cis-docker-v170-2-4

name	cis-docker-v170-2.4
description	Ensure Docker is allowed to make changes to iptables
category	cis-docker
version	1.7.0
author	cyberstrike-official
tags	["cis","docker","daemon","configuration","iptables","firewall","network"]
cis_id	2.4
cis_benchmark	CIS Docker Benchmark v1.7.0
tech_stack	["docker"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

CIS Docker Benchmark v1.7.0 - Control 2.4

Profile Applicability

• Level: 1 - Docker - Linux

Description

The iptables firewall is used to set up, maintain, and inspect the tables of IP packet filter rules within the Linux kernel. The Docker daemon should be allowed to make changes to the iptables ruleset.

Rationale

Docker will never make changes to your system iptables rules unless you allow it to do so. If you do allow this, Docker server can automatically make any required changes. We recommended letting Docker make changes to iptables automatically in order to avoid networking misconfigurations that could affect the communication between containers and with the outside world. Additionally, this reduces the administrative overhead of updating iptables every time you add containers or modify networking options.

Impact

The Docker daemon service requires iptables rules to be enabled before it starts. Any restarts of iptables during Docker daemon operation may result in losing Docker created rules. Adding iptables-persistent to your iptables install can assist with mitigation of this impact.

Audit Procedure

To confirm this setting you should review the dockerd start-up options and the settings in /etc/docker/daemon.json.

To review the dockerd startup options, use:

ps -ef | grep dockerd

Ensure that the --iptables parameter is either not present or not set to false.

The contents of /etc/docker/daemon.json should also be reviewed for this setting.

Remediation

Do not run the Docker daemon with --iptables=false parameter. For example, do not start the Docker daemon as below:

dockerd --iptables=false

Default Value

By default, iptables is set to true.

References

1. https://docs.docker.com/engine/reference/commandline/dockerd/
2. https://docs.docker.com/network/iptables/

CIS Controls

Controls Version	Control	IG 1