I want to encrypt a partition with cryptsetup plain mode what i did is here:
cryptsetup create /dev/sdc3
mount /dev/mapper/crypt /crypt
The commands was successfull and asked for the passphrase and everything was done, i copy my data to the /crypt directory and umount the /crypt:
Now how to close the /dev/mapper/crypt device for the security reason that no one can mount it? and how i can open the device again to mount it?