Apache Module mod_authnz_ldap

Summary

This module allows authentication front-ends such asmod_auth_basic to authenticate users through an ldap directory.

mod_authnz_ldap supports the following features:

• Known to support theOpenLDAP SDK (both 1.x and 2.x), Novell LDAP SDK and theiPlanet (Netscape) SDK.
• Complex authorization policies can be implemented by representing the policy with LDAP filters.
• Uses extensive caching of LDAP operations viamod_ldap.
• Support for LDAP over SSL (requires the Netscape SDK) or TLS (requires the OpenLDAP 2.x SDK or Novell LDAP SDK).

When usingmod_auth_basic, this module is invoked via theAuthBasicProvider directive with theldap value.

Topics

• Contents
• General caveats
• Operation
• The Require Directives
• Examples
• Using TLS
• Using SSL
• Exposing Login Information
• Using Active Directory
• Using Microsoft FrontPage with mod_authnz_ldap

Directives

• AuthLDAPAuthorizePrefix
• AuthLDAPBindAuthoritative
• AuthLDAPBindDN
• AuthLDAPBindPassword
• AuthLDAPCharsetConfig
• AuthLDAPCompareAsUser
• AuthLDAPCompareDNOnServer
• AuthLDAPDereferenceAliases
• AuthLDAPGroupAttribute
• AuthLDAPGroupAttributeIsDN
• AuthLDAPInitialBindAsUser
• AuthLDAPInitialBindPattern
• AuthLDAPMaxSubGroupDepth
• AuthLDAPRemoteUserAttribute
• AuthLDAPRemoteUserIsDN
• AuthLDAPSearchAsUser
• AuthLDAPSubGroupAttribute
• AuthLDAPSubGroupClass
• AuthLDAPURL

Bugfix checklist

• httpd changelog
• Known issues
• Report a bug

See also

• mod_ldap
• mod_auth_basic
• mod_authz_user
• mod_authz_groupfile
• Comments

Contents

• General caveats
• Operation
  • The Authentication Phase
  • The Authorization Phase
• The Require Directives
  • Require ldap-user
  • Require ldap-group
  • Require ldap-dn
  • Require ldap-attribute
  • Require ldap-filter
  • Require ldap-search
• Examples
• Using TLS
• Using SSL
• Exposing Login Information
• Using Active Directory
• Using Microsoft FrontPage withmod_authnz_ldap
  • How It Works
  • Caveats

General caveats

This module caches authentication and authorization results basedon the configuration ofmod_ldap. Changesmade to the backing LDAP server will not be immediately reflected on theHTTP Server, including but not limited to user lockouts/revocations, password changes, or changes to group memberships. Consult the directives inmod_ldap for details of the cache tunables.

Operation

There are two phases in granting access to a user. The first phase is authentication, in which themod_authnz_ldap authentication provider verifies that the user's credentials are valid. This is also called thesearch/bind phase. The second phase is authorization, in whichmod_authnz_ldap determines if the authenticated user is allowed access to the resource in question. This is also known as thecompare phase.

mod_authnz_ldap registers both an authn_ldap authentication provider and an authz_ldap authorization handler. The authn_ldap authentication provider can be enabled through theAuthBasicProvider directive using theldap value. The authz_ldap handler extends theRequire directive's authorization types by addingldap-user,ldap-dn andldap-group values.

The Authentication Phase

During the authentication phase,mod_authnz_ldap searches for an entry in the directory that matches the username that the HTTP client passes. If a single unique match is found, thenmod_authnz_ldap attempts to bind to the directory server using the DN of the entry plus the password provided by the HTTP client. Because it does a search, then a bind, it is often referred to as the search/bind phase. Here are the steps taken during the search/bind phase.

