When root meets immutable: OpenBSD chflags vs. log tampering

It is not the same, but I do use "chattr +i" on a file (which applies the immutable attribute) on Linux to a file that otherwise would have been overwritten by programs that do not give a damn whether I want it to or not, and in my case it was easier to just make that file immutable, mainly: /etc/resolv.conf.

Are you using systemd-resolved? If so, it's actually a symlink to /run/systemd/resolve/stub-resolv.conf, and all you need to do to manage it yourself is to turn it into a regular file of your own. This is explained in the admittedly very long commented out text above the actual directives.