Chris, Thanks a lot for your answer !
I finally understood that with podman the concept of "pod" + exposed ports solved what I wanted to do, it works perfectly : at the time I did write the first email, I used podman exactly like I used docker and didn't know about "pods". It is of course a bit frustrating not to have understood these differend kinds of network managements, in root or rootless mode, but at the moment it is not a real problem for what I do work on. I guess my knowledge of networks in root or user mode with linux is too superficial, and that fact explains my problems with that. But again, I have a practical solution : pods, that solves perfectly my problem.
So everythinkg is ok for me. To answer your question, I work on ubuntu 22.04 with the last supported version for ubuntu, that is podman 3.3.4. But for the time being, my problem is solved.
However I wanted to ask (if I can) about rootless design : by default, servers working with ports below 1024 can only run root mode. The system can however be configured to overcome that, but I guess that if there is this protection by default it is for a good reason, even if I don't know it. So the ports I expose, outside the pod, on the local host of my ubuntu host, are always > 1024. For example, let's say I use the :80 inside a container with nginx. I do expose it as :10080. Then, to get nginx on port :80 of the physical network card, I do it IP tables, that I configure in root mode of course. Is it a good practice or is it unusefully "complex" ? Or is there any better practice to do that ?
Best Regards,
Mike