[Frage] Turn off firewall or add rules for routed subnet

[frater]

I have used a 7590 as both NAT-router and static router for a /30 network.
This enables me to use a 2nd router to provide an "independent" connection.
I was expecting the Fritz!Box to just statically route traffic coming from that 2nd router.

Alas, it turns out there's a firewall in-between. AFAIK only for incoming traffic.
A firewall which I can't control using the WebIF.
The WebIF only takes settings for NAT'ed LAN-IP's.

What commands can I give to allow incoming traffic like TCP, UDP and ICMP for those foreign WAN-IP's?



The Fritz!Box logs in using PPPoE and obtains the WAN-IP x.x.153.57

Network: x.x.153.56/30 - subnet provided by ISP
Fritz!Box: x.x.153.57 - NAT-router for 192.168.x.x/24 network
Cisco: x.x.153.58 - Foreign device connected to the LAN (it uses x.x.153.57 as its gateway)
Broadcast: x.x.153.59

In the IPv4 section I filled in:

x.x.153.56
255.255.255.252

 

[frater]

This has been solved (other thread)

Just like port forwarding for NAT-devices, a device on the subnet should appear in the devices list.

It didn't appear on mine because the Fritzbox still "knew" that mac-address from years back when the external device (a Cisco) was configured behind the NAT-network.