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Linux Security Technologies

Explore how Linux kernel namespaces enable container isolation within Docker. Understand each namespace type and its role in securing containers, along with Docker’s use of supplementary technologies for enhanced protection.

Kernel namespaces

Kernel namespaces, usually shortened to namespaces, are the main technology for building containers. Let’s quickly compare namespaces and containers with hypervisors and virtual machines (VM).

Namespaces virtualize operating system constructs such as process trees and filesystems, whereas hypervisors virtualize physical resources such as CPUs and disks. In the VM model, hypervisors create virtual machines by grouping virtual CPUs, virtual disks, and virtual network cards so that every VM looks, smells, and feels like a physical machine. In the container model, namespaces create virtual operating systems (containers) by grouping virtual process trees, virtual filesystems, and virtual network interfaces so that every container looks, smells, and feels exactly like a regular OS.

Namespace security and limitations

At a very high level, namespaces ...