I have an advanced routing problem here.
I need the advice of a Networking Expert or a CCNA/CCNP level administrator.
The problem can be found here:
I have changed the IP addresses to simplify the output.
As you've noticed, I have 2 networks: 192.168.0.0/24 and 192.168.1.0/24 linked to the Router.
192.168.0.0 - is an Ethernet Network.
192.168.1.0 - is a Wireless Network.
My Laptop is running Ubuntu Linux and my router is running Gentoo Linux.
I have connected the Laptop to BOTH the 192.168.0.0 net (via eth0) and to 192.168.1.0 net (via eth2).
So my routing table looks like this:
default via 192.168.0.1 dev eth0 proto static
169.254.0.0/16 dev eth0 scope link metric 1000
192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.2 metric 1
192.168.1.0/24 dev eth2 proto kernel scope link src 192.168.1.2 metric 9
The PROBLEM: When I ping the Wireless Interface of the Laptop (192.168.1.2) from the Computer (192.168.0.3) the ping DOESN'T WORK !
It travels the network up to my Wireless NIC on the Laptop but it dies there !
But if I ping the Router Interface for the WLAN (192.168.1.1) from the same machine (192.168.0.3) it works !
Pinging everything else from Laptop also works !
Being connected to 2 networks on my laptop via my physical interfaces, I have at least 2 directly connected routes.
So it's not a routing problem from what I have seen.
If I remain only on wireless and disconnect Ethernet, everything works fine.
The problem only arises when I'm using BOTH the connections at the same time.
I wiresharked my laptop on all interfaces and filtered for ICMP, and when I ping from the Computer to the Wireless Interface of my Laptop I see that the PINGs are indeed coming into my wireless interface !
But my OS does not send replies.
Only ICMP requests, no replies.
Theoretically it should receive PING on wlan interface and send it out on the ethernet interface (since my ethernet network is directly connected trough eht0). - as indicated by my Red directions in the drawing.
So it's a "ping trough one interface, reply trough other" scenario.
Before you ask, my Router is already set to ip_forward=1, beucase my laptop can sense the pings coming on the wlan interface.
Please, only reply if you understand what I am saying here, please do not "BUMP" or other stuff.
I need serious help here.
Thank you !