EvilZone
Hacking and Security => Tutorials => : proxx November 17, 2014, 05:30:01 PM
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Hello Evilzone.
Just some quick stuff on dd.
I recently did a lot with dd because I had to make a shitton of clones.
Simple image of an entire drive:
dd if=/dev/sda > myimage.img
Simple restore of an entire drive:
cat myimage.img | dd of=/dev/sdaRidiculously easy and it just works.
We can improve this a bit by using some compression since it will drop an image the same size as the disk even if there is no data present, thats a lot of wasted space.
And the fact ofcourse that there is less data to write with a CPU cycle tradeoff.
Let do the same thing with gzip:
dd if=/dev/sda | gzip -c > myimage.imgAnd a restore:
gunzip -c myimage.img | dd of=/dev/sda
Direct disk to disk copy:
dd if=dev/sda of=/dev/sdb
I left out stuff about blocksizes to keep the examples clear.
For normal old fashioned HDD's you can just use a blocksize of 512 bytes.
The newer generation of HDD's with a blocksize of 4k (emulated or true) can use a BS of 4096, should not be used otherwise.
In some cases reads can be improved when a higher bs is used.
I wont go too deep into this for now, maybe add more later.
More stuff on blocksizes: http://en.wikipedia.org/wiki/Dd_%28Unix%29
I will append to this later since I thought I had more time to write this.
Main focus is the mere simplicity.
And remember kids, DD can ruin your day :)
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Simple restore of an entire drive:
cat myimage.img | of=/dev/sda
You forgot "dd" there.
cat myimage.img | dd of=/dev/sda
And I like the idea of compressing the data stream on the fly, never thought of that.. +1