diff --git a/group_vars/debian b/group_vars/debian
index 1fb41f6..bc7ba4f 100644
--- a/group_vars/debian
+++ b/group_vars/debian
@@ -1,2 +1,13 @@
 ---
 ansible_python_interpreter: /usr/bin/python3.7
+
+dns: 213.133.98.98 8.8.8.8
+ipv6_subnet: '2a01:4f8:150:926f::'
+ipv4_subnet: 10.0.0.0
+
+ipv6: '{{ ipv6_subnet | ipmath(2 * (vm_index +2)+1) }}/127'
+ipv6route: '{{ ipv6_subnet | ipmath(2 * (vm_index +2)) }}'
+
+ansible_ssh_host: '{{ ipv4_subnet | ipmath(2 * vm_index +1) }}'
+ipv4: '{{ ipv4_subnet | ipmath(2 * vm_index +1) }}/31'
+ipv4route: '{{ ipv4_subnet | ipmath(2 * vm_index) }}'
diff --git a/host_vars/cloud.emma.ccchb.de.yml b/host_vars/cloud.emma.ccchb.de.yml
index fcef44b..7346f73 100644
--- a/host_vars/cloud.emma.ccchb.de.yml
+++ b/host_vars/cloud.emma.ccchb.de.yml
@@ -1,8 +1,5 @@
-ipv6: 2a01:4f8:150:926f::5/127
-ipv6route: 2a01:4f8:150:926f::4
-ipv4: 10.0.0.1/31
-ipv4route: 10.0.0.0
-dns: 213.133.98.98 8.8.8.8
+vm_index: 0
+
 nginx_acme_mail: "webmaster@ccchb.de"
 nextcloud_domain: "cloud.ccchb.de"
 php_config:
diff --git a/host_vars/dn42.emma.ccchb.de.yml b/host_vars/dn42.emma.ccchb.de.yml
index d4cb802..9f4c5c6 100644
--- a/host_vars/dn42.emma.ccchb.de.yml
+++ b/host_vars/dn42.emma.ccchb.de.yml
@@ -1,10 +1,4 @@
-ansible_ssh_host: 10.0.0.3
-
-ipv6: 2a01:4f8:150:926f::7/127
-ipv6route: 2a01:4f8:150:926f::6
-ipv4: 10.0.0.3/31
-ipv4route: 10.0.0.2
-dns: 213.133.98.98 8.8.8.8
+vm_index: 1
 
 user_mgmt:
   crest: