networking - Python: check whether a network interface is up

Question

In Python, is there a way to detect whether a given network interface is up?

In my script, the user specifies a network interface, but I would like to make sure that the interface is up and has been assigned an IP address, before doing anything else.

I'm on Linux and I am root.

Answer 1

The interface can be configured with an IP address and not be up so the accepted answer is wrong. You actually need to check /sys/class/net/<interface>/flags. If the content is in the variable flags, flags & 0x1 is whether the interface is up or not.

Depending on the application, the /sys/class/net/<interface>/operstate might be what you really want, but technically the interface could be up and the operstate down, e.g. when no cable is connected.

All of this is Linux-specific of course.