We have the situation where we need to network an isolated room in a building to a network on the other side of the building but with an 3rd party company owning all the rooms between them (they lease us our rooms). The building is 300 years old and has thick stone walls not conducive to new cabling or Wi-Fi.

At some point, a CAT5 network was installed in the part of the building we need to span, and this network happens to reach nearly all the way across the building. We want to join our "room A" and "room E" networks together, without giving the company that owns the rooms the middle (B,C & D) any visibility of our network (or vice-versa). Clearly the best solution would be to run a new cable through the other company's office, but in practice this will be very disruptive in our 300 year old building, so I'm wondering if there's a way to utilize their cabling in a secure way (for both parties).

Are there any devices which would allow us to create a private VPN which runs over the other company's network, without ever exposing either network to the other? Essentially what we're trying to do is a bit like the idea of using HomePlug adapters, but using someone else's CAT 5 network instead of mains cable.

One thing which help: We have a Fortigate firewall which could potentially act as a VPN host is in a room which adjoins their network.

  • Certainly, you need explicit written permission from the company whose network you wish to use. Many companies will not, nor should they, allow something like this on their network.
    – Ron Maupin
    Sep 14 '15 at 15:32
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Aug 12 '17 at 17:54

A VPN tunnel is a reasonable solution to this problem. I'm assuming just a few users in the isolated room, so any router or firewall with VPN capabilities would probably be fine. There would be one device in room A and one in room E.


You could simply configure a small router on your ends of the network with a site-to-site VPN and treat their network as "untrusted" as if it were any other public/Internet connection. Your Fortigate can most certainly terminate one end if you have cable between it and your other location. Just add a small router/firewall with compatible site-to-site VPN capabilities.


@NickG - The solutions can be varied but as Ron Trunk and Bobstro mentionned, a secured vpn will work. See this cisco centric link below for setting up a vpn. Note:- You could do it with harware from many other providers, even build your linux router to perform the same level of security/encryption :-) http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/867-cisco-router-site-to-site-ipsec-vpn.html

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