diff --git a/mikrotikbackup_clean.yml b/mikrotikbackup_clean.yml
index 92ce03c..dd90e9a 100644
--- a/mikrotikbackup_clean.yml
+++ b/mikrotikbackup_clean.yml
@@ -1,9 +1,13 @@
+---
 - name: Backup and/or Upgrade MikroTik
   hosts: mikrotik_routers
   gather_facts: no
+  serial: 10
 
   vars:
     backup_dir: /opt/mikrotik_backups/
+    checkmk_url: "http://checkmk-server/mysite/check_mk/api/1.0/domain-types/service/collections/all"
+    checkmk_service_description: "MikroTik Backup/Upgrade"
 
   tasks:
 
@@ -17,7 +21,7 @@
       tags: always
 
     - name: Parse router name
-      set_fact:
+      ansible.builtin.set_fact:
         router_name: "{{ identity_raw.stdout[0].split(': ')[1] | trim }}"
       tags: always
 
@@ -25,10 +29,11 @@
       ansible.builtin.command: date +%Y-%m-%d_%H-%M-%S
       register: date_out
       delegate_to: localhost
+      changed_when: false
       tags: always
 
     - name: Set timestamp fact
-      set_fact:
+      ansible.builtin.set_fact:
         ts: "{{ date_out.stdout }}"
       tags: always
 
@@ -53,9 +58,16 @@
       ansible.builtin.copy:
         content: "{{ export_cfg.stdout[0] }}"
         dest: "{{ backup_dir }}/{{ router_name }}-{{ ts }}.rsc"
+        mode: "0600"
       delegate_to: localhost
       tags: backup
 
+    - name: Mark backup success
+      ansible.builtin.set_fact:
+        backup_ok: true
+        backup_file: "{{ backup_dir }}/{{ router_name }}-{{ ts }}.rsc"
+      tags: backup
+
     # ----------------------------
     # Upgrade (tag: upgrade)
     # ----------------------------
@@ -66,43 +78,145 @@
       tags: upgrade
 
     - name: Parse installed and latest versions
-      set_fact:
-        installed_version: "{{ update_check.stdout[0] | regex_search('installed-version: ([\\d.]+)', '\\1') | first }}"
-        latest_version: "{{ update_check.stdout[0] | regex_search('latest-version: ([\\d.]+)', '\\1') | first }}"
+      ansible.builtin.set_fact:
+        installed_version: >-
+          {{
+            (
+              update_check.stdout[0]
+              | regex_search('installed-version: ([^\\s]+)', '\\1')
+              | default([])
+            ) | first | default('unknown')
+          }}
+        latest_version: >-
+          {{
+            (
+              update_check.stdout[0]
+              | regex_search('latest-version: ([^\\s]+)', '\\1')
+              | default([])
+            ) | first | default('unknown')
+          }}
+      tags: upgrade
+
+    - name: Set upgrade-needed fact
+      ansible.builtin.set_fact:
+        upgrade_needed: >-
+          {{
+            installed_version != 'unknown'
+            and latest_version != 'unknown'
+            and installed_version != latest_version
+          }}
       tags: upgrade
 
     - name: Skip upgrade if already on latest
       ansible.builtin.debug:
         msg: "Router {{ router_name }} is already on latest version {{ installed_version }}. Skipping upgrade."
-      when: installed_version == latest_version
+      when: not upgrade_needed
       tags: upgrade
 
     - name: Trigger package download and install
       community.routeros.command:
         commands: /system package update install
       register: upgrade_result
-      when: installed_version != latest_version
+      when: upgrade_needed
       tags: upgrade
 
     - name: Wait for router to come back online after reboot
       ansible.builtin.wait_for_connection:
         delay: 180
-        timeout: 300
+        timeout: 600
         sleep: 10
       when:
-        - installed_version != latest_version
-        - upgrade_result is not failed
+        - upgrade_needed
+        - upgrade_result is succeeded
       tags: upgrade
 
     - name: Confirm upgraded version
       community.routeros.command:
         commands: /system resource print
       register: post_upgrade_info
-      when: installed_version != latest_version
+      when: upgrade_needed
+      tags: upgrade
+
+    - name: Parse post-upgrade version
+      ansible.builtin.set_fact:
+        post_upgrade_version: >-
+          {{
+            (
+              post_upgrade_info.stdout[0]
+              | regex_search('version: ([^\\s]+)', '\\1')
+              | default([])
+            ) | first | default('unknown')
+          }}
+      when: upgrade_needed
       tags: upgrade
 
     - name: Show post-upgrade RouterOS version
       ansible.builtin.debug:
-        msg: "{{ post_upgrade_info.stdout[0] | regex_search('version: .+') }}"
-      when: installed_version != latest_version
-      tags: upgrade
\ No newline at end of file
+        msg: "Router {{ router_name }} upgraded to version {{ post_upgrade_version }}"
+      when: upgrade_needed
+      tags: upgrade
+
+    # ----------------------------
+    # Build Checkmk status
+    # ----------------------------
+    - name: Build Checkmk result when no upgrade was needed
+      ansible.builtin.set_fact:
+        cmk_state: 0
+        cmk_output: >-
+          OK - router={{ router_name }}
+          backup=ok
+          installed={{ installed_version }}
+          latest={{ latest_version }}
+          upgrade_needed=no
+          backup_file={{ backup_file | default('n/a') }}
+          backup_ts={{ ts }}
+      when: not upgrade_needed
+      tags: always
+
+    - name: Build Checkmk result when upgrade succeeded
+      ansible.builtin.set_fact:
+        cmk_state: "{{ 0 if post_upgrade_version == latest_version else 2 }}"
+        cmk_output: >-
+          {{ 'OK' if post_upgrade_version == latest_version else 'CRIT' }} -
+          router={{ router_name }}
+          backup=ok
+          installed_before={{ installed_version }}
+          latest={{ latest_version }}
+          upgrade_needed=yes
+          upgraded_to={{ post_upgrade_version }}
+          backup_file={{ backup_file | default('n/a') }}
+          backup_ts={{ ts }}
+      when: upgrade_needed
+      tags: always
+
+    # ----------------------------
+    # Push result to Checkmk
+    # ----------------------------
+    - name: Send result to Checkmk
+      delegate_to: localhost
+      ansible.builtin.uri:
+        url: "{{ checkmk_url }}"
+        method: POST
+        headers:
+          Authorization: "Bearer {{ lookup('env', 'CHECKMK_TOKEN') }}"
+          Accept: "application/json"
+          Content-Type: "application/json"
+        body_format: json
+        body:
+          host_name: "{{ router_name }}"
+          service_description: "{{ checkmk_service_description }}"
+          state: "{{ cmk_state | int }}"
+          output: "{{ cmk_output }}"
+        return_content: true
+        status_code:
+          - 200
+          - 201
+          - 204
+      register: checkmk_result
+      failed_when: false
+      tags: always
+
+    - name: Show Checkmk response
+      ansible.builtin.debug:
+        var: checkmk_result
+      tags: always
\ No newline at end of file