Hi, Luca Capello <l...@pca.it> wrote: > $ wget [...]/debian-6.0.3-amd64-CD-1.iso > [...] > $ gpg --verify MD5SUMS.sign > [...] > I am not a CD expert, so a simple question: if I burn the verified image > above (debian-6.0.3-amd64-CD-1.iso), do the following commands produces > an image that will match its checksum in MD5SUMS? > > $ cat /dev/cdrom >image.iso > $ dd if=/dev/cdrom of=image.iso
I am upstream developer of a burn program. Subscribed to debian-cd list. Above method will work with CD written by write type SAO and with no padding added by the burn program. It will surely not work with CD written by type TAO, with DVD+RW, or with BD-RE. Probably not with DVD+R and BD-R. Reason is that media can deliver trailing garbage after the end of the ISO image resp. that burn programs may write padding bytes after the image. You may be lucky and no trailing garbage is delivered. But you cannot generally trust on this luck. > If not, the only way to verify that the CD bought from any vendor comes > actually from an "Official CD Debian image" is to verify the its > content. The CD image contains an md5sum.txt file > $ sudo mount -o loop debian-6.0.3-amd64-CD-1.iso /media/cdrom0 > [...] > $ cd /media/cdrom0/ > [...] > $ md5sum -c md5sum.txt && echo 'everything OK!' I wrote a shell script as alternative to this. George Danchev recently presented it to debian-cd list: http://lists.debian.org/debian-cd/2011/11/msg00034.html It determines the size of the ISO image and then pipes the appropriate number of bytes through md5sum. The result is compared with a line from Debian checksum files like MD5SUMS. Human readable messages and exit value tell the result. In your above example, the script run would look like ./check_debian_iso MD5SUMS CD-1 /dev/cdrom Result on stdout would be either MISMATCH: '/dev/cdrom' checksum differs from 'debian-6.0.3-amd64-CD-1.iso' in 'MD5SUMS' with exit value 3, or Ok: '/dev/cdrom' matches 'debian-6.0.3-amd64-CD-1.iso' in 'MD5SUMS' with exit value 0. For testing, download and rename it: wget http://lists.debian.org/debian-cd/2011/11/bincu5TxtRSZn.bin mv bincu5TxtRSZn.bin check_debian_iso chmod o+x check_debian_iso If you like it, give it a try on as many operating systems as possible, and report your experiences. Helptext: ./check_debian_iso --help Have a nice day :) Thomas -- To UNSUBSCRIBE, email to debian-www-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/98066262030751@192.168.2.69