1. Generate a search filter by combining the attribute and filter provided in theAuthLDAPURL directive with the username passed by the HTTP client.
2. Search the directory using the generated filter. If the search does not return exactly one entry, deny or decline access.
3. Fetch the distinguished name of the entry retrieved from the search and attempt to bind to the LDAP server using that DN and the password passed by the HTTP client. If the bind is unsuccessful, deny or decline access.

The following directives are used during the search/bind phase

The Authorization Phase

During the authorization phase,mod_authnz_ldap attempts to determine if the user is authorized to access the resource. Many of these checks requiremod_authnz_ldap to do a compare operation on the LDAP server. This is why this phase is often referred to as the compare phase.mod_authnz_ldap accepts the followingRequire directives to determine if the credentials are acceptable:

• Grant access if there is aRequire ldap-user directive, and the username in the directive matches the username passed by the client.
• Grant access if there is aRequire ldap-dn directive, and the DN in the directive matches the DN fetched from the LDAP directory.
• Grant access if there is aRequire ldap-group directive, and the DN fetched from the LDAP directory (or the username passed by the client) occurs in the LDAP group or, potentially, in one of its sub-groups.
• Grant access if there is aRequire ldap-attribute directive, and the attribute fetched from the LDAP directory matches the given value.
• Grant access if there is aRequire ldap-filter directive, and the search filter successfully finds a single user object that matches the dn of the authenticated user.
• Grant access if there is aRequire ldap-search directive, and the search filter successfully returns a single matching object with any distinguished name.
• otherwise, deny or decline access

OtherRequire values may also be used which may require loading additional authorization modules.

• Grant access to all successfully authenticated users if there is aRequire valid-user directive. (requiresmod_authz_user)
• Grant access if there is aRequire group directive, andmod_authz_groupfile has been loaded with theAuthGroupFile directive set.
• others...

mod_authnz_ldap uses the following directives during the compare phase:

The Require Directives

Apache'sRequire directives are used during the authorization phase to ensure that a user is allowed to access a resource. mod_authnz_ldap extends the authorization types withldap-user,ldap-dn,ldap-group,ldap-attribute andldap-filter. Other authorization types may also be used but may require that additional authorization modules be loaded.

Since v2.4.8,expressions are supported within the LDAP require directives.

Require ldap-user

TheRequire ldap-user directive specifies what usernames can access the resource. Oncemod_authnz_ldap has retrieved a unique DN from the directory, it does an LDAP compare operation using the username specified in theRequire ldap-user to see if that username is part of the just-fetched LDAP entry. Multiple users can be granted access by putting multiple usernames on the line, separated with spaces. If a username has a space in it, then it must be surrounded with double quotes. Multiple users can also be granted access by using multipleRequire ldap-user directives, with one user per line. For example, with aAuthLDAPURL ofldap://ldap/o=Example?cn (i.e.,cn is used for searches), the following Require directives could be used to restrict access:

Require ldap-user "Barbara Jenson"Require ldap-user "Fred User"Require ldap-user "Joe Manager"

Because of the way thatmod_authnz_ldap handles this directive, Barbara Jenson could sign on asBarbara Jenson,Babs Jenson or any othercn that she has in her LDAP entry. Only the singleRequire ldap-user line is needed to support all values of the attribute in the user's entry.

If theuid attribute was used instead of thecn attribute in the URL above, the above three lines could be condensed to

Require ldap-user bjenson fuser jmanager

Require ldap-group

This directive specifies an LDAP group whose members are allowed access. It takes the distinguished name of the LDAP group. Note: Do not surround the group name with quotes. For example, assume that the following entry existed in the LDAP directory:

dn: cn=Administrators, o=ExampleobjectClass: groupOfUniqueNamesuniqueMember: cn=Barbara Jenson, o=ExampleuniqueMember: cn=Fred User, o=Example

The following directive would grant access to both Fred and Barbara:

Require ldap-group cn=Administrators, o=Example

Members can also be found within sub-groups of a specified LDAP group ifAuthLDAPMaxSubGroupDepth is set to a value greater than 0. For example, assume the following entries exist in the LDAP directory:

dn: cn=Employees, o=ExampleobjectClass: groupOfUniqueNamesuniqueMember: cn=Managers, o=ExampleuniqueMember: cn=Administrators, o=ExampleuniqueMember: cn=Users, o=Exampledn: cn=Managers, o=ExampleobjectClass: groupOfUniqueNamesuniqueMember: cn=Bob Ellis, o=ExampleuniqueMember: cn=Tom Jackson, o=Exampledn: cn=Administrators, o=ExampleobjectClass: groupOfUniqueNamesuniqueMember: cn=Barbara Jenson, o=ExampleuniqueMember: cn=Fred User, o=Exampledn: cn=Users, o=ExampleobjectClass: groupOfUniqueNamesuniqueMember: cn=Allan Jefferson, o=ExampleuniqueMember: cn=Paul Tilley, o=ExampleuniqueMember: cn=Temporary Employees, o=Exampledn: cn=Temporary Employees, o=ExampleobjectClass: groupOfUniqueNamesuniqueMember: cn=Jim Swenson, o=ExampleuniqueMember: cn=Elliot Rhodes, o=Example

The following directives would allow access for Bob Ellis, Tom Jackson, Barbara Jenson, Fred User, Allan Jefferson, and Paul Tilley but would not allow access for Jim Swenson, or Elliot Rhodes (since they are at a sub-group depth of 2):

Require ldap-group cn=Employees, o=ExampleAuthLDAPMaxSubGroupDepth 1

Behavior of this directive is modified by theAuthLDAPGroupAttribute,AuthLDAPGroupAttributeIsDN,AuthLDAPMaxSubGroupDepth,AuthLDAPSubGroupAttribute, andAuthLDAPSubGroupClass directives.

Require ldap-dn

TheRequire ldap-dn directive allows the administrator to grant access based on distinguished names. It specifies a DN that must match for access to be granted. If the distinguished name that was retrieved from the directory server matches the distinguished name in theRequire ldap-dn, then authorization is granted. Note: do not surround the distinguished name with quotes.

The following directive would grant access to a specific DN:

Require ldap-dn cn=Barbara Jenson, o=Example

Behavior of this directive is modified by theAuthLDAPCompareDNOnServer directive.

Require ldap-attribute

TheRequire ldap-attribute directive allows the administrator to grant access based on attributes of the authenticated user in the LDAP directory. If the attribute in the directory matches the value given in the configuration, access is granted.

The following directive would grant access to anyone with the attribute employeeType = active

Require ldap-attribute employeeType="active"

Multiple attribute/value pairs can be specified on the same line separated by spaces or they can be specified in multipleRequire ldap-attribute directives. The effect of listing multiple attribute/values pairs is an OR operation. Access will be granted if any of the listed attribute values match the value of the corresponding attribute in the user object. If the value of the attribute contains a space, only the value must be within double quotes.

The following directive would grant access to anyone with the city attribute equal to "San Jose" or status equal to "Active"

Require ldap-attribute city="San Jose" status="active"

Require ldap-filter

TheRequire ldap-filter directive allows the administrator to grant access based on a complex LDAP search filter. If the dn returned by the filter search matches the authenticated user dn, access is granted.

The following directive would grant access to anyone having a cell phone and is in the marketing department

Require ldap-filter "&(cell=*)(department=marketing)"

The difference between theRequire ldap-filter directive and theRequire ldap-attribute directive is thatldap-filter performs a search operation on the LDAP directory using the specified search filter rather than a simple attribute comparison. If a simple attribute comparison is all that is required, the comparison operation performed byldap-attribute will be faster than the search operation used byldap-filter especially within a large directory.

When using anexpression within the filter, care must be taken to ensure that LDAP filters are escaped correctly to guard against LDAP injection. The ldap function can be used for this purpose.

