How to route from an outside IP to an bridged interface?

Zach

1/17/24, 5:34 PM

edit: Just to clarify my topology, everything is local and behind my ISP gateway/router. The server and laptop both connect to the gateway on 192.168.1.0/24. GNS3 is hosted on the ubuntu server and is used to create virtualized enterprise networks. GNS3 uses a bridged virtual NIC on the 192.168.122.0/24 network so that outside devices can communicate with the virtual network. I have a static route on my gateway which directs traffic destined to 192.168.122.0/24 to the ubuntu server, 192.168.1.10.

I'm running a program called GNS3 on my Ubuntu v20.04 server, with an IP of 192.168.1.10/24, which I access using my laptop, 192.168.1.11/24. GNS3 uses a bridged interface called virbr0, 192.168.122.1/24, to connect to a Palo Alto firewall, 192.168.122.9/24, I'm running inside it.

From my laptop I can ping the server and virbr0 but not the firewall(destination unreachable). From my server I can ping my laptop, virbr0 and the firewall. And from the firewall I can ping the server and virbro0 but not my laptop. If I do a traceroute from my laptop to the firewall it arrives at the server and then gets dropped. The output of "ip route show" is:

192.168.1.0/24 dev enp9s0 proto kernel scope link src 192.168.1.10 
192.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1

Since traceroute shows the pings getting to the server I'm assuming it's an Ubuntu issue not an issue with my gateway/router.

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Zach

1/17/24, 6:19 PM

You're right, my bad. Everything is local, nothing is going out to the internet so no NAT. I'm using a consumer grade gateway/router which both the server and my laptop are connected to on 192.168.1.0/24. GNS3 is hosted on my server and allows me to create virtualized enterprise network environments. GNS3 uses a bridged interface on the server, 192.168.122.0/24, so that the server can talk to the GNS3 network. On my gateway I have a static route that points 192.168.122.0/24 traffic to the server, 192.168.1.10, so that 192.168.1.0/24 can talk to 192.168.122.0/24.

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