Tag Archives: ldap

PHP 5: ldap_search never returns when searching Active Directory

I recently moved a PHP web application from a server running PHP 5.3 on Mac OS X 10.6 to a newer one with PHP 5.4 on Mac OS X 10.9. This caused the following code sample, run against an Active Directory server, to hang at the ldap_search() call:

$conn = ldap_connect('ldaps://' . $LDAPSERVER);
ldap_set_option($conn, LDAP_OPT_PROTOCOL_VERSION, 3);
$bind = @ldap_bind($conn, $LDAPUSER, $LDAPPW);
$result = ldap_search($conn, $LDAPSEARCHBASE, '(&(samaccountname=' . $searchuser . '))');
$info = ldap_get_entries($conn, $result);

Wiresharking the connection between web server and LDAP server (after replacing ldaps:// with ldap://) showed:

bindRequest(1) "$LDAPUSER" simplebindResponse(1) success searchRequest82) "$LDAPSEARCHBASE" wholeSubtree
searchResEntry(2) "CN=$searchuser,...,$LDAPSEARCHBASE" | searchResRef(2) | searchResDone(2) success [1 result]
bindRequest(4) "" simple
bindResponse(4) success
searchRequest(3) "DC=DomainDnsZones,$LDAPSEARCHBASE" wholeSubtree
searchResDone(3) operationsError (000004DC: LdapErr: DSID-0C0906E8, comment: In order to perform this operation a successful bind must be complete on the connection., data0,

So it’s binding, receiving a success response, searching and then receiving a response and a referrer to DC=DomainDnsZones,$LDAPSEARCHBASE. Next, it opens a new TCP connection and follows the referrer, but does an anonymous bind.

The solution is simple: just add

ldap_set_option($conn, LDAP_OPT_REFERRALS, FALSE);

after line 2. If for some reason you actually need to follow the referrer, have a look at ldap_set_rebind_proc, which lets you specify a callback which then does the authentication upon rebind.

Update August 2015: Same goes when using Net_LDAP3, which is used e.g. by Roundcube’s LDAP integration. Here you need to add the following:

$config['ldap_public']['public'] = array(
 'referrals' => false,

Hashing and verifying LDAP passwords in PHP

I recently migrated a PHP web application that used LDAP for authentication and MySQL for data to something entirely MySQL based. I needed the users to be able to continue using their old LDAP passwords, so I dumped the LDAP database and grabbed the userPassword field for each user, base64_decode()d it and wrote that to a MySQL table. These password hashes start with something like {crypt}, {MD5}, {SHA1} or {SSHA1}, or in very rare cases, are plain-text.

Here’s a PHP function I wrote that, given a plain-text $password, verifies it against such a $hash. This is what you’ll be calling from your authentication script to verify a given password against the hash.

function check_password($password, $hash)
 if ($hash == '') // no password
 //echo "No password";
 return FALSE;
 if ($hash{0} != '{') // plaintext password
 if ($password == $hash)
 return TRUE;
 return FALSE;
 if (substr($hash,0,7) == '{crypt}')
 if (crypt($password, substr($hash,7)) == substr($hash,7))
 return TRUE;
 return FALSE;
 elseif (substr($hash,0,5) == '{MD5}')
 $encrypted_password = '{MD5}' . base64_encode(md5( $password,TRUE));
 elseif (substr($hash,0,6) == '{SHA1}')
 $encrypted_password = '{SHA}' . base64_encode(sha1( $password, TRUE ));
 elseif (substr($hash,0,6) == '{SSHA}')
 $salt = substr(base64_decode(substr($hash,6)),20);
 $encrypted_password = '{SSHA}' . base64_encode(sha1( $password.$salt, TRUE ). $salt);
 echo "Unsupported password hash format";
 return FALSE;
 if ($hash == $encrypted_password)
 return TRUE;
 return FALSE;

And here’s one that make a {SSHA} hash from a password (I did not implement all the other algorithms as by today’s standards, they are no longer secure). This is what you’ll be calling from your change password script to hash the password for storing in the database.

function hash_password($password) // SSHA with random 4-character salt
 $salt = substr(str_shuffle(str_repeat('ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789',4)),0,4);
 return '{SSHA}' . base64_encode(sha1( $password.$salt, TRUE ). $salt);

Extending Active Directory for Mac OS X clients

After I wrote about building your own OpenDirectory server on Linux a while back, I decided to do the same thing on Windows Server 2008 R2. The process of extending the AD schema to include Apple classes and attributes is documented by Apple (this is the Leopard version of the document – if you don’t plan on having exclusively Snow Leopard clients, you can follow the newer version of the document that skips a couple of things that Snow Leopard no longer needs).

