Disable dnsmasq Service

Cette page n'est pas encore disponible en français, sa traduction est en cours.
Si vous avez des questions ou des retours sur notre projet de traduction actuel, n'hésitez pas à nous contacter.

Description

The dnsmasq service can be disabled with the following command:

$ sudo systemctl mask --now dnsmasq.service

Rationale

Unless a system is specifically designated to act as a DNS caching, DNS forwarding and/or DHCP server, it is recommended that the package be removed to reduce the potential attack surface.

Remediation

Shell script

The following script can be run on the host to remediate the issue.

#!/bin/bash

# Remediation is applicable only in certain platforms
if dpkg-query --show --showformat='${db:Status-Status}' 'linux-base' 2>/dev/null | grep -q '^installed$'; then

SYSTEMCTL_EXEC='/usr/bin/systemctl'
if [[ $("$SYSTEMCTL_EXEC" is-system-running) != "offline" ]]; then
  "$SYSTEMCTL_EXEC" stop 'dnsmasq.service'
fi
"$SYSTEMCTL_EXEC" disable 'dnsmasq.service'
"$SYSTEMCTL_EXEC" mask 'dnsmasq.service'
# Disable socket activation if we have a unit file for it
if "$SYSTEMCTL_EXEC" -q list-unit-files dnsmasq.socket; then
    if [[ $("$SYSTEMCTL_EXEC" is-system-running) != "offline" ]]; then
      "$SYSTEMCTL_EXEC" stop 'dnsmasq.socket'
    fi
    "$SYSTEMCTL_EXEC" mask 'dnsmasq.socket'
fi
# The service may not be running because it has been started and failed,
# so let's reset the state so OVAL checks pass.
# Service should be 'inactive', not 'failed' after reboot though.
"$SYSTEMCTL_EXEC" reset-failed 'dnsmasq.service' || true

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Ansible playbook

The following playbook can be run with Ansible to remediate the issue.

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_dnsmasq_disabled

- name: Disable dnsmasq Service - Collect systemd Services Present in the System
  ansible.builtin.command: systemctl -q list-unit-files --type service
  register: service_exists
  changed_when: false
  failed_when: service_exists.rc not in [0, 1]
  check_mode: false
  when: '"linux-base" in ansible_facts.packages'
  tags:
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_dnsmasq_disabled

- name: Disable dnsmasq Service - Ensure dnsmasq.service is Masked
  ansible.builtin.systemd:
    name: dnsmasq.service
    state: stopped
    enabled: false
    masked: true
  when:
  - '"linux-base" in ansible_facts.packages'
  - service_exists.stdout_lines is search("dnsmasq.service", multiline=True)
  tags:
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_dnsmasq_disabled

- name: Unit Socket Exists - dnsmasq.socket
  ansible.builtin.command: systemctl -q list-unit-files dnsmasq.socket
  register: socket_file_exists
  changed_when: false
  failed_when: socket_file_exists.rc not in [0, 1]
  check_mode: false
  when: '"linux-base" in ansible_facts.packages'
  tags:
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_dnsmasq_disabled

- name: Disable dnsmasq Service - Disable Socket dnsmasq
  ansible.builtin.systemd:
    name: dnsmasq.socket
    enabled: false
    state: stopped
    masked: true
  when:
  - '"linux-base" in ansible_facts.packages'
  - socket_file_exists.stdout_lines is search("dnsmasq.socket", multiline=True)
  tags:
  - disable_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - service_dnsmasq_disabled