Current situation:

The internet available to me is a shared router that I do not have administrative access to. If really needed I could reset the password but I rather not. I plugged in a network cable and plugged it into the WAN port on my own openwrt/lede router. This gives me a semi-functional but secure network where I have a firewall. However this is a double NAT, which breaks some programs.

What I want:

I want to assign my own network the IP's given from the shared network( where I keep my firewall enabled. In a way this is similar to assigning public IP's from your ISP to your whole LAN while having a firewall. Simply bridging the WAN and LAN side works but I lose the firewall in this case, which is missing the point. I simply do not trust the other tenants.

Unfortunately my knowledge about how to route networks is limited to NAT so I don't really know how to approach this(sidenote: any good tutorials on routing?). I did find this: https://lede-project.org/docs/user-guide/firewall_configuration#stateful_firewall_without_nat.

But that doesn't work. I simply lose internet from my LAN side when I disable masquerading(which I assume is NAT)

  • Unfortunately, questions about consumer-grade devices are explicitly off-topic here. You could try to ask this question on Server Fault for a business network, or on Super User for a personal network. Also, understand that NAT has nothing to do with the firewall function. Firewalls can operate fine without NAT, it is just that a firewall is often a convenient place to NAT. NAT can also be run on a device that is not a firewall. NAT is just a kludge to extend the life of IPv4 until IPv6 is prevalent.
    – Ron Maupin
    Jun 2 '17 at 16:16

If ou want to get traffic from the multi-tenant network to your own using the addresses given to you from the multi-tenant subnet you'll need to turn off NAT as you have done and then enable proxy-arp for the addresses you want. However this is overkill, I don't know what applications won't work across a "double-NAT" as you call it. Unless you are somehow processing the network traffic between the NAT devices, then what difference can it make, one NAT or two?

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