Router cascade w/o double NAT

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cmonty14
Posts: 6
Joined: Fri May 06, 2022 2:46 am

Router cascade w/o double NAT

Post by cmonty14 »

Hello,
based on this tutorial I started a setup of router cascade w/o double NAT.

This means primary router is setup with disabled NAT and additional routing rules.
The visualization would look like this:
clients ↔ Gargoyle router (no NAT) ↔ routing rules ↔ ISP router with NAT ↔ Internet

Actually the clients are represented in a LAN subnet (172.16.1.0/24) and DMZ subnet (172.16.11.0/24).

This works as expected.

Now I want to connect a secondary router to a free NIC of the primary router. This secondary router provides multiple subnets, e.g. Office, Guest, IoT.
The secondary router's LAN subnet is identical to primary router's LAN: 172.16.1.0/24.
This subnet is only for router access (SSH and HTTPS).

As a result the following IPs are assigned:
primary router:
LAN: 172.16.1.1/24
DMZ: 172.16.11.1/24
eth1: 172.16.0.1/30
WAN: 192.168.1.2/24

secondary router:
LAN: 172.16.1.2/24
Office: 172.21.10.1/24 (VLAN)
Guest: 172.21.20.1/24 (VLAN)
WAN: 172.16.0.2/30


The current issue is:
No internet access from secondary router, means I cannot upgrade software packages.
DNS on secondary router works, though.

I assume the issue is related to the configuration of the primary router.
eth1 is not assigned to a firewall zone, this means there are now firewall rules etc. related to this NIC and subnet 172.16.0.0/30.
But I don't understand how network traffic on this subnet would be routed to WAN interface of primary router.

Can you please advise how to troubleshoot this issue?

ispyisail
Moderator
Posts: 5018
Joined: Mon Apr 06, 2009 3:15 am
Location: New Zealand

Re: Router cascade w/o double NAT

Post by ispyisail »

It appears that your configuring via command line?

Question: If this is the case why not use openwrt instead of Gargoyle?

Gargoyle is all about the GUI

Lantis
Moderator
Posts: 6351
Joined: Mon Jan 05, 2015 5:33 am
Location: Australia

Re: Router cascade w/o double NAT

Post by Lantis »

This setup sounds incredibly convoluted and I’m not sure what the end goal is.
Maybe a picture would help?

Either way, you’re way out of my expertise and I expect most other people on the forum. You might have more luck in the openwrt forum as the question is purely a routing one.
http://lantisproject.com/downloads/gargoyle_ispyisail.php for the latest releases
Please be respectful when posting. I do this in my free time on a volunteer basis.

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