  Over the last few years, the use of virtualization technologies has increased
dramatically. This makes the demand for efficient and secure virtualization
solutions become more obvious. Container-based virtualization and
hypervisor-based virtualization are two main types of virtualization
technologies that have emerged to the market. Of these two classes,
container-based virtualization is able to provide a more lightweight and
efficient virtual environment, but not without security concerns. In this
paper, we analyze the security level of Docker, a well-known representative of
container-based approaches. The analysis considers two areas: (1) the internal
security of Docker, and (2) how Docker interacts with the security features of
the Linux kernel, such as SELinux and AppArmor, in order to harden the host
system. Furthermore, the paper also discusses and identifies what could be done
when using Docker to increase its level of security.
