Apologies in advance if this question is a bit simplistic. I'm normally a software dev, however I'm the only 'IT guy' in my company so I have to deal with all sorts. Bear with me..

My company is planning on setting up equipment overseas on the premises of a third party. When we get there we will be piggy-backing onto the network of the third-party. We need control of the network which our devices are connected to in order to ensure things like static IP address allocation etc. The hard part is we don't really know anything about the network we'll be connecting to. Ideally we have everything set up so we can plug-and-play on arrival.

I think this means I need to create a subnet like I've shown in the picture, with our router acting as a DHCP server for the subnet. However, that's about as far as I got.

  1. Is this the correct way to achieve such an outcome?
  2. What sort of device do I need to achieve this? Router? Switch?
  3. How can I best set up the router/switch so that we can get as close to plug & play on arrival and avoid conflicts with the existing network?

Thanks my idea of a network diagram

  • Do you need to communicate with hosts on the foreign network, or are you just using it to get out to the public Internet?
    – Ron Maupin
    Oct 31, 2015 at 6:13
  • Just using the internet connection.
    – DBrowne
    Oct 31, 2015 at 6:14

1 Answer 1


Since you are simply using the foreign network to get access to the public Internet, you can get an IP address and subnet for your router from the foreign network, but you need to know beforehand what the address and subnet are.

You can run NAT on your router to assign your inside subnets as any private address subnets which do not belong to the foreign network's subnet to which your NAT router is connected.

I strongly urge you to also run a firewall, either on your router, or as a separate box.

This will allow you to send a turnkey network, but only if you can be assigned your outside NAT address and subnet prior to shipping the equipment. If you happen to use a subnet which falls in the subnet to which your NAT router is attached, you will have problems. That's why you want to know this up front.

  • Thanks very much. I suspected as much with regards to the subnet clash issue, however that should be a pretty straightforward config adjustment if it arises. Thanks for the firewall advice. I'll definitely heed that. Sorry I don't have enough rep to upvote.
    – DBrowne
    Oct 31, 2015 at 7:25
  • 3
    Choosing a "non-default" private IP space can greatly reduce the odds of a clash with the outer network (as well as being a pretty straightforward config adjustment if that strategy fails - but there are large swaths of largely unused private IP space - pick an oddball part and you'll probably be all set.
    – Ecnerwal
    Oct 31, 2015 at 13:13

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