<LocationMatch ^/dav/(?<SITENAME>[^/]+)/>  Require ldap-filter (memberOf=cn=%{ldap:%{unescape:%{env:MATCH_SITENAME}},ou=Websites,o=Example)</LocationMatch>

Require ldap-search

TheRequire ldap-search directive allows the administrator to grant access based on a generic LDAP search filter using anexpression. If there is exactly one match to the search filter, regardless of the distinguished name, access is granted.

The following directive would grant access to URLs that match the given objects in the LDAP server:

<LocationMatch ^/dav/(?<SITENAME>[^/]+)/>Require ldap-search (cn=%{ldap:%{unescape:%{env:MATCH_SITENAME}} Website)</LocationMatch>

Note: care must be taken to ensure that any expressions are properly escaped to guard against LDAP injection. Theldap function can be used as per the example above.

Examples

• Grant access to anyone who exists in the LDAP directory, using their UID for searches.

  AuthLDAPURL "ldap://ldap1.example.com:389/ou=People, o=Example?uid?sub?(objectClass=*)"Require valid-user

• The next example is the same as above; but with the fields that have useful defaults omitted. Also, note the use of a redundant LDAP server.

  AuthLDAPURL "ldap://ldap1.example.com ldap2.example.com/ou=People, o=Example"Require valid-user

• The next example is similar to the previous one, but it uses the common name instead of the UID. Note that this could be problematical if multiple people in the directory share the samecn, because a search oncnmust return exactly one entry. That's why this approach is not recommended: it's a better idea to choose an attribute that is guaranteed unique in your directory, such asuid.

  AuthLDAPURL "ldap://ldap.example.com/ou=People, o=Example?cn"Require valid-user

• Grant access to anybody in the Administrators group. The users must authenticate using their UID.

  AuthLDAPURL ldap://ldap.example.com/o=Example?uidRequire ldap-group cn=Administrators, o=Example

• Grant access to anybody in the group whose name matches the hostname of the virtual host. In this example anexpression is used to build the filter.

  AuthLDAPURL ldap://ldap.example.com/o=Example?uidRequire ldap-group cn=%{SERVER_NAME}, o=Example

• The next example assumes that everyone at Example who carries an alphanumeric pager will have an LDAP attribute ofqpagePagerID. The example will grant access only to people (authenticated via their UID) who have alphanumeric pagers:

  AuthLDAPURL ldap://ldap.example.com/o=Example?uid??(qpagePagerID=*)Require valid-user

• The next example demonstrates the power of using filters to accomplish complicated administrative requirements. Without filters, it would have been necessary to create a new LDAP group and ensure that the group's members remain synchronized with the pager users. This becomes trivial with filters. The goal is to grant access to anyone who has a pager, plus grant access to Joe Manager, who doesn't have a pager, but does need to access the same resource:

  AuthLDAPURL ldap://ldap.example.com/o=Example?uid??(|(qpagePagerID=*)(uid=jmanager))Require valid-user

  This last may look confusing at first, so it helps to evaluate what the search filter will look like based on who connects, as shown below. If Fred User connects asfuser, the filter would look like

  (&(|(qpagePagerID=*)(uid=jmanager))(uid=fuser))

  The above search will only succeed iffuser has a pager. When Joe Manager connects asjmanager, the filter looks like

  (&(|(qpagePagerID=*)(uid=jmanager))(uid=jmanager))

  The above search will succeed whetherjmanager has a pager or not.

Using TLS

To use TLS, see themod_ldap directivesLDAPTrustedClientCert,LDAPTrustedGlobalCert andLDAPTrustedMode.

An optional second parameter can be added to theAuthLDAPURL to override the default connection type set byLDAPTrustedMode. This will allow the connection established by anldap:// Url to be upgraded to a secure connection on the same port.

Using SSL

To use SSL, see themod_ldap directivesLDAPTrustedClientCert,LDAPTrustedGlobalCert andLDAPTrustedMode.

To specify a secure LDAP server, useldaps:// in theAuthLDAPURL directive, instead ofldap://.

Exposing Login Information

when this module performsauthentication, ldap attributes specified in theAuthLDAPURL directive are placed in environment variables with the prefix "AUTHENTICATE_".

when this module performsauthorization, ldap attributes specified in theAuthLDAPURL directive are placed in environment variables with the prefix "AUTHORIZE_".

If the attribute field contains the username, common name and telephone number of a user, a CGI program will have access to this information without the need to make a second independent LDAP query to gather this additional information.

This has the potential to dramatically simplify the coding and configuration required in some web applications.

Using Active Directory

An Active Directory installation may support multiple domains at the same time. To distinguish users between domains, an identifier called a User Principle Name (UPN) can be added to a user's entry in the directory. This UPN usually takes the form of the user's account name, followed by the domain components of the particular domain, for examplesomebody@nz.example.com.

You may wish to configure themod_authnz_ldap module to authenticate users present in any of the domains making up the Active Directory forest. In this way bothsomebody@nz.example.com andsomeone@au.example.com can be authenticated using the same query at the same time.

To make this practical, Active Directory supports the concept of a Global Catalog. This Global Catalog is a read only copy of selected attributes of all the Active Directory servers within the Active Directory forest. Querying the Global Catalog allows all the domains to be queried in a single query, without the query spanning servers over potentially slow links.

If enabled, the Global Catalog is an independent directory server that runs on port 3268 (3269 for SSL). To search for a user, do a subtree search for the attributeuserPrincipalName, with an empty search root, like so:

AuthLDAPBindDN apache@example.comAuthLDAPBindPassword passwordAuthLDAPURL ldap://10.0.0.1:3268/?userPrincipalName?sub

Users will need to enter their User Principal Name as a login, in the formsomebody@nz.example.com.

Using Microsoft FrontPage with mod_authnz_ldap

Normally, FrontPage uses FrontPage-web-specific user/group files (i.e., themod_authn_file andmod_authz_groupfile modules) to handle all authentication. Unfortunately, it is not possible to just change to LDAP authentication by adding the proper directives, because it will break thePermissions forms in the FrontPage client, which attempt to modify the standard text-based authorization files.

Once a FrontPage web has been created, adding LDAP authentication to it is a matter of adding the following directives toevery.htaccess file that gets created in the web

AuthLDAPURL       "the url"AuthGroupFile     "mygroupfile"Require group     "mygroupfile"

How It Works

FrontPage restricts access to a web by adding theRequire valid-user directive to the.htaccess files. TheRequire valid-user directive will succeed for any user who is validas far as LDAP is concerned. This means that anybody who has an entry in the LDAP directory is considered a valid user, whereas FrontPage considers only those people in the local user file to be valid. By substituting the ldap-group with group file authorization, Apache is allowed to consult the local user file (which is managed by FrontPage) - instead of LDAP - when handling authorizing the user.

Once directives have been added as specified above, FrontPage users will be able to perform all management operations from the FrontPage client.

Caveats

• When choosing the LDAP URL, the attribute to use for authentication should be something that will also be valid for putting into amod_authn_file user file. The user ID is ideal for this.
• When adding users via FrontPage, FrontPage administrators should choose usernames that already exist in the LDAP directory (for obvious reasons). Also, the password that the administrator enters into the form is ignored, since Apache will actually be authenticating against the password in the LDAP database, and not against the password in the local user file. This could cause confusion for web administrators.
• Apache must be compiled withmod_auth_basic,mod_authn_file andmod_authz_groupfile in order to use FrontPage support. This is because Apache will still use themod_authz_groupfile group file for determine the extent of a user's access to the FrontPage web.
• The directives must be put in the.htaccess files. Attempting to put them inside<Location> or<Directory> directives won't work. This is becausemod_authnz_ldap has to be able to grab theAuthGroupFile directive that is found in FrontPage.htaccess files so that it knows where to look for the valid user list. If themod_authnz_ldap directives aren't in the same.htaccess file as the FrontPage directives, then the hack won't work, becausemod_authnz_ldap will never get a chance to process the.htaccess file, and won't be able to find the FrontPage-managed user file.

