When you work on Network Namespaces (which is a feature Linux Kernel provides), you usually create bunch of virtual ethernet ports called as veth interfaces. The veth interface itself is a separate LK virtual network driver which offers this specific functionality. But sometimes besides veth you can also configure an optional interface called “dummy” interface. The dummy interface, just like veth (and other such virtual interfaces) is provided by LK via the driver drivers/net/dummy.c.
The interesting aspect of dummy interface is that it serves as an alter ego of the loop-back localhost (as mentioned in the tldp.org article link below). Which means you can set any valid IP and this can serve as alternate local host ip other than 127.0.0.1. So to learn more, kindly watch my complete video series on this fascinating network interface called Dummy Interface.
Refer:
Linux Kernel Dummy Interface Driver source ↗
tldp.org | The Dummy Interface ↗
So here is my detailed multi-episode Youtube video series on Linux Kernel Dummy Interface, a big picture and Linux Kernel dummy interface driver code walk.