When working with OpenLDAP (version 2.4.18 on Ubuntu 9.10), the root DSE (DSA-Specific Entry) serves as a critical entry point that provides server information. The command:
ldapsearch -x -W -D 'cn=manager,dc=example,dc=org' \
-b '' -s base '(objectclass=*)' +
should return metadata about the LDAP server, but in this case, it only shows a success message without actual data. This indicates either a configuration or access control issue.
The current Access Control Lists (ACLs) show:
olcAccess: to attrs=userPassword,shadowLastChange
by self write
by anonymous auth
by dn.base="cn=manager,dc=example,dc=org" write
by * none
olcAccess: to dn.base=""
by * read
olcAccess: to *
by self write
by dn.base="cn=manager,dc=example,dc=org" write
by * read
While this configuration appears correct at first glance (with explicit read access to the root DSE), there might be underlying issues with the database backend or schema.
First, check if the database is properly initialized by examining the slapd configuration:
sudo ldapsearch -Q -LLL -Y EXTERNAL -H ldapi:/// -b cn=config dn
Look for the database definition that should include something like:
dn: olcDatabase={1}hdb,cn=config
1. Explicitly enable root DSE access in the database configuration:
dn: olcDatabase={-1}frontend,cn=config
changetype: modify
add: olcAccess
olcAccess: to dn.base="" by * read
2. Check for schema issues that might prevent the root DSE from being displayed:
ldapsearch -x -b cn=schema,cn=config -LLL dn
3. Verify the database is properly mounted by checking the backend status:
sudo slapcat -b cn=config | grep olcDatabase
Temporarily increase the log level to see what's happening during the search operation:
sudo ldapmodify -Y EXTERNAL -H ldapi:/// <Then check the logs after running your search:
tail -f /var/log/syslog | grep slapd
Try accessing the root DSE without authentication to isolate the issue:
ldapsearch -x -b '' -s base '(objectclass=*)' +
If this works, the problem is likely in your ACLs or bind credentials.
Ensure your database has proper root access configuration by verifying:
sudo ldapsearch -Y EXTERNAL -H ldapi:/// -b cn=config \
"(olcDatabase=*)" olcAccess
The output should show read access to the root DSE similar to:
olcAccess: {0}to dn.base="" by * read
The root DSE (DSA-Specific Entry) is a special LDAP entry that provides server-specific information. When your ldapsearch query returns empty results despite proper ACL configuration, we need to examine multiple layers:
# Diagnostic command to check basic connectivity
ldapwhoami -x -H ldap://localhost -D "cn=manager,dc=example,dc=org" -W
First verify these essential components in your slapd.conf or dynamic config (cn=config):
# Check if root DSE access is properly enabled
ldapsearch -Y EXTERNAL -H ldapi:/// -b cn=config '(olcAccess=*)'
Your current ACL setup appears correct at first glance, but let's enhance it for better reliability:
# Recommended ACL modifications for root DSE
olcAccess: to dn.base="" by * read
olcAccess: to dn.base="cn=Subschema" by * read
olcAccess: to attrs=userPassword,shadowLastChange
by self write
by anonymous auth
by dn.base="cn=admin,dc=example,dc=org" write
by * none
olcAccess: to *
by self write
by dn.base="cn=admin,dc=example,dc=org" write
by * read
Enable verbose logging to identify potential issues:
# Add to slapd configuration
olcLogLevel: stats
Then monitor logs with:
tail -f /var/log/syslog | grep slapd
Try these specialized queries to isolate the problem:
# Check with anonymous bind
ldapsearch -x -b "" -s base "(objectclass=*)" "*" +
# Check schema awareness
ldapsearch -x -b "cn=Subschema" -s base "(objectclass=*)" +
For slapd 2.4.18 on Ubuntu 9.10, these additional steps may help:
# Reindex the database
slapindex -F /etc/ldap/slapd.d
# Verify database integrity
slapcat -b "cn=config" > /tmp/config.ldif
Network-level restrictions might be interfering:
# Check local firewall rules
iptables -L -n
# For SELinux systems
getsebool -a | grep ldap
When standard methods fail, try these advanced techniques:
# Run slapd in debug mode
slapd -d 256 -h "ldap:/// ldapi:///"
# Check for corrupted indices
db_recover -h /var/lib/ldap