LDAP

OMERO LDAP Authentication

LDAP is an open standard for querying and modifying directory services that is commonly used for authentication, authorization and accounting (AAA). OMERO.server supports the use of an LDAP server to query (but not modify) AAA information for the purposes of automatic user creation.

This allows OMERO users, ''Experimenters'' or ''Scientists'' in OMERO parlance, to be automatically created and placed in groups according to your existing institution policies. This can significantly simplify your user administration burden.

The OMERO.server LDAP implementation can handle a number of use cases. For example,

Allow every ''inetOrgPerson'' under omero.ldap.base to login
but restrict access based upon an arbitrary LDAP filter, e.g. "omero.ldap.user_filter=(memberOf=dn=someGroup,ou=Lab,o=College)"
and add that user to some number of groups, e.g. "omero.ldap.new_user_group=:query:(member=@{dn})"

How it works

On login, the username provided is searched for in OMERO. If the name does not exist, then the LDAP plugin is queried for a username matching the system-wide user filter. If such an LDAP entry exists and the password matches, a new user with the given username is created, and the user is added to any groups which match the new_user_group setting.

On subsequent logins, the user filter and the password are again checked the LDAP server, and if there is no longer a match, login is refused. If you would prefer to only have the user_filter applied during user creation and not on every login, see “Legacy Password Providers” below.

LDAP Properties

The LDAP plugin is configured via several configuration properties, all starting with "omero.ldap.". The default values for these properties is set in the file etc/omero.properties.

    omero.ldap.config=false
    omero.ldap.urls=ldap://localhost:389
    omero.ldap.username=
    omero.ldap.password=
    omero.ldap.base=ou=example,o=com

These properties are the base requirements for logging in to LDAP. After having configured your connection, you can turn the LDAP on and off between restarts by setting "omero.ldap.config" to false.

    omero.ldap.user_filter=(objectClass=person)
    omero.ldap.user_mapping=omeName=cn,firstName=givenName,lastName=sn,email=mail

These two user properties are used to look up users by login name and, if necessary, create new users based on the information in LDAP. "omero.ldap.user_filter" will be AND'ed to the username query, and can contain any valid LDAP filter string. The username query is taken from the LDAP attribute which gets mapped to "omeName" by "omero.ldap.user_mapping". Here, the "cn" is mapped to omeName, so the username query is (cn=[login name]). The final query is (&(objectClass=person)(cn=[login name])), which must return a single result to be considered valid.

    omero.ldap.group_filter=(objectClass=groupOfNames)
    omero.ldap.group_mapping=name=cn
    omero.ldap.new_user_group=default

The final set of properties are all concerned with what groups a user will be placed in on creation. The group filter and group mapping work just as the user filter and mapping do, but may not be used depending on the value of "new_user_group", which can have five separate meanings:

If equal to ":ou:", then a user's last organizational unit will be used as his or her group. For example, the user with the dn "cn=frank,ou=TheLab,ou=LifeSciences,o=TheCollege" will be placed in the group "TheLab".
If prefixed with ":attribute:", then the rest of the string is taken to be an attribute all of whose values will be taken as group names. For example, "omero.ldap.new_user_group=:attribute:memberOf" would add a user to all the groups named by memberOf.
If prefixed with ":query:", then the rest of the value is taken as a query to be AND'ed to the group filter. In the query, values from the user such as "@{cn}", "@{email}", or "@{dn}" can be used as place holders.
If prefixed with ":bean:", then the rest of the string is the name of a Spring bean which implements the NewUserGroupBean interface. See the developer documentation for more info.
If not prefixed at all, then the value is simply the name of a group which all users from LDAP should be added to.

LDAP Configuration

Like many pieces of OMERO.server configuration, LDAP-specific configuration is done by specifying extra properties during installation. The default values for the LDAP properties are listed in the etc/omero.properties file inside your OMERO installation directory. NOTE: Please remember that once a change has been made, a server restart will be needed.

Change any settings that are necessary via bin/omero config.

Enable or disable LDAP (true/false)

bin/omero config set omero.ldap.config true

LDAP server URL string
```
bin/omero config set omero.ldap.urls ldap://ldap.example.com:389
```
NOTE: A SSL URL above should look like this: ldaps://ldap.example.com:636

LDAP server bind DN (if required; can be empty)

bin/omero config set omero.ldap.username cn=Manager,dc=example,dc=com

LDAP server bind password (if required; can be empty)
```
bin/omero config set omero.ldap.password secret
```

LDAP server base search DN

bin/omero config set omero.ldap.base dc=example,dc=com

The filter applied to all users; can be empty in which case any LDAP user is valid
```
bin/omero config set omero.ldap.user_filter '(objectClass=inetOrgPerson)'
```

LDAP over SSL

If you are connecting to your server over SSL, that is, if your URL is of the form "ldaps://ldap.example.com:636" you will need to configure a key and trust store for Java. See the Security page for more information.

Synchronising LDAP on user login

This feature allows for LDAP to be considered the authority on user/group membership. With the following settings enabled each time a user logs in to OMERO their LDAP groups will be read from the LDAP server and reflected in OMERO. Enabling this will result in any bespoke OMERO groups that have been created being removed from the user's profile. The groups will still exist on the server but the association between user and group will not be reflected unless such a link is made in LDAP.

<property name="omero.ldap.sync_on_login" value="true"/>

bin/omero config set omero.ldap.sync_on_login true

Legacy Password Providers

The primary component of the LDAP plugin is the LdapPasswordProvider, which is responsible for creating users, checking their passwords, and adding them to or removing them from groups. The default password provider is the “chainedPasswordProvider” which first checks LDAP if LDAP is enabled, and then checks JDBC. This can explicitly be enabled by executing the system admin command

    bin/omero config set omero.security.password_provider chainedPasswordProvider

When the LDAP password provider implementation changes, previous versions can be configured as necessary.

chainedPasswordProvider431

With the 431 password provider, the user filter is only checked on first login and not kept on subsequent logins. This allows for an OMERO admin to change the username of a user in omero to be different than the one kept in LDAP. To enable it, use:

    bin/omero config set omero.security.password_provider chainedPasswordProvider431

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