pam_ldap

pam_ldap(5)                   File Formats Manual                  pam_ldap(5)



NAME
       pam_ldap - LDAP pluggable authentication module

DESCRIPTION
       The pam_ldap module is a Pluggable Authentication Module (PAM) which
       provides for authentication, authorization and password changing
       against LDAP servers.

       Features of the PADL pam_ldap module include support for transport
       layer security, SASL authentication, directory server-enforced password
       policy, and host- and group- based logon authorization.

       The present version of pam_ldap supports AIX 5L, FreeBSD 3.x and above,
       HP-UX 11i, IRIX 6.x, Linux, Mac OS X 10.2 and above, and Solaris 2.6
       and above. Many vendors provide their own LDAP authentication
       providers, often also called pam_ldap.  This manual page applies to the
       PADL pam_ldap module only. If you are using a vendor provided module,
       consult the relevant documentation instead.

       When authenticating or authorizing a user, pam_ldap first maps the
       user's login name to a distinguished name by searching the directory
       server. This must be possible using the local system's identity,
       specified in ldap.conf. (Note that presently only simple authentication
       is supported for authenticating in this initial step.)

       To authenticate a user, pam_ldap attempts to bind to the directory
       server using the distinguished name of the user (retrieved previously).
       Both simple and SASL authentication mechanisms are supported; in the
       former case, one should take care to use transport security to prevent
       the user's password being transmitted in the clear.

       A variety of authorization primitives