document NTP server configuration

_toc.yml

@@ -48,7 +48,7 @@ chapters:
           - file: admin-guide/configuration/xrdp
           - file: admin-guide/configuration/puppet_agent
           - file: admin-guide/configuration/sudo
-          - file: admin-guide/configuration/timeserver
+          - file: admin-guide/configuration/ntp_client
           - file: admin-guide/configuration/keyboard_layout
           - file: admin-guide/configuration/autologin
           - file: admin-guide/configuration/screen_lock
@@ -56,6 +56,7 @@ chapters:
           - file: admin-guide/configuration/alternative_desktops
           - file: admin-guide/configuration/central_logging_elastic
           - file: admin-guide/configuration/metrics_telegraf
+          - file: admin-guide/configuration/ntp_server
           - file: admin-guide/configuration/ssh_host_hopping
           - file: admin-guide/configuration/citrix_vda
           - file: admin-guide/configuration/configuration_email

admin-guide/configuration.md

@@ -35,6 +35,7 @@ Here starts a so far small collections of configuration guides for sysadmins of
 - [Metrics Collection - Configuration Telegraf](configuration/metrics_telegraf)
 
 ## Special Installations
+- [NTP Server](configuration/ntp_server)
 - [SSH Host Hopping as Root (e.g. between cluster members)](configuration/ssh_host_hopping)
 - [Install Citrix VDA](configuration/citrix_vda)
 - [Sending / Relaying Emails](configuration/configuration_email)

admin-guide/configuration/ntp_server.md

@@ -0,0 +1,10 @@
+# NTP Server
+
+Your node can serve as NTP server. To allow access you need to configure which networks/hosts are allowed to contact `chrony` in the Hiera list `ntp_server::allow`:
+
+```
+ntp_server::allow:
+  - '129.129.0.0/16'
+  - '10.10.10.10'
+
+```