AuthLDAPAuthorizePrefixDirective

This directive allows you to override the prefix used for environment variables set during LDAP authorization. IfAUTHENTICATE_ is specified, consumers of these environment variables see the same information whether LDAP has performed authentication, authorization, or both.

AuthLDAPBindAuthoritativeDirective

By default, subsequent authentication providers are only queried if a user cannot be mapped to a DN, but not if the user can be mapped to a DN and their password cannot be verified with an LDAP bind. IfAuthLDAPBindAuthoritative is set tooff, other configured authentication modules will have a chance to validate the user if the LDAP bind (with the current user's credentials) fails for any reason.

This allows users present in both LDAP andAuthUserFile to authenticate when the LDAP server is available but the user's account is locked or password is otherwise unusable.

See also

• AuthUserFile
• AuthBasicProvider

AuthLDAPBindDNDirective

An optional DN used to bind to the server when searching for entries. If not provided,mod_authnz_ldap will use an anonymous bind.

AuthLDAPBindPasswordDirective

A bind password to use in conjunction with the bind DN. Note that the bind password is probably sensitive data, and should be properly protected. You should only use theAuthLDAPBindDN andAuthLDAPBindPassword if you absolutely need them to search the directory.

If the value begins with exec: the resulting command will be executed and the first line returned to standard output by the program will be used as the password.

#Password used as-isAuthLDAPBindPassword secret#Run /path/to/program to get my passwordAuthLDAPBindPassword exec:/path/to/program#Run /path/to/otherProgram and provide argumentsAuthLDAPBindPassword "exec:/path/to/otherProgram argument1"

AuthLDAPCharsetConfigDirective

TheAuthLDAPCharsetConfig directive sets the location of the language to charset conversion configuration file.File-path is relative to theServerRoot. This file specifies the list of language extensions to character sets. Most administrators use the providedcharset.conv file, which associates common language extensions to character sets.

The file contains lines in the following format:

The case of the extension does not matter. Blank lines, and lines beginning with a hash character (#) are ignored.

AuthLDAPCompareAsUserDirective

When set, andmod_authnz_ldap has authenticated the user, LDAP comparisons for authorization use the queried distinguished name (DN) and HTTP basic authentication password of the authenticated user instead of the servers configured credentials.

Theldap-attribute,ldap-user, andldap-group (single-level only) authorization checks use comparisons.

This directive only has effect on the comparisons performed during nested group processing when AuthLDAPSearchAsUser is also enabled.

This directive should only be used when your LDAP server doesn't accept anonymous comparisons and you cannot use a dedicatedAuthLDAPBindDN.

See also

• AuthLDAPInitialBindAsUser
• AuthLDAPSearchAsUser

AuthLDAPCompareDNOnServerDirective

When set,mod_authnz_ldap will use the LDAP server to compare the DNs. This is the only foolproof way to compare DNs.mod_authnz_ldap will search the directory for the DN specified with theRequire dn directive, then, retrieve the DN and compare it with the DN retrieved from the user entry. If this directive is not set,mod_authnz_ldap simply does a string comparison. It is possible to get false negatives with this approach, but it is much faster. Note themod_ldap cache can speed up DN comparison in most situations.

AuthLDAPDereferenceAliasesDirective

This directive specifies whenmod_authnz_ldap will de-reference aliases during LDAP operations. The default isalways.

AuthLDAPGroupAttributeDirective

This directive specifies which LDAP attributes are used to check for user members within groups. Multiple attributes can be used by specifying this directive multiple times. If not specified, thenmod_authnz_ldap uses themember anduniqueMember attributes.

