Understanding Linux Network Namespaces: How Containers Isolate and Connect Networks

Modern container technologies like Docker and Kubernetes rely heavily on Linux kernel features to provide isolation and security. One of the most fundamental, yet often misunderstood of these features is the network namespace. Network namespaces are what give containers the illusion of having their own network stack: their own interfaces, IP addresses, routing tables, and ARP tables; completely isolated from the host and from other containers. In this article, we’ll break down how network namespaces work, why they are essential for container networking, and how Linux connects isolated namespaces together using virtual Ethernet (veth) interfaces. Through concrete commands and examples, you’ll see how containers are isolated from the host and how they can still communicate with each other when needed. By the end, you’ll have a clear mental model of what happens under the hood when a container gets network access. 1. How does networking work in case of containers Routing and ARP table ins