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12 people found this helpful
A very good book with a few mistakes
on 7 November 2011
I've over 14 yrs. Linux sys-admin experience and decided to take the exam. So, bought this book to prepare for RHSCA/RHCE exam and found it's very good as study material and also as reference. It seems to be a must-have one for the RHSCA/RHCE candidate, even for a experienced one. However, the included PDF version is bit different form the original book for a few chapters, and there quite a few serious ones. I haven't finished reading the book yet but beware of page 51, 06-ch06.pdf, where it describes how to auto-mount an encrypted LUKS filesystem - if you do that you'll end up with a non-bootable system. After adding the "/etc/fstab" entry (and of course before [re]booting), you need to put this in to the "/etc/crypttab":
< encrypted block device > < path/to/the/actual/device > < password OR none > [list of options]
So, if "/dev/mapper/test-crypt" is the name of the resulting encrypted block device and "/dev/sdb1" is the path to the actual device, the entry should be:
test-crypt /dev/sdb1 none
It'll ask for the LUKS password during boot. For the password less booting, you need to put the password in a file like this:
# touch /root/luks.key && chmod 600 /root/luks.key
# cryptsetup luksAddKey /dev/sdb1 /root/luks.key
# echo "test-crypt /dev/sdb1 /root/luks.key" > /etc/crypttab
(The path and the name of the key file could be anything of your choice but should be matched in every entry).
The "/etc/crypttab" is actually mentioned in the book, page 381, but with some what misleading information. "<directory name w/o slash>" is wrong interpretation, according to the man page.