Using eCryptfs from the Ubuntu Server Guide by OnWorks

6.1. Using eCryptfs

First, install the necessary packages. From a terminal prompt enter:

sudo apt install ecryptfs-utils

Now mount the partition to be encrypted:

sudo mount -t ecryptfs /srv /srv

You will then be prompted for some details on how ecryptfs should encrypt the data.

To test that files placed in /srv are indeed encrypted copy the /etc/default folder to /srv:

sudo cp -r /etc/default /srv

Now unmount /srv, and try to view a file:

sudo umount /srv

cat /srv/default/cron

Remounting /srv using ecryptfs will make the data viewable once again.