pfSense

I'm not certain there is a good way to do this in a way that wouldn't break other, valid behavior. Working with sysctls that get renamed makes this fuzzy, for example, kern.ipc.somaxconn can still be used in some cases to write a value even though the OID was renamed to kern.ipc.soacceptqueue, but it does not show up in sysctl -a output using the old name, just the new name. In that case it's best to move the value to the new name, but the old name still does work, just not in an ideal way.

Rejecting these could also prevent a user from staging tunable settings for new hardware before making a physical change. The tunables wouldn't be present because the hardware isn't there yet.

Maybe we could warn the user but I wouldn't go so far as to prevent such OIDs from being added.