Tuesday, March 25, 2008
Monday, March 24, 2008
How do you create your images? Do you want to have a BIG file or a SMALL file
qemu-img create debian.img 5G
this creates a large file
which is SPARSE thus is capable of being compressed
tar -cjSf debian.tar.bz2 debian.img
which can be moved.
On the other hand you can make a qcow small file to begin with.
qemu-img create debian.img -f qcow 5G
this is a small file.
And can make a copy file to use.
qemu-img create -b debian.img -f qcow stable.ovl
this second is a very tiny copy file, just stores the diffs.
Sunday, March 23, 2008
Here is some nice stuff.
I have a Windows XP SP2 installation that I use for work, while my current personal OS of choice is Windows Vista. I only work weekends, so rebooting wasn’t too bothersome initially. Over time it has become more and more of a chore, as I can’t easily switch from one development environment to another without rebooting. I decided it was time to make my work installation a virtual machine.
I had some additional complications that made the process a little non-standard. I originally tried using VMWare’s converter tool, but it would fail at 97% of the creation of the disk. I then tried using a Windows port of the Unix utility ‘dd’ to create a raw image of the disk, but because the Windows volume manager was accessing the disk, dd would give me access errors. Additionally, the VMWare converter doesn’t support converting from a raw image (…grr…), so Qemu’s qemu-img tool would have to be used to convert the raw image to a disk in VMWare’s vmdk format.
The steps to reach our goal aren’t too complicated, and can be replicated by others easily. To do it, I used:
- VMWare Workstation
- A Linux installation or LiveCD (I used my existing Debian installation, but something like Knoppix would work fine)
- NTFS-3G (if you plan on writing out to an NTFS partition from Linux, as I did)
I started by booting into my Linux install. Linux only mounts the disks it uses (hint hint, Microsoft) so we can access all sectors of the partition to make a dump of the disk with dd. I first had to mount the partition where I wanted the output file to reside, which uses NTFS:
ntfs-3g /dev/sdb1 /mnt/external
Next, create the image. I did this with the following (substitute your device/partition and output file):
dd if=/dev/hdc3 of=/mnt/external/diskImage/XPSP2.img bs=1024
When that finishes, the file specified with the ‘of’ option in dd will contain a block-by-block exact copy of your partition. However, it is in a raw format - we need it in a format VMWare can read. This is where Qemu comes in. Qemu is distributed with qemu-img, a tool used for creating, manipulating, and converting images. Specifically, our goal is to use qemu-img’s convert functionality to convert from a raw image format to the vmdk format. This is accomplished with:
qemu-img convert -f raw /mnt/external/diskImage/XPSP2.img -O vmdk /mnt/external/diskImage/XPSP2.vmdk
Be prepared to wait. For a 40gb image, this process took roughly 12 hours. Since qemu-img provides no status as to how far it has come, I kept tabs on it just by monitoring the filesize of the output image. This is entirely unnecessary, but if you want to do the same, just open a new terminal and type the following:
while [1 -gt 0 ]; do du -hs /mnt/external/diskImage/XPSP2.vmdk; sleep 10; clear; done
This will just print out the size of the file on your screen so you can watch it grow.
When the process is completed, boot back into Windows (or if you are using Linux as the host, stay put) and create a virtual machine around your new disk image. Don’t forget to remove the original img created with dd, it is a huge waste of disk space :)
- This process is really only feasible if you have a lot of disk space. At worst, the disk requirements are greater than 2*P, where P is the partition size of the virtual machine you wish to create. However, qemu-img only writes out actual data, not empty sectors, so your output image will be the size of the used space in the input image. For my conversion, I used over 40gb (input)+15gb (output) of disk space, which was reclaimed with the deletion of the output of dd, and resizing another partition to use the old physical installation’s space.
- qemu-img doesn’t support stream input, which is why we can’t pipe dd’s output directly into qemu-img convert. This would have reduced the disk requirements to only the size of the vmdk image, and sped up the process substantially. Bug the Qemu developers to implement this feature :)
then a comment said
In my last post I chronicled the time consuming process of converting an image produced using the Unix dd utility to a vmware VMDK virtual disk. The process does work, but VMWare will only load it if the image contains a master boot record that still contains the appropriate information when removed from the rest of the system. Additionally, I think it is appropriate to mention again how terribly slow it is. We can circumvent these problems with Live View for Windows, a program developed for forensic work by Carnegie Mellon University.
The process for creating the image with dd is the same as last time, IE, by doing something along the lines of:
dd if=/dev/hdc3 of=/mnt/external/diskImage/XPSP2.img bs=1024
Once that image is generated and you are back in Windows, simply launch the Live View utility and… the rest is pretty self explanatory. Once the dd image is generated, the Live View program takes only a couple minutes to create the new vmdk, configure the virtual machine, and launch it. Sweet, sweet efficiency!
Live View 0.6 is now available for download.
This version adds support for third party image formats such as EnCase with the use of image mounting software such as Mount Image Pro or Physical Disk Emulator. This release also adds support for the newest versions of Java and VMware, improves the boot preparation process to allow a wider variety of system configurations to boot successfully, and fixes a number of bugs. For more information, see the changelog.
We appreciate the feedback and encourage you to continue to report bugs and make suggestions to help make this tool more useful for everyone. The best way to do this is to post to the forums.
Live View is a Java-based graphical forensics tool that creates a VMware virtual machine out of a raw (dd-style) disk image or physical disk. This allows the forensic examiner to "boot up" the image or disk and gain an interactive, user-level perspective of the environment, all without modifying the underlying image or disk. Because all changes made to the disk are written to a separate file, the examiner can instantly revert all of his or her changes back to the original pristine state of the disk. The end result is that one need not create extra "throw away" copies of the disk or image to create the virtual machine.
Live View is capable of booting
- Full disk raw images
- Bootable partition raw images
- Physical Disks (attached via a USB or Firewire bridge)
- Specialized and closed image formats (using 3rd party image mounting software)
Containing the following operating systems
- Windows 2003, XP, 2000, NT, Me, 98
- Linux (limited support)
Behind the scenes, Live View automates a wide array of technical tasks. Some of these include: resolving hardware conflicts resulting from booting on hardware other than that on which the OS was originally installed; creating a customized MBR for partition-only images; and correctly specifying a virtual disk to match the original image or physical disk.
which is amazing because boot failure due to changing underlying hardware machines is the main issue i have often with windows. you can't just plug a machine into a different machine! now you can
i have not gotten this working myself.
my machine just reboots over and over again.