Has anyone thought about designating an official range of TCP port numbers which would be recommended for vty/ctrl/etc ports of processes that use Osmocom libraries and extend Osmocom CNI in various ways, but aren't official Osmocom projects?
No such idea exists, but it remains valid that you can choose any port number.
For example, in Osmocom we hand out port numbers "around" 4242, the definitive list being: https://osmocom.org/projects/cellular-infrastructure/wiki/Port_Numbers
If you'd like to run alongside Osmocom (without cfg), then you probably want to stay clear of 4000 to 4500. So you can just pick 5000 or whatever.
Even if you have a collision of default port numbers, you can always reconfigure the VTY port or IP address to listen on. For example, in our test setups, we often have multiple osmo-mgw running, and bind one to 127.0.0.1 and the other to 127.0.0.2. So even if you overload a used port number, the user will have ways to fix it.
line vty bind 127.0.0.7 ctrl bind 127.0.0.7
If we have agreement on it, we can also designate a port number or range on above wiki page as "used by project XYZ" and then hopefully future Osmocom programs will see that and choose a different port.
It does not make sense to officially designate a given port range as non-Osmocom, because each program or program-family should make their own port choices. They should not *all* use the same port range.
~N