But since schema extensions are generally frowned upon in the Windows world because they’re irreversible (why the heck, Microsoft…?), I initially tried a dual-directory (golden triangle, magic triangle) type approach where I’d be augmenting my AD with Apple records coming from an AD LDS (Active Directory Lightweight Directory Services, previously called ADAM, Active Directory User Mode, which is basically a plain LDAP server from Microsoft). While this may sound like a great idea, I just couldn’t get it to work. After dozens of manual schema extensions to AD LDS (Microsoft doesn’t include many standard LDAP attributes, so I had to dig through the dependencies of apple.schema and even tried importing a complete OD schema), I gave up because I could not get Workgroup Manager to authenticate against it to allow me to make changes.

So the next thing to do was follow Apple’s AD schema extension guide (linked above) and do what everybody else did. This was rather straight-forward (managed preferences for users, groups and computers worked right away), but when I tried to create a computer list (which is not possible using Snow Leopard’s Server Admin Tools, but requires Tiger’s (which throw loads of errors on Snow Leopard but still get the job done) since Leopard introduced computer groups which however are not supported by the AD plugin), it just said I didn’t have permission to do that. After enabling DirectoryService debug logging (killall -USR1 DirectoryService && killall -USR2 DirectoryService), I traced it down to Active Directory: Add record CN=Untitled_1,CN=Mac OS X,DC=xxx,DC=zz with FAILED – LDAP Error 19 in /Library/Logs/DirectoryService/*. Apparently, that’s caused by some versions of ADSchemaAnalyzer setting objectClassCategory to 0 instead of 1 on all exported classes. Too bad AD schema extensions are irreversible and that’s one of the attributes you can’t change later on… 🙁 Well, with AD Schema Management MMC snap-in, I was able to rename the botched apple-computer-list class, defunct it and add a new one using ldifde. With some really wild hacking in the AD Schema using ADSI Editor, I was then able to  eventually get OS X to no longer look at the renamed attribute, but instead at the new one. To see whether you have been successful, killall DirectoryService, wait a few seconds and grep -H computer-list /Library/Preferences/DirectoryService/ActiveDirectory* will show a line indicating which class in the schema it’s using.

Once you’re there, everything should work as expected. If you don’t want to use Tiger’s Workgroup Manager to create old-style computer lists, you can do that in ADSI Editor and create apple-computer-list objects in the CN=Mac OS X branch by hand.

So, attached is the schema ldif that’s exactly the way it should be. I really wonder why Apple doesn’t provide it themselves – it’s going to turn out exactly like that every time you follow their guide on any Windows server… Apple Schema for Active Directory

I guess that the overall conclusion of this should be that AD schema extensions in general and specifically Mac OS X managed clients in AD environments are a nasty hack. I suppose the dual directory/magic triangle/golden triangle approach with a Microsoft AD and an Apple OD would work, but it requires maintaining two separate directories, which may not be that great in a larger environment either.

If Apple discontinues Mac OS X Server at some point in the near future (which the demise of the Xserve and the lack of announcements regarding Mac OS X 10.7 Server alongside Mac OS X Lion suggest), this is definitely something they need to improve. There are some third-party solutions that store MCX settings outside of AD (similar to Windows GPOs, which are stored on the SYSVOL share) such Thursby ADmitMac – however that’s a rather expensive solution (a dozen client licenses costs about as much as two Mac mini servers) and might break after OS updates (though from what I’ve heard, they’re rather quick at providing updates). If Apple does discontinue Mac OS X Server, they should definitely improve Lion’s AD integration to replicate ADmitMac’s features.

