roles/common: minor configuration of Debian 13 SSH

Tweak some of the new OpenSSH per-source penalty settings on Debian
13. For now only adjusting the source network masks and reusing the
list of IPs to exempt from fail2ban.

These being built in makes them easier to use, but I think I will
end up sticking with fail2ban for the heavy lifting because it per-
sists across restarts of the daemon, whereas OpenSSH's doesn't. I
will monitor OpenSSH on Debian 13 to see how to best use it along
side fail2ban.

ansible.cfg

@@ -13,12 +13,6 @@ interpreter_python=auto
 # See: https://docs.ansible.com/ansible/latest/user_guide/connection_details.html#managing-host-key-checking
 host_key_checking = False
 
-ansible_managed = This file is managed by Ansible.%n
-  template: {file}
-  date: %Y-%m-%d %H:%M:%S
-  user: {uid}
-  host: {host}
-
 [privilege_escalation]
 # instead of using -K
 become_ask_pass=True

group_vars/all

@@ -3,4 +3,12 @@
 
 tls_cipher_suite: "ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384"
 
+ansible_managed: |-
+  This file is managed by Ansible.
+
+  {{ 'template: ' + template_path }}
+  {{ 'date: ' + (template_mtime | string) }}
+  {{ 'user: ' + template_uid }}
+  {{ 'host: ' + template_host }}
+
 # vim: set ts=2 sw=2:

roles/caddy/handlers/main.yml

@@ -3,7 +3,7 @@
 
 # I'm currently not sure when we need to restart versus reload
 - name: reload caddy
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     name: caddy
     state: reloaded
 

roles/caddy/templates/etc/caddy/conf.d/vhost.j2

@@ -36,7 +36,7 @@
     {% elif has_wordpress -%}
     root * {{ document_root }}
     encode
-    {%   if ansible_distribution == 'Debian' and ansible_distribution_major_version is version('12', '==') -%}
+    {%   if ansible_distribution_major_version is version('12', '==') -%}
     php_fastcgi unix//run/php/php8.2-fpm-{{ domain_name }}.sock
     {%   endif -%}
     file_server

roles/common/defaults/main.yml

@@ -8,7 +8,7 @@ fail2ban_maxretry: 6
 fail2ban_findtime: 3600
 # 2 weeks in seconds
 fail2ban_bantime: 1209600
-fail2ban_ignoreip: 127.0.0.1/8
+fail2ban_ignoreip: 127.0.0.0/8
 
 # Disable SSH passwords. Must use SSH keys. This is OK because we add the keys
 # before re-configuring the SSH daemon to disable passwords.

roles/common/files/etc/sudoers.d/provisioning

@@ -1 +0,0 @@
-provisioning   ALL=(ALL)  ALL

roles/common/handlers/main.yml

@@ -2,7 +2,7 @@
 # ansible.builtin.file: roles/common/handlers/main.yml
 
 - name: Reload sshd
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     name: "{{ sshd_service_name }}"
     state: reloaded
 
@@ -10,11 +10,11 @@
   ansible.builtin.command: sysctl -p /etc/sysctl.conf
 
 - name: Reload systemd
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     daemon_reload: true
 
 - name: Restart nftables
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     name: nftables
     state: restarted
 
@@ -22,6 +22,6 @@
 # in the order they are defined, not in the order they are listed in the task's
 # notify statement and we must restart fail2ban after updating the firewall.
 - name: Restart fail2ban
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     name: fail2ban
     state: restarted

roles/common/tasks/fail2ban.yml

@@ -1,7 +1,7 @@
 ---
 - name: Install fail2ban
-  when: ansible_distribution_major_version is version('11', '>=')
-  ansible.builtin.package:
+  when: ansible_distribution_version is version('11', '>=')
+  ansible.builtin.apt:
     name:
       - fail2ban
       - python3-systemd
@@ -47,7 +47,7 @@
     - Restart fail2ban
 
 - name: Start and enable fail2ban service
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     name: fail2ban
     state: started
     enabled: true

roles/common/tasks/firewall.yml

@@ -2,14 +2,14 @@
 # Debian 11+ will use nftables directly, with no firewalld.
 
 - name: Install Debian firewall packages
-  when: ansible_distribution_major_version is version('11', '>=')
-  ansible.builtin.package:
+  when: ansible_distribution_version is version('11', '>=')
+  ansible.builtin.apt:
     name: nftables
     state: present
     cache_valid_time: 3600
 
 - name: Remove iptables on newer Debian
-  when: ansible_distribution_major_version is version('11', '>=')
+  when: ansible_distribution_version is version('11', '>=')
   ansible.builtin.apt:
     pkg: iptables
     state: absent
@@ -19,7 +19,7 @@
   ansible.builtin.include_tasks: nftables.yml
 
 - name: Configure fail2ban
-  when: ansible_distribution_major_version is version('9', '>=')
+  when: ansible_distribution_version is version('9', '>=')
   ansible.builtin.include_tasks: fail2ban.yml
 
 # vim: set sw=2 ts=2:

roles/common/tasks/nftables.yml

@@ -75,12 +75,12 @@
 
 # need to reload to pick up service/timer/environment changes
 - name: Reload systemd daemon
-  ansible.builtin.systemd: # noqa no-handler
-    daemon_reload: true
   when: nftables_systemd_units is changed
+  ansible.builtin.systemd_service: # noqa no-handler
+    daemon_reload: true
 
 - name: Start and enable nftables update timers
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     name: "{{ item }}"
     state: started
     enabled: true
@@ -88,7 +88,7 @@
     - update-firehol-nftables.timer
 
 - name: Start and enable nftables
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     name: nftables
     state: started
     enabled: true

roles/common/tasks/ntp.yml

@@ -12,11 +12,9 @@
 
 # Apparently some cloud images don't have this installed by default. From what
 # I can see on existing servers, systemd-timesyncd is a standalone package on
-# Debian 11.
+# Debian 11 and Debian 12.
 - name: Install systemd-timesyncd
-  when:
-    - ansible_distribution == 'Debian'
-    - ansible_distribution_version is version('11', '>='))
+  when: ansible_distribution_version is version('11', '>=')
   ansible.builtin.apt:
     name: systemd-timesyncd
     state: present
@@ -24,13 +22,17 @@
 
 - name: Start and enable systemd's NTP client
   when: ansible_service_mgr == 'systemd'
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     name: systemd-timesyncd
     state: started
     enabled: true
 
-- name: Uninstall ntp on modern Debian
-  when: ansible_service_mgr == 'systemd'
+# On Debian 12 ntp doesn't conflict with systemd-timesyncd so we should try to
+# remove it to be sure.
+- name: Uninstall ntp on Debian 12
+  when:
+    - ansible_service_mgr == 'systemd'
+    - ansible_distribution_major_version is version('12', '==')
   ansible.builtin.apt:
     name: ntp
     state: absent

roles/common/tasks/packages.yml

@@ -48,8 +48,8 @@
         cache_valid_time: 3600
 
     - name: Remove cron-apt
-      ansible.builtin.import_tasks: cron-apt.yml
       tags: cron-apt
+      ansible.builtin.import_tasks: cron-apt.yml
 
     - name: Install tarsnap
       ansible.builtin.import_tasks: tarsnap.yml

roles/common/tasks/sshd.yml

@@ -1,6 +1,7 @@
 ---
-# SSH configs don't change in Debian minor versions
+# Only override the system sshd configuration on older Debian.
 - name: Reconfigure /etc/ssh/sshd_config
+  when: ansible_distribution_version is version('12', '<=')
   ansible.builtin.template:
     src: "sshd_config_{{ ansible_distribution }}-{{ ansible_distribution_major_version }}.j2"
     dest: /etc/ssh/sshd_config
@@ -9,6 +10,18 @@
     mode: "0600"
   notify: Reload sshd
 
+# Newer OpenSSH versions support including extra configuration. The includes
+# happen at the beginning of the file and the first value to be read is used.
+- name: Configure sshd_config.d overrides
+  when: ansible_distribution_version is version('13', '>=')
+  ansible.builtin.template:
+    src: etc/ssh/sshd_config.d/01-{{ ansible_distribution }}-{{ ansible_distribution_major_version }}.conf.j2
+    dest: /etc/ssh/sshd_config.d/01-custom.conf
+    owner: root
+    group: root
+    mode: "0600"
+  notify: Reload sshd
+
 # See: WeakDH (2015): https://weakdh.org/sysadmin.html
 - name: Remove small Diffie-Hellman SSH moduli
   block:

roles/common/tasks/tarsnap.yml

@@ -5,6 +5,7 @@
   register: tarsnap_signing_key_stat
 
 - name: Download tarsnap apt signing key
+  when: not tarsnap_signing_key_stat.stat.exists
   ansible.builtin.get_url:
     url: https://pkg.tarsnap.com/tarsnap-deb-packaging-key.asc
     dest: /etc/apt/keyrings/tarsnap-deb-packaging-key.asc
@@ -12,9 +13,9 @@
     group: root
     mode: "0644"
   register: download_tarsnap_signing_key
-  when: not tarsnap_signing_key_stat.stat.exists
 
 - name: Add tarsnap.org repo
+  when: ansible_architecture != 'armv7l'
   ansible.builtin.template:
     src: tarsnap_sources.list.j2
     dest: /etc/apt/sources.list.d/tarsnap.list
@@ -22,12 +23,11 @@
     group: root
     mode: "0644"
   register: add_tarsnap_apt_repository
-  when: ansible_architecture != 'armv7l'
 
 - name: Update apt cache
+  when: (download_tarsnap_signing_key.status_code is defined and download_tarsnap_signing_key.status_code == 200) or add_tarsnap_apt_repository is changed
   ansible.builtin.apt: # noqa no-handler
     update_cache: true
-  when: (download_tarsnap_signing_key.status_code is defined and download_tarsnap_signing_key.status_code == 200) or add_tarsnap_apt_repository is changed
 
