One of my client's site was recently hacked and we only found out about it when they used the site themselves and found it was redirecting elsewhere. We've changed FTP passwords and restored all the files so I'm pretty sure that the site is now clean.

What I'd like to do is set up some sort of system that can look for new or altered files on a website and notify me if they are found so I can fix the problem ASAP. There's a nice write-up on how to do this using PHP at http://phpmaster.com/monitoring-file-integrity/ but I have about 100 client websites on shared hosting and setting this up on every site seems an inefficient way of doing things.

I thought that a more efficient way would be a program that runs on my local Windows system that FTP's into each site, gets a file list (including date last modified and file size), and then stores all of this information and does comparison checks and notifications off-line. That would move all of the processing off the web sites and on to my local system.

I've tried looking for software like this but I can't find anything. Can anyone suggest anything?