Building your own OpenDirectory server on Linux

OpenDirectory is a feature included with Mac OS X Server. Wouldn’t it be nice if you could use it without having to spend hundreds of dollars on a server license? Wouldn’t it be great if you could add it into your existing Linux-based OpenLDAP server? It’s actually quite easy because OpenDirectory is a standard OpenLDAP server with a special Apple schema.

0. Prerequisites
– OpenLDAP server with Samba integration (I’m runnig it on a Ubuntu 8.04 server, using the standard OpenLDAP and Samba packages). I won’t go into the details of how to set this up, there are lots of tutorials around the web on this.
– some kind of LDAP admin tool, I used phpLDAPAdmin
– Mac OS X 10.5 Leopard clients

1. Adding the Apple schema to your OpenDirectory server
It is located in /etc/openldap/schema/apple.schema on any Mac. Copy this file to your OpenLDAP server and add it to your slapd.conf.
You may run into the problem that apple.schema references some samba.schema entries that were deprecated with Samba 3. Specifically, these are acctFlags, pwdLastSet, logonTime, logoffTime, kickoffTime, homeDrive, scriptPath, profilePath, userWorkstations, smbHome, rid and primaryGroupID, so you’ll need to editapple.schema and replace these with their Samba 3 counterparts.
Now, restart the OpenLDAP daemon so it recognizes the changes.

2. Adding some Mac-specific attributes to your LDAP server
Add an ou=macosx branch to your LDAP tree, under which you’ll need to create ou=accesscontrols, ou=augments, ou=automountMap, ou=autoserversetup, ou=certificateauthorities, ou=computer_groups, ou=computer_lists, ou=computers, ou=filemakerservers, ou=locations, ou=machines, ou=maps, ou=mount, ou=neighborhoods, ou=places, ou=preset_computer_groups, ou=preset_computer_lists, ou=preset_computers, ou=preset_groups, ou=preset_users, ou=printers, and ou=resources.
To all your LDAP groups, add the apple-group objectClass. To all your LDAP users, add the apple-user objectClass.

3. Connecting your Mac to the LDAP directory
On your Mac, go into Directory Access and add your LDAP server. Choose OpenDirectory as the server type and adjust the Samba mappings to match your changes from step 1. Here is a plist you can import into Directory Access that already has these mappings corrected: LDAPv3_Unix_Samba3_OD.plist.
If you want your other clients to automatically use this mapping, create a cn=config branch in your LDAP tree and use the Write to Server button in Directory Access.

4. Use Workgroup Manager to set network home folders, managed preferences, …
Now, you can use Workgroup Manager to manage network home folders and managed preferences, just like you would on a Mac server.  You’ll need to authenticate using an LDAP user who has full write privileges to the directory (as set in slapd.conf). The standard cn=admin,dc=example,dc=com user will NOT work.

5. Conclusion
Almost everything works, except for:
– adding new users and group through Workgroup Manager
– solution: unknown
– assigning directory admin privileges to users through Workgroup Manager
– solution: using an OpenLDAP server set up to use cn=config instead of slapd.conf. This will also require going into Directory Access again and adding the OLCBDBConfig, OLCFrontEndConfig, OCGlobalConfig, OLCSchemaConfig and OLCOverlayDynamicID record types back in (they are included in the OpenDirectory mapping, but I deleted them from mine because they only cause error messages on an OpenLDAP server with slapd.conf configuration).

Here are all the web sites that helped me in the process of figuring this out:
http://docs.info.apple.com/article.html?path=ServerAdmin/10.4/en/c6od15.html (this one is especially important because it explains what to do if your LDAP server is not set up for SASL authentication)
http://www.emmes-world.de/mac-afp-homes.html (this one describes a similar setup and was my most important resource)

7. Further Information
Since you’re not using Kerberos for authentication, you may want to look at securing your LDAP connections with SSL. Here are some links that talk about it:

Someone else also wrote a blog post about Setting up a Linux server for OS X clients, in which they also describe how to incorporate Kerberos into the whole equation. That’s certainly something worth considering.