 - name: Install tarsnap
   ansible.builtin.apt:

roles/common/templates/etc/ssh/sshd_config.d/01-Debian-13.conf.j2

@@ -0,0 +1,40 @@
+{{ ansible_managed | comment }}
+
+HostKey /etc/ssh/ssh_host_ed25519_key
+
+# LogLevel VERBOSE logs user's key fingerprint on login. Needed to have a clear
+# audit track of which key was using to log in.
+LogLevel VERBOSE
+
+MaxAuthTries 4
+
+AuthorizedKeysFile	.ssh/authorized_keys
+
+# To disable tunneled clear text passwords, change to no here!
+{% if ssh_password_authentication == 'disabled' %}
+PasswordAuthentication no
+{% else %}
+PasswordAuthentication yes
+{% endif %}
+
+X11Forwarding no
+
+# Based on the ssh-audit profile for Debian 13, but with but with all algos with
+# less than 256 bits removed, as NSA's Suite B removed them years ago and the
+# new (2018) CNSA suite is 256 bits and up.
+#
+# See: ssh-audit.py -P "Hardened Debian 13 (version 1)"
+# See: https://en.wikipedia.org/wiki/Commercial_National_Security_Algorithm_Suite
+Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes256-ctr
+MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com
+KexAlgorithms mlkem768x25519-sha256,sntrup761x25519-sha512,sntrup761x25519-sha512@openssh.com
+
+{% if ssh_allowed_users is defined and ssh_allowed_users %}
+AllowUsers {{ ssh_allowed_users|join(" ") }} {{ provisioning_user.name }}
+{% endif %}
+
+PerSourcePenaltyExemptList {{ fail2ban_ignoreip | replace(" ", ",") }}
+
+# Mask to use for IPv4 and IPv6 respectively when applying network penalties.
+# The default is 32:128.
+PerSourceNetBlockSize 24:56

roles/common/templates/etc/systemd/system/fail2ban.service.d/override.conf.j2

@@ -6,14 +6,14 @@ PartOf=nftables.service
 PrivateDevices=yes
 PrivateTmp=yes
 ProtectHome=read-only
-{% if ansible_distribution == 'Debian' and ansible_distribution_major_version is version('11','>=') %}
+{% if ansible_distribution_version is version('11','>=') %}
 ProtectSystem=strict
 {% else %}
 {# Older systemd versions don't have ProtectSystem=strict #}
 ProtectSystem=full
 {% endif %}
 NoNewPrivileges=yes
-{% if ansible_distribution == 'Debian' and ansible_distribution_major_version is version('11','>=') %}
+{% if ansible_distribution_version is version('11','>=') %}
 ReadWritePaths=-/var/run/fail2ban
 ReadWritePaths=-/var/lib/fail2ban
 ReadWritePaths=-/var/log/fail2ban.log

roles/mariadb/handlers/main.yml

@@ -1,6 +1,6 @@
 ---
 - name: restart mariadb
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     name: mariadb
     state: restarted
 

roles/munin/handlers/main.yml

@@ -1,4 +1,4 @@
 ---
 # ansible.builtin.file: roles/munin/handlers/main.yml
 - name: restart munin-node
-  ansible.builtin.systemd: name=munin-node state=restarted
+  ansible.builtin.systemd_service: name=munin-node state=restarted

roles/munin/tasks/munin-node.yml

@@ -26,7 +26,7 @@
     - restart munin-node
 
 - name: Start munin-node
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     name: munin-node
     state: started
     enabled: true

roles/nginx/handlers/main.yml

@@ -1,6 +1,6 @@
 ---
 - name: Reload nginx
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     name: nginx
     state: reloaded
 

roles/nginx/tasks/letsencrypt.yml

@@ -82,7 +82,7 @@
 
     # always issues daemon-reload just in case the service/timer changed
     - name: Start and enable systemd timer to renew Let's Encrypt certs
-      ansible.builtin.systemd:
+      ansible.builtin.systemd_service:
         name: renew-letsencrypt.timer
         state: started
         enabled: true

roles/nginx/tasks/main.yml

@@ -119,7 +119,7 @@
   tags: nginx
 
 - name: Start and enable nginx service
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     name: nginx
     state: started
     enabled: true

roles/nginx/templates/vhost.conf.j2

@@ -77,7 +77,7 @@ server {
         # See: https://httpoxy.org/
         fastcgi_param HTTP_PROXY "";
 
-        {% if ansible_distribution == 'Debian' and ansible_distribution_major_version is version('12', '==') %}
+        {% if ansible_distribution_major_version is version('12', '==') %}
         fastcgi_pass unix:/run/php/php8.2-fpm-{{ domain_name }}.sock;
         {% endif %}
         fastcgi_index index.php;

roles/php_fpm/handlers/main.yml

@@ -1,7 +1,7 @@
 ---
 # For Debian 12
 - name: Reload php8.2-fpm
-  ansible.builtin.systemd:
+  ansible.builtin.systemd_service:
     name: php8.2-fpm
     state: reloaded