debian.ansible.basics/hardening.yml

---
- name: Basic Debian Linux Hardening
  hosts: all
  tasks:

    - name: check if we are in an container env by existing systemd
      stat:
        path: /usr/bin/systemd
      register: nocontainer

#    - name: Remove root-Password
#      user:
#        name: root
#        password: '*'
#      when: nocontainer.stat.exists == true

    - name: SSHD hardening
      blockinfile:
        path: /etc/ssh/sshd_config.d/hardening.conf
        mode: "0444"
        owner: root
        group: root
        create: yes
        insertbefore: BOF # Beginning of the file
        marker: "# {mark} ANSIBLE MANAGED BLOCK"
        block: |
          Port 22
          Port 33
          PermitRootLogin prohibit-password
          PermitUserRC no
          PermitUserEnvironment no
          PubkeyAuthentication yes
          X11Forwarding no
          AllowAgentForwarding no
          AllowTcpForwarding yes
          Subsystem sftp internal-sftp -f AUTH -l INFO -u 0007
          ## Ciphers Check https://sshcheck.com/server/{{inventory_hostname}}/
          # nmap -p22 -n -sV --script ssh2-enum-algos localhost
          KexAlgorithms curve25519-sha256@libssh.org
          HostKeyAlgorithms ssh-ed25519
          Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com
          MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,umac-128-etm@openssh.com
          IgnoreRhosts yes
          LogLevel VERBOSE
          AddressFamily any
        backup: yes
        validate: /usr/sbin/sshd -T -f %s
      notify:
      - Restart sshd
      when: nocontainer.stat.exists == true

    - name: Disable external sftp-Subsystem
      replace:
        path: /etc/ssh/sshd_config
        regexp: '(^Subsystem.*sftp.*)'
        replace: '#\1'
        validate: /usr/sbin/sshd -T -f %s
        backup: yes
      notify:
      - Restart sshd
      when: nocontainer.stat.exists == true


  handlers:

    - name: Restart sshd
      service:
        name: ssh
        state: restarted