Authorization policy: Allow access to only one non-meshed client

[leam18]

Hi! I m setting authorization policies in my application stack, but not all pod are meshed.
So I need to restrict access to meshed pod to only receive traffic from a non-meshed pod.
I read the documentation and seems the only way is using NetworkAuthentication by specifying a CIDR block or the pod's IP in CIDR notation, but the first approach will allow all the pods that share that CIDR block, and the second approach will work until the pod gets restartted or terminated, because it will change the IP.
Is there another way to accomplish this?
Thanks!