Configuring OpenLDAP as a Active Directory Proxy
- by vadensumbra
We try to set up an Active Directory server for company-wide authentication.
Some of the servers that should authenticate against the AD are placed in a DMZ, so we thought of using a LDAP-server as a proxy, so that only 1 server in the DMZ has to connect to the LAN where the AD-server is placed).
With some googling it was no problem to configure the slapd (see slapd.conf below) and it seemed to work when using the ldapsearch tool, so we tried to use it in apache2 htaccess to authenticate the user over the LDAP-proxy.
And here comes the problem:
We found out the username in the AD is stored in the attribute 'sAMAccountName' so we configured it in .htaccess (see below) but the login didn't work.
In the syslog we found out that the filter for the ldapsearch was not (like it should be) '(&(objectClass=*)(sAMAccountName=authtest01))' but '(&(objectClass=*)(?=undefined))' which we found out is slapd's way to show that the attribute do not exists or the value is syntactically wrong for this attribute.
We thought of a missing schema and found the microsoft.schema (and the .std / .ext ones of it) and tried to include them in the slapd.conf. Which does not work. We found no working schemata so we just picked out the part about the sAMAccountName and build a microsoft.minimal.schema (see below) that we included. Now we get the more precise log in the syslog:
Jun 16 13:32:04 breauthsrv01 slapd[21229]: get_ava: illegal value for attributeType sAMAccountName
Jun 16 13:32:04 breauthsrv01 slapd[21229]: conn=0 op=1 SRCH base="ou=oraise,dc=int,dc=oraise,dc=de" scope=2 deref=3 filter="(&(objectClass=\*)(?sAMAccountName=authtest01))"
Jun 16 13:32:04 breauthsrv01 slapd[21229]: conn=0 op=1 SRCH attr=sAMAccountName
Jun 16 13:32:04 breauthsrv01 slapd[21229]: conn=0 op=1 SEARCH RESULT tag=101 err=0 nentries=0 text=
Using our Apache htaccess directly with the AD via LDAP works though.
Anyone got a working setup? Thanks for any help in advance:
slapd.conf:
allow bind_v2
include /etc/ldap/schema/core.schema
...
include /etc/ldap/schema/microsoft.minimal.schema
...
backend ldap
database ldap
suffix "ou=xxx,dc=int,dc=xxx,dc=de"
uri "ldap://80.156.177.161:389"
acl-bind bindmethod=simple binddn="CN=authtest01,ou=GPO-Test,ou=xxx,dc=int,dc=xxx,dc=de" credentials=xxxxx
.htaccess:
AuthBasicProvider ldap
AuthType basic
AuthName "AuthTest"
AuthLDAPURL "ldap://breauthsrv01.xxx.de:389/OU=xxx,DC=int,DC=xxx,DC=de?sAMAccountName?sub"
AuthzLDAPAuthoritative On
AuthLDAPGroupAttribute member
AuthLDAPBindDN CN=authtest02,OU=GPO-Test,OU=xxx,DC=int,DC=xxx,DC=de
AuthLDAPBindPassword test123
Require valid-user
microsoft.minimal.schema:
attributetype ( 1.2.840.113556.1.4.221
NAME 'sAMAccountName'
SYNTAX '1.3.6.1.4.1.1466.115.121.1.15'
SINGLE-VALUE )
