Hardening Docker Daemon Configuration

Overview

The Docker daemon (dockerd) runs with root privileges and controls all container operations. Hardening its configuration through /etc/docker/daemon.json, TLS certificates, user namespace remapping, and network restrictions is essential to prevent privilege escalation, lateral movement, and container breakout attacks.

When to Use

• When deploying or configuring hardening docker daemon configuration capabilities in your environment
• When establishing security controls aligned to compliance requirements
• When building or improving security architecture for this domain
• When conducting security assessments that require this implementation

Prerequisites

• Docker Engine 24.0+ installed
• Root or sudo access to the Docker host
• OpenSSL for TLS certificate generation
• Understanding of Linux namespaces and cgroups

Core Hardened daemon.json

{
  "icc": false,
  "userns-remap": "default",
  "no-new-privileges": true,
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "10m",
    "max-file": "5"
  },
  "storage-driver": "overlay2",
  "live-restore": true,
  "userland-proxy": false,
  "default-ulimits…