LDAP

LDAP Overview

LDAP uses in ZCS

LDAP is used in ZCS to store data for

• Global configuration
• USER and Authentication
• SERVER
• DOMAIN
• COS

Additionally, information relating to:

• External Authentication
• External GAL

Most of this data can be viewed and configured via the Admin Console or with zmprov.

LDAP in the system architecture

In every ZCS installation, there will be one and only one Master LDAP server. This server is authoritative for user information, server configuration, etc.

Additionally, one or more Replicas may be defined, to improve performance and reduce the load on the Master.

During installation in a multi-server environment, the LDAP server must be the first installed and configured, and must be running during any subsequent installations. The LDAP server must also be the first started in a multi-server environment.

LDAP troubleshooting

If you're seeing ERROR: service.FAILURE (system failure: getDirectContext) (cause: javax.naming.CommunicationException localhost.localdomain:389) on installation, you're in the right place.

Installation Problems

LDAP initialization generally fails due to the following

• Failure to start the LDAP server
• Failure to resolve the LDAP server
• Failure to connect to the LDAP server

Startup failures

The startup of the LDAP server during installation happens when the initialization script calls the ldap start script.

If this startup fails, all further initialization fails.

Detecting startup failure

After the initialization script exits (successfully or otherwise) slapd should be running. To verify that the slapd process is running:

 ps auxww | grep zimbra | grep slapd
 Should return a line containing:
 /opt/zimbra/openldap/libexec/slapd -l LOCAL0 -4 -u zimbra -h ldaps:// ldap://:389/ -f /opt/zimbra/conf/slapd.conf

If there is no output, LDAP is not starting. See the next section

If this line is present, verify that the zimbra system is detecting it (run as the zimbra user):

 ldap status

A return of:

 slapd running pid: 7568  (your PID will vary)

is successful.

If you get no such response from the ldap status command, it's likely that the running slapd process is hanging around from a previous installation. To kill it manually:

 killall -TERM slapd
 ps auxww | grep zimbra | grep slapd

If the process is still there, determine it's PID (second column in the ps output) and

 kill -9 PID

After cleaning up old LDAP processes, you should re-attempt the initialization by re-running zmsetup.pl

Correcting startup failure

If the previous section indicates that ldap is not starting at all, attempt ldap startup manually (as the zimbra user);

 sh -x bin/ldap start

output from this should indicate the source of the problem

LDAP and DNS

LDAP uses DNS to resolve the ldap host, even if it's localhost

To verify that you're able to resolve the ldap host:

host ldap-hostname

Make sure you understand DNS.

Failure to Connect

To detect connection failure (using the hostname configured for the ldap server):

 telnet ldap hostname 389

If this times out, or the connection is refused, there could be several causes.

If resolution succeeds, the initialization may fail because the LDAP server failed to start

Firewall problems

If the server is running a local firewall, make sure it's allowing port 389 connections.

If the ldap hostname resolves to a public IP on an external firewall, make sure that firewall is allowing connections through on port 389.

Provisioning users in LDAP

The basic form for this is:

 zmprov ca username@domain password 

Additional attributes can be specified on the same command:

 zmprov ca username@domain password attribute value attribute value

For creation of a single user, the admin console is the preferred method. If you need to bulk provision users, during initial installation, it can be easier to create a script.

EXAMPLE - creating several users at once:

Create a file containing all of the zmprov commands that you wish to run:

 ca user1 user1pass
 ca user2 user2pass
 ca user3 user3pass
 ca adminuser adminuserpass zimbraIsAdminAccount TRUE
 ca user4 user4pass zimbraMailAlias user_4 zimbraMailAlias user_four zimbraMailAlias user.four
 ca nopassuser 

Save this file (eg, usercreate.txt ). Then, run zmprov, redirecting standard input from this file:

 zmprov < usercreate.txt

With this method, it's relatively straightforward to dump an existing ldap directory into a text file, format it for zmprov, and bulk-provision the users in the ZCS LDAP instance.

If you are using external LDAP authentication you can create the users with no local password by supplying the empty string "" after the username

LDAP replication

Installation

Your LDAP Master server (machine 1) should be installed using normal ZCS installation options. The replica will be installed on a separate server (machine 2).

To install this server:

• Use standard install.sh options, including the zimbra-ldap server.
• Set the zimbra-ldap server to DISABLED. This is very important, as if you leave it set to Enabled, it will just create a new directory server and you'll have two separate mail systems.
• Set the master LDAP server for machine 2 to be machine 1.
• Make sure the master is up and running before you apply the configuration to machine 2 and complete the installation.
• Installation will complete as normal, and both servers will have their ZCS servers up, except for slapd on machine 2.

If you want to install an LDAP replica on a previously existing Zimbra server, you will need to use install.sh to install zimbra-ldap on the server. When install.sh asks if you wish to perform an upgrade, select Yes, then select Yes when it asks to install zimbra-ldap. The rest of the install will be similar to installing a disabled LDAP server on a new box.

Replica Configuration

After the servers are up, you need to set up a few things before the replica can be brought up.

• Run zmsshkeygen on both servers. This will set up SSH keys for both.
• Run zmupdateauthkeys on both servers. This will set up trusted authentication between the two machines for the purposes of running zmrcd.
• Run zmldapenablereplica on machine 2. This will set up the replication account in the directory and will make a copy of the master on machine 2. This should run cleanly.
• You may have to run zmcreatecert on machine 2 to create the conf/slapd.crt file. Just run it with no command line options. If this file is not present, slapd will not start.

When this is complete, you're done. You can test the replica by creating a few accounts through the administrative interface on the master server. You should be able to see them immediately with an LDAP search run against machine 2.

Using the Replica

To use the replica LDAP server after you've tested it, you now need to update the ldap_url value on the Zimbra servers you wish to have query the replica instead of the master. (Any services running on the replica server itself will automatically query the replica first.)

Use the ldap_url value set on the replica server as a template value (zmlocalconfig ldap_url). For each server you want to change:

• Stop the zimbra services on that server
• Update the ldap_url value (zmlocalconfig -e ldap_url="url url url") (quotes needed because of the space)
• Then start the services again

Moving an LDAP Master

This procedure shows how to move the LDAP Master from one host to another. This is not recommended for use by those without at least some LDAP expertise, and could result in trouble for your system. It should be performed only if it is necessary to move the Master LDAP server from its current server to another.

To move the master LDAP directory:

• Create a replica on the machine that will become the new master using the instructions from LDAP Replication.
• Start services on all servers and ensure that the replica is picking up LDAP updates from the master.
• If everything is running correctly, shut down all servers again.
• On the new LDAP master, make a backup copy of $ZIMBRA_HOME/conf/slapd.conf. Remove the replication-related lines at the end of the file. This will be everything below TLSCACertificateFile /opt/zimbra/conf/ca/ca.pem.
• Edit zmlocalconfig on all hosts so that ldap_master_url and ldap_url now point to the new directory master.
• Edit zmlocalconfig on the new directory master so that ldap_is_master is set to true.
• Edit zmlocalconfig on the old directory master so that ldap_is_master is set to false.
• Start up services on all servers, starting with the new directory master.

At this point, services should be up and running on all hosts, and they should all be working off the new LDAP master. The old LDAP master can be disabled, or it can be converted into a replica by shutting it down, removing the contents of its openldap-data directory, and running zmldapenablereplica.