Can someone tell me if I am approaching this wrong?
I created .iso images of all of the original SuSE 9.1 Pro CDs and DVDs. Now I am wanting to compare the MD5 checksums for the CDs with that of the iso images. This worked great on the 1st 2 CDs but has gone south since.
I am using the command:
md5sum /dev/cdrom
The odd thing is when I started getting odd readings, I ran the sum 3 times consecutively on the same CD and got 3 different values: :~$ md5sum /dev/cdrom 38e72a5efd89851ceb7349d7406ac035 /dev/cdrom :~$ md5sum /dev/cdrom 31dea26a1f7e5fd2c4f8a384c1bef8e0 /dev/cdrom ~$ md5sum /dev/cdrom 9c1e9e02ecd5401c87ac2ca59c69ee92 /dev/cdrom
Shouldn't I get the same value each time? Am I misunderstanding the MD5 sums?
Your right, something is wrong. ===> More than you wanted to know below ;-) One thing you might try is: dd if=/dev/cdrom | md5sum That way dd can tell you how many blocks of data it is reading and you can confirm the whole cd is being read each time. Finally, it you are really curious you can install dcfldd and use it to show the md5sum for each chunk of the cd. dcfldd == DOD Computer Forensics Labs DD I think the command would be dcfldd if=/dev/cdrom of=/dev/null hashwindow=1M hashlog=/tmp/cdrom.hashlog You could run that a couple of times, then diff the hashlogs to see which part of the cdrom is flackey. one place to find dcfldd is http://sourceforge.net/project/showfiles.php?group_id=46038 Hope that was interesting if nothing else. :) Greg -- Greg Freemyer