I recently got several models refusing to answer my question about how to write from another process into an already opened file descriptor. They all initially gave me "that's illegal, stop hacking" even though it is clear, that it is on the same machine and user, with a program I compiler. (Ended up just attaching gdb.)
You can try opening /proc/foo/fd/bar - even though it appears as a symlink, opening it is more like dup'ing the file descriptor, not like opening the underlying file
Yep, this control server thingy I was trying to get it to implement was entirely local. In theory it could be used over the network, or tailscale... But I have no idea why anyone would do that, and I may consider just removing the address part entirely since the entire point is to debug the testbed, verify measurements and physical modelling, etc., and not to be some secure control endpoint or something.