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AUTH_SYS Extended Groups changes for NFS authentication for ONTAP 9

Last Updated:

Applies to

  • ONTAP 9
  • UNIX
  • NFS


  • AUTH_SYS provides a UID, GID, and a list of up to 16 supplemental groups to an NFS server
    • By default, these IDs are not validated and are trusted as legitimate
  • To allow for NFS users to belong to more than 16 groups, the option to enable support for Extended Groups introduces ID validation via an appropriate Name Service
  • The validation does the following:
    • Obtain UID from NFS call
    • Preserve gid for SetGID compatibility
    • Query Name Services, such as LDAP, NIS, or the local SVM files regarding the UID and group-membership (this is determined by the ns-switch configuration)
  • If the user has group association local to NFS client, not in name-services, ONTAP cannot grant access based on these unless the user and group are appropriately defined locally on the SVM


  • If the nameservice query produces no results, a credential for that user can not be built, and with no credential within ONTAP's cache, access is denied
  • If there is a limit below 1024 groups when extended auth is set to 1024, check that the  LDAP schema has "Maximum groups supported when RFC 2307bis" enabled
    • The default for this setting is approximately 256, and can stop the Vserver from looking up all the groups in LDAP

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