Configuration file monitoring - reporting content changes

[Burn Alting]

All,

I am interested in any Linux based capability that will monitor
identified files and report on actual changes to the monitored file. I
know there are methods of recording that the file has been changed (e.g.
aide and/or monitor writes via auditd), but I want to know what has
changed ... basically something that would provide a 'diff' like output.

Now there are tools like Samhain that will record the content changes of
a file that is <= 92000 bytes in size, but I am interested in a more
lightweight solution ... perhaps a simple inotify(7) based utility that
perhaps maintains a copy of the file(s) in core (in compressed format)
and based on inotify() returns checks for changes and reports (somehow
yet to be defined) the before/after changes.

Is there anything 'out there' that list members are aware of?

If not, would the following utility be of interest? On startup, load the
monitored file(s) (saving a compressed copy in memory). Then, using
inotify, monitor for changes and if so, emit some kind of record
defining the change and change the compressed in-memory copy. If so, is
our mailing list and the contributed portion of auditd an appropriate
repository for such a tool.

Naturally, such a tool would be supported by appropriate auditd
monitoring that will take care of changing file attributes etc and file
writes. That is, auditd tells me who and the utility tells me what.


Regards
Burn