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What limitations should I expect if "cryptsetup" is available, but "crypttab" is not?

Related to chapter 10, I noticed that Ubuntu 14.04 has "cryptsetup", but it doesn't have "crypttab". The latter is apparently used to cause the partition passphrase to be requested at boot. What is going to happen if "crypttab" isn't available?


  • coopcoop Posts: 726
    Because you have to create /etc/crypttab if it doesn't exist. Some distros give you a default empty file (red hat does). Others just don't.
  • dkarrdkarr Posts: 40
    Ok, and what would be the significance of "man crypttab" saying "No manual entry for crypttab"?
  • coopcoop Posts: 726
    It means there is no man page for crypttab.

    There is not supposed to be, at least on ubuntu. Perhaps you can do a little research, such as googling, first before posting here. This week I happen to have had time to answer quickly, but that is rarely the case and the other people who monitor tend to drop in every few days or maybe once a week, so unless another student quickly responds (and some do) if you sit around and wait for an answer your progress will be very slow.

    There is an earlier post from Luis


    that explains better. This one does fit in with the scope as it relates to an exercise. But it is not a bug or a showstopper.

  • dkarrdkarr Posts: 40
    I don't "wait around for answers" if I really need an answer to something. I do google searches numerous times a day. My success depends a lot on whether I can find the right question to ask.

    Concerning crypttab again, I note that on my CentOS7.1 box, there IS a crypttab man page, and there is a "/etc/crypttab" file, which is empty. On my Ubuntu 14.04 VM that I'm using for this course, there is neither.

    However, I also note that if I google for "does ubuntu 14.04 use crypttab", I'm led to http://manpages.ubuntu.com/manpages/trusty/man5/crypttab.5.html , which shows the ubuntu 14.04 man page for crypttab. Now I'm wondering, why don't I have a crypttab man page, and what information do you have that says there shouldn't be one?

    Once I figure out exactly what I have to do with /etc/fstab I'll continue stepping through the lab in question.
  • coopcoop Posts: 726
    apt-get install cryptsetup

    You don't have the encryption stuff installed
  • dkarrdkarr Posts: 40
    No, I already did that. It wasn't installed when I started reading this, but I installed it, and I was able to do things with "cryptsetup", including reading the man page. When that was done, however, it didn't install a "crypttab" man page or create an empty file for it.
  • you can still google man crypttab but you may be at a disadvantage if the exam emulation does not have it XD
  • coopcoop Posts: 726
    I do not have specific knowledge about exam questions etc., as we keep a firewall between our training and certification departments. However, I do know that you have network access during the exam so you can do things like yum install package, apt-get, zypper etc. So if you think something is missing you can get it. I also doubt, however, they would ask you to perform a task for which the tools are not on the system already, but in principle they might. Keep in mind that just because some tool does not get installed by our ready-for.sh script (which is constantly being updated) doesn't mean it is not in an exam image or vice versa. Two different groups which is necessary for integrity reasons.
  • dkarrdkarr Posts: 40
    Very odd. As I described earlier, the "cryptsetup" executable is already installed and available. However, I decided to follow these instructions anyway. Curiously, after "apt-get install cryptsetup" finishes (it didn't say anything about "cryptsetup" already being installed), there now exists both a man page for "crypttab", and even a non-empty "/etc/crypttab" file (one commented line).
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