I am trying to encrypt the /tmp partition on a server after it had been configured. I wasn't able to setup up encrypt at install as it wouldn't allow for using a random key. Instead, I created the /tmp-tmp LVM formated as ext and of a size 10G. After I made the changes to the /etc/fstab and /etc/crypttab files, the server started to hang and I've had to use the install disk to boot into maintenance mode to try and resolve the issue.


    enc_t      /dev/mapper/tmp-tmp   /dev/urandom   tmp,cipher=aes-xts-plain64,size=512,hash=sha512


/dev/mapper/enc_t    /tmp   ext4     relatime,async,nosuer,noauto,noatime,nodiratime,nosuid,noexec,nodev,rw        0 0

I have taken a look at the /var/log/messages and dmesg files but didn't see any errors. Can anyone assist with what I did wrong?


I suspect you are running out of entropy as the man page says.

For example: echo -n "pass phrase" > MyPasswordFile For swap encryption /dev/urandom can be used as the password file; using /dev/random may prevent boot completion if the system does not have enough entropy to generate a truly random encryption key.

  • I thought using /dev/urandom prevents the waiting aspect as I've left the server in the hanging state over the weekend to no progress. – user430206 Aug 8 '17 at 20:53

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