add guide for nfs4 acl configuration

_toc.yml

@@ -134,6 +134,7 @@ chapters:
               - file: admin-guide/configuration/monitoring/journal_remote
               - file: admin-guide/configuration/monitoring/syslog_forwarding
               - file: admin-guide/configuration/monitoring/central_logging_elastic
+          - file: admin-guide/configuration/nfs4_acls
 
       - file: admin-guide/custom_repositories
       - file: admin-guide/troubleshooting

admin-guide/configuration/nfs4_acls.md

@@ -0,0 +1,33 @@
+# NFS4 ACLs 
+
+**IMPORTANT: NFS4 ACLs are only respected if the mount ist using sec=krb5 or higher!**
+
+Prerequisite: NFS4 ACL support needs to be enabled on the NFS server / Netapp SVM
+(existing mounts need to be re-mounted after the support is enabled!)
+
+Install necessary tools:
+```bash
+dnf install nfs4-acl-tools
+```
+
+Get current ACLs of a share/directory:
+```bash
+nfs4_getfacl /mnt/nfs_share
+```
+
+
+Set an ACL
+(acls are best set on a system that has norootsquash and sec=sys access)
+```bash
+# group: 35593
+nfs4_setfacl -a A:dfg:35593:RWX /modules/test
+```
+Executing the command above twice will result in 2 identical entryies in the directories ACL. 
+*To avoid this the complete ACL one could be set at once with the `-s` option.*
+
+
+While listing the files with `ls` the trailing `+` at the end of he permissions indicate that some acls apply to this file/directory
+```bash
+[~]# ls -la /test/
+-rw-r--r--+ 1 root root          6 Jul 16 15:41 test.me
+```