AuthLDAPGroupAttributeIsDNDirective

When seton, this directive says to use the distinguished name of the client username when checking for group membership. Otherwise, the username will be used. For example, assume that the client sent the usernamebjenson, which corresponds to the LDAP DNcn=Babs Jenson, o=Example. If this directive is set,mod_authnz_ldap will check if the group hascn=Babs Jenson, o=Example as a member. If this directive is not set, thenmod_authnz_ldap will check if the group hasbjenson as a member.

AuthLDAPInitialBindAsUserDirective

By default, the server either anonymously, or with a dedicated user and password, converts the basic authentication username into an LDAP distinguished name (DN). This directive forces the server to use the verbatim username and password provided by the incoming user to perform the initial DN search.

If the verbatim username can't directly bind, but needs some cosmetic transformation, see AuthLDAPInitialBindPattern.

This directive should only be used when your LDAP server doesn't accept anonymous searches and you cannot use a dedicatedAuthLDAPBindDN.

See also

• AuthLDAPInitialBindPattern
• AuthLDAPBindDN
• AuthLDAPCompareAsUser
• AuthLDAPSearchAsUser

AuthLDAPInitialBindPatternDirective

IfAuthLDAPInitialBindAsUser is set toON, the basic authentication username will be transformed according to the regular expression and substitution arguments.

The regular expression argument is compared against the current basic authentication username. The substitution argument may contain backreferences, but has no other variable interpolation.

This directive should only be used when your LDAP server doesn't accept anonymous searches and you cannot use a dedicatedAuthLDAPBindDN.

AuthLDAPInitialBindPattern (.+) $1@example.com

AuthLDAPInitialBindPattern (.+) cn=$1,dc=example,dc=com

See also

• AuthLDAPInitialBindAsUser
• AuthLDAPBindDN

AuthLDAPMaxSubGroupDepthDirective

When this directive is set to a non-zero valueX combined with use of theRequire ldap-group someGroupDN directive, the provided user credentials will be searched for as a member of thesomeGroupDN directory object or of any group member of the current group up to the maximum nesting levelX specified by this directive.

See theRequire ldap-group section for a more detailed example.

AuthLDAPRemoteUserAttributeDirective

If this directive is set, the value of theREMOTE_USER environment variable will be set to the value of the attribute specified. Make sure that this attribute is included in the list of attributes in theAuthLDAPURL definition, otherwise this directive will have no effect. This directive, if present, takes precedence overAuthLDAPRemoteUserIsDN. This directive is useful should you want people to log into a website using an email address, but a backend application expects the username as a userid.

AuthLDAPRemoteUserIsDNDirective

If this directive is set to on, the value of theREMOTE_USER environment variable will be set to the full distinguished name of the authenticated user, rather than just the username that was passed by the client. It is turned off by default.

AuthLDAPSearchAsUserDirective

When set, andmod_authnz_ldap has authenticated the user, LDAP searches for authorization use the queried distinguished name (DN) and HTTP basic authentication password of the authenticated user instead of the servers configured credentials.

Theldap-filter andldap-dn authorization checks use searches.

This directive only has effect on the comparisons performed during nested group processing when AuthLDAPCompareAsUser is also enabled.

This directive should only be used when your LDAP server doesn't accept anonymous searches and you cannot use a dedicatedAuthLDAPBindDN.

See also

• AuthLDAPInitialBindAsUser
• AuthLDAPCompareAsUser

AuthLDAPSubGroupAttributeDirective

An LDAP group object may contain members that are users and members that are groups (called nested or sub groups). TheAuthLDAPSubGroupAttribute directive identifies the labels of group members and theAuthLDAPGroupAttribute directive identifies the labels of the user members. Multiple attributes can be used by specifying this directive multiple times. If not specified, thenmod_authnz_ldap uses themember anduniqueMember attributes.

