[arielb1]

How is this supposed to work? How will the packet destined to the WiFi IP address get to the Ethernet interface?

[loeg]

The kernel internally routes it to the logical IP address. Since it's an internal address, the packet never goes down to the NIC.

[arielb1]

What's the configuration you're talking about? In the Wifi+Ethernet case, how do the routers know to send the packets towards the "right" interface, without the computer having the "right" IP address?

I mean, suppose the computer has WiFi IP address 10.0.0.3 & Ethernet IP address 10.0.0.5, then after NAT the return packets will go to 10.0.0.3, and therefore should go to the WiFi interface, not to the Ethernet interface (or, if they don't, how do they know which interface they should go to?).

[Dylan16807]

I believe you're interpreting the question wrong.

This isn't "How does the packet get fixed?", it's "How did a packet going to the WiFi IP get transmitted to the Ethernet port in the first place?"