I have 4 ethernet devices contained in one system. There are several systems connected on the ethernet network; I would like to use the exact same ip addresses internally with in each system. . I can expose one device to the outside world using another network interface. If they were all computers I know I can do this with a simple switch and a separate nic on one computer with routing disabled.

With this in mind : System A has 4 NIC's, 11, 12, 13 System B has 4 NIC's, 11, 12, 13

How can I isolate these "system" private networks from each other and also allow access to them from the outside world via a network connection. [Theses are not computers - they are network devices] for now just think of them as NIC cards. How do I isolate these two systems and yet provide a path via the lan or internet connection for remote access to the devices with in the systems.

Could a managed switch do this for me?

EDIT 4-12-2016 : 17:17 EDT USA

I need to be able to keep the 4 ip addresses inside the system private - and the purpose of the switch inside the system is exactly that - the 4 devices with private ips are linked together on the switch - on their on subnet. I will need to be able to access those devices from outside the system via the company LAN - because there are multiple systems with exactly the same IP's internally this means I can not expose these to the LAN. So How can I gain access to them with out exposing them to the LAN - but also do this from the LAN. If I need to add something to the system to do it - I will do that - but I am not sure. If the devices were computers I could do this - and have done this before. But they are not computers - they are dumb devices with an interface. So with 4 devices plugged to a switch they can communicate together. Now I need to be able to have access to each one from the LAN. If I set up a PC internally - I would need to load all the required software for programming each device on the thing and perform that with Teamviewer or VNC , I do not want to do that.

Could I use a managed switch and use something like IP forwarding to via that switch - giving that switch a specific IP and the devices connected to it on their own private lan?

  • Routers route between networks, switches don't since they don't understand IP. Routers may have ACLs which allow/disallow traffic between networks. Firewalls protect networks. Some routers may have firewall modules, and some firewalls can also route. Private address will never be routed on the Internet since ISP will drop traffic with private addressing.
    – Ron Maupin
    Apr 12, 2016 at 19:18
  • @Ron Maupin - I understand the private IP address is exactly that. I am trying to do something I know I have done with PC's - but these devices are not PC's and the requirements are a bit different - the devices need to be remotely managed - with software that is too expensive to license per system. I have updated my question with more information.
    – StixO
    Apr 12, 2016 at 21:21
  • To get from one network to another, you need to route. I'm not saying the devices can route, I saying you need a firewall/router, additionally, to accomplish what you want. IP is a layer-3 protocol, and switches operate at layer-2, so you need a layer-3 device (router/firewall) to do this.
    – Ron Maupin
    Apr 12, 2016 at 21:27
  • @Ron Maupin - yes routing is what I need - but then the problem comes in how to keep those private IP's in System1 from being visual to the private IP's in System2 - how is it possible to do this with just a router? In the PC scenario - apps were on that PC and routing was disabled on that entry point PC. So as long as one accessed the system there - they can run that system and access the others from that point without exposing the internal ip's.
    – StixO
    Apr 13, 2016 at 15:18
  • You need a router with ACLs or a firewall. You can specifically permit/deny traffic from addresses or networks to addresses or networks. This is very routine.
    – Ron Maupin
    Apr 13, 2016 at 15:35


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