can also use NATing, to me that would be the best way of doing what you want.

I tend reduce the amount of devices that have an external IP address on my network.

  • I would assume I would need router that supports multiple IPs and can do NAT, but is there an inexpensive option for that? Or can I do it with my Linksys? – Tim Sullivan Feb 24 '10 at 19:02

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