• https://ilearnedhowto.wordpress.com/tag/unshare/
• https://blogs.rdoproject.org/2015/08/hands-on-linux-sandbox-with-namespaces-and-cgroups/
• https://security.stackexchange.com/questions/209529/what-does-enabling-kernel-unprivileged-userns-clone-do
• https://lwn.net/Articles/673597/

sudo su -c 'echo 1 > /proc/sys/kernel/unprivileged_userns_clone'