I'm attempting to use OpenLDAP as a proxy to an Active Directory domain. Using the ldap backend, I'm able to configure the proxy and that configuration seems to be working well. But account entries are frequently moved from ou to ou in a domain and Microsoft permits the bind DN to be a userPrincipalName attribute value of the entry instead of the full DN of the account; this features avoids having to make many bind DN application configuration changes.
With just the ldap backend configured, OpenLDAP rejects the userPrincipalName (UPN) bind DN as an invalid DN. To work around this error, I was trying to see if I could use the rwm overlay to detect the UPN and convert to the actual domain entry DN using an attribute map. If I use the form mail=UPN the map works as expected; however, if I only provide the UPN as the bind DN, OpenLDAP still rejects it as an invalid DN. I suspect that the rwm overlay manipulations to not take effect until after the bind DN syntax is checked. I wanted to confirm my suspicion and see if any one else has been able to get a UPN-based bind to work through OpenLDAP. For reference my slapd.conf configuration is below: ### Schema includes ########################################################### include /etc/openldap/schema/core.schema include /etc/openldap/schema/cosine.schema include /etc/openldap/schema/inetorgperson.schema include /etc/openldap/schema/misc.schema include /etc/openldap/schema/nis.schema ## Module paths ############################################################## modulepath /usr/lib64/openldap/ moduleload rwm # Main settings ############################################################### loglevel 8 sizelimit unlimited idletimeout 600 writetimeout 30 allow bind_v2 pidfile /var/openldap/mycompany/var/slapd.pid argsfile /var/openldap/mycompany/var/slapd.args logfile /var/openldap/mycompany/logs/access TLSCertificateFile /var/openldap/mycompany/certs/Server.pem TLSCertificateKeyFile /var/openldap/mycompany/certs/Server.key TLSCACertificateFile /var/openldap/mycompany/certs/ServerCA.pem ### Rewrite rules ############################################################# # Bind with UPN instead of full DN: we first need # an ldap map that turns attributes into a DN (the # argument used when invoking the map is appended to # the URI and acts as the filter portion) overlay rwm rwm-suffixMassage "" "dc=mycompany,dc=com" rwm-rewriteMap ldap attr2dn "ldaps://mycompany.com/ou=Domain%20Users,dc=mycompany,dc=com?dn?sub" bindwhen=now version=3 binddn="CN=mybindacct,ou=Domain Users,DC=mycompany,DC=com" credentials=****** # Then we need to detect UPN DN # note that the rule in case of match stops rewriting # In case we are mapping virtual # to real naming contexts, we also need to rewrite # regular DNs, because the definition of a bindDN # rewrite context overrides the default definition. rwm-rewriteContext bindDN rwm-rewriteRule "^[^=,][email protected]$" "mail=$0" ":" rwm-rewriteRule "^mail=[^,][email protected]$" "${attr2dn($0)}" ":@" ### Database definition (Proxy to AD) ######################################### database ldap readonly yes protocol-version 3 rebind-as-user uri "ldaps://mycompany.com" suffix "dc=mycompany,dc=com" Thanks, Steve Vandenburgh This communication is the property of CenturyLink and may contain confidential or privileged information. Unauthorized use of this communication is strictly prohibited and may be unlawful. If you have received this communication in error, please immediately notify the sender by reply e-mail and destroy all copies of the communication and any attachments.