AuthLDAPSubGroupClassDirective

An LDAP group object may contain members that are users and members that are groups (called nested or sub groups). TheAuthLDAPSubGroupAttribute directive identifies the labels of members that may be sub-groups of the current group (as opposed to user members). TheAuthLDAPSubGroupClass directive specifies the LDAP objectClass values used in verifying that these potential sub-groups are in fact group objects. Verified sub-groups can then be searched for more user or sub-group members. Multiple attributes can be used by specifying this directive multiple times. If not specified, thenmod_authnz_ldap uses thegroupOfNames andgroupOfUniqueNames values.

AuthLDAPURLDirective

An RFC 2255 URL which specifies the LDAP search parameters to use. The syntax of the URL is

If you want to specify more than one LDAP URL that Apache should try in turn, the syntax is:

AuthLDAPURL "ldap://ldap1.example.com ldap2.example.com/dc=..."

Caveat:If you specify multiple servers, you need to enclose the entire URL string in quotes;otherwise you will get an error: "AuthLDAPURL takes one argument, URL to define LDAP connection.."You can of course use search parameters on each of these.

ldap

For regular ldap, use the stringldap. For secure LDAP, useldaps instead. Secure LDAP is only available if Apache was linked to an LDAP library with SSL support.

host:port

The name/port of the ldap server (defaults tolocalhost:389 forldap, andlocalhost:636 forldaps). To specify multiple, redundant LDAP servers, just list all servers, separated by spaces.mod_authnz_ldap will try connecting to each server in turn, until it makes a successful connection. If multiple ldap servers are specified, then entire LDAP URL must be encapsulated in double quotes.

Once a connection has been made to a server, that connection remains active for the life of thehttpd process, or until the LDAP server goes down.

If the LDAP server goes down and breaks an existing connection,mod_authnz_ldap will attempt to re-connect, starting with the primary server, and trying each redundant server in turn. Note that this is different than a true round-robin search.

basedn

The DN of the branch of the directory where all searches should start from. At the very least, this must be the top of your directory tree, but could also specify a subtree in the directory.

attribute

The attribute to search for. Although RFC 2255 allows a comma-separated list of attributes, only the first attribute will be used, no matter how many are provided. If no attributes are provided, the default is to useuid. It's a good idea to choose an attribute that will be unique across all entries in the subtree you will be using. All attributes listed will be put into the environment with an AUTHENTICATE_ prefix for use by other modules.

scope

The scope of the search. Can be eitherone orsub. Note that a scope ofbase is also supported by RFC 2255, but is not supported by this module. If the scope is not provided, or ifbase scope is specified, the default is to use a scope ofsub.

filter

A valid LDAP search filter. If not provided, defaults to(objectClass=*), which will search for all objects in the tree. Filters are limited to approximately 8000 characters (the definition ofMAX_STRING_LEN in the Apache source code). This should be more than sufficient for any application. In 2.4.10 and later, the keywordnone disables the use of a filter; this is required by some primitive LDAP servers.

When doing searches, the attribute, filter and username passed by the HTTP client are combined to create a search filter that looks like(&(filter)(attribute=username)).

For example, consider an URL ofldap://ldap.example.com/o=Example?cn?sub?(posixid=*). When a client attempts to connect using a username ofBabs Jenson, the resulting search filter will be(&(posixid=*)(cn=Babs Jenson)).

An optional parameter can be added to allow the LDAP Url to override the connection type. This parameter can be one of the following:

NONE

Establish an unsecure connection on the default LDAP port. This is the same asldap:// on port 389.

SSL

Establish a secure connection on the default secure LDAP port. This is the same asldaps://

TLS | STARTTLS

Establish an upgraded secure connection on the default LDAP port. This connection will be initiated on port 389 by default and then upgraded to a secure connection on the same port.

See above for examples ofAuthLDAPURL URLs.