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HP introduced LDAP support for password authentication in OpenVMS 8.3, which is fantastic. However, when looking for documentation about how it is configured and implemented, one comes up short – there is a dearth of information to be found.

Thanks to Hoffman Labs, this is no longer the case: their article on LDAP exposes the configuration details of ACME LDAP on OpenVMS quite nicely. They have the technical details as well as the README from the ACME LDAP add-on posted there; I’ll try to summarize installation and configuration concisely here.

ACME is the Authentication and Credential Management Extensions, which appear to be an architecture for creating plugins for authentication and so forth, like PAM (the Pluggable Authentication Modules) for UNIX. ACME appears to have been introduced in OpenVMS 8.3.

ACME LDAP is perhaps the most visible of the first of these extensions. This, perhaps, explains its dearth of publically accessible documentation. Currently, ACME LDAP has these features:

  • Support for TLS/SSL
  • Support for StartTLS
  • Support for Active Directory
  • Support for Netscape “expired password” mechanisms

ACME LDAP also has these restrictions:

  • Still requires local username; password only is checked against LDAP
  • Characters in usernames and passwords are restricted to ISO 8859-1 eight bit characters; UTF-8 support not present.
  • Characters in passwords used in Active Directory are restricted to ISO 8859-1 7-bit ASCII characters.

Each user account to be authenticated with LDAP must exist on the system (in the SYSUAF file) and must have the EXTAUTH flag set.

To use ACME LDAP, you must configure the SYS$STARTUP:LDAPACME$CONFIG-STD.INI file. The file can be started by copying the LDAPACME$CONFIG-STD.INI_TEMPLATE file:


An example LDAPACME$CONFIG-STD.INI may look like this:

server = roux.zko.hp.com
port = 636
port_security = ssl
bind_dn = uid=acme-admin,ou=people,dc=acme,dc=mycompany,dc=com
bind_password = swordfish
base_dn = ou=people,dc=acme,dc=mycompany,dc=com
login_attribute = uid
scope = sub
ca_file = sys$manager:acme_ca.crt

This example is suitable for the Red Hat Directory Server (also known as the Fedora Directory Server).

The LDAP Persona extension must also be loaded using the MCR utility:

SYSMAN> exit


Following the load of the LDAP Persona extension, the system must be rebooted:


If there are no errors during startup, then the LDAP Persona extension was loaded correctly.

Change the SYS$MANAGER:ACME$START.COM file to contain a pointer to the initialization file and to start the LDAP extension automatically.

Add the following definition line to ACME$START.COM:


To start the server at ACME load time, add this line:


Finally, configure the system to start the ACME subsystem by adding this line to SYS$MANAGER:SYSTART_VMS.COM:


The description from Hoffman Labs is a perfect example of how community support works!

Update: A nice description (from the VMS Help subsystem) of the ACME server can be found here; it describes SET SERVER ACME_SERVER.