On Tue, 2015-07-21 at 13:59 -0400, Steve Grubb wrote: > On Tuesday, July 21, 2015 10:38:31 AM John Dennis wrote: > > On 07/20/2015 07:08 PM, Steve Grubb wrote: > > > On Monday, July 20, 2015 09:53:47 PM Burn Alting wrote: > > >> I am interested in any Linux based capability that will monitor > > >> identified files and report on actual changes to the monitored file. > > > > > > I know of nothing that does this. But as long as the list of files is > > > limited, it doesn't sound like a hard program to write. > > > > > > Any one else with an opinion? > > > > Yes :-) I'm not so sure it's an easy program to write and be robust in a > > variety of scenarios. I know because I wrote such a program once. The > > basic problem is most people think in terms of monitoring a file by name > > (e.g. it's pathname). But inotify operates on inodes, not filenames. If > > that file is subject to any variety of log rotation strategies or > > modifications by a configuration manager whereby the file is renamed or > > moved to a different directory then any program using inotify to monitor > > the file needs to become reasonably sophisticated and be able to track > > those changes. It is entirely possible for two processes to have opened > > the same file by name but have them be 2 different files (e.g. after > > opening the file path is modified but the process still has the original > > inode open, now a 2nd process opens the same filename but gets a > > different inode). Conflating inodes with filenames can lead to > > unexpected results and if the purpose is some sort of security > > monitoring it will be important these issues are accounted for. > > I recently was doing some experimenting with the fanotify API. In my mind, I > think its likely to be better. But it has limitations such as mmap'ed file > may > not generate a modify event. So, if I were going to do it, I'd start there. > But you do raise a whole lot of good points. My guess is this would watch > config files which logrotate wouldn't apply. But yes, editors do open a temp > copy and then do a rename. In my experimenting, I didn't bother to see how > fanotify handle renames. (You would think its a modify event.) > > -Steve
I suppose one could follow tail(1)'s lead and monitor via a combination of inotify() supplemented by file, path and inode monitoring as well. Perhaps not elegant, but it may do the job. Burn -- Linux-audit mailing list [email protected] https://www.redhat.com/mailman/listinfo/linux-audit
