Retrieve operational attributes from OpenLDAP

I've been having trouble trying to find some good documentation on how to retrieve operational attributes from OpenLDAP.

I would like to retrieve the base distinguished name of an LDAP server by doing an LDAP search.

How come my search doesn't work when I explicitly ask for namingContexts attribute? I've been told that I need to add a plus ('+') sign to the attribute list.

If this is the case, should I get rid of the "namingContexts" attribute or have both?

ldapsearch -H ldap://ldap.mydomain.com -x -s base -b "" +
# note the + returns operational attributes

Edit: Note how it looks like the attributes requested are empty. Shouldn't the plus sign be in the attribute list? http://www.zytrax.com/books/ldap/ch3/#operational

reference: plus sign operator with OpenLDAP

Solution 1:

How come my search doesn't work when I explicitly ask for namingContexts attribute?

What is not working? Do you recieve an error?

When there is a plus sign it returns all the attributes, regardless if namingContexts is added.

Using:

ldapsearch -x -H ldap://ldap.example.com -s base -b "" namingContexts

Returns:

# extended LDIF
#
# LDAPv3
# base <> with scope baseObject
# filter: (objectclass=*)
# requesting: namingContexts 
#

#
dn:
namingContexts: o=example.com

# search result
search: 2
result: 0 Success

# numResponses: 2
# numEntries: 1

It is also listed using:

ldapsearch -x -H ldap://ldap.example.com -s base -b "" +

Returning:

# extended LDIF
#
# LDAPv3
# base <> with scope baseObject
# filter: (objectclass=*)
# requesting: + 
#

#
dn:
structuralObjectClass: OpenLDAProotDSE
namingContexts: o=example.com
supportedControl: 2.16.840.1.113730.3.4.18
supportedControl: 2.16.840.1.113730.3.4.2
supportedControl: 1.3.6.1.4.1.4203.1.10.1
supportedControl: 1.2.840.113556.1.4.1413
supportedControl: 1.2.840.113556.1.4.1339
supportedControl: 1.2.840.113556.1.4.319
supportedControl: 1.2.826.0.1.334810.2.3
supportedExtension: 1.3.6.1.4.1.1466.20037
supportedExtension: 1.3.6.1.4.1.4203.1.11.1
supportedExtension: 1.3.6.1.4.1.4203.1.11.3
supportedFeatures: 1.3.6.1.4.1.4203.1.5.1
supportedFeatures: 1.3.6.1.4.1.4203.1.5.2
supportedFeatures: 1.3.6.1.4.1.4203.1.5.3
supportedFeatures: 1.3.6.1.4.1.4203.1.5.4
supportedFeatures: 1.3.6.1.4.1.4203.1.5.5
supportedLDAPVersion: 2
supportedLDAPVersion: 3
supportedSASLMechanisms: DIGEST-MD5
supportedSASLMechanisms: CRAM-MD5
subschemaSubentry: cn=Subschema

# search result
search: 2
result: 0 Success

# numResponses: 2
# numEntries: 1

Solution 2:

First access rule in my slapd.conf is explicitly to make sure that this is permitted; make sure you have something similar:

# Let all clients figure out what auth mechanisms are available, determine
# that TLS is okay, etc
access to dn.base=""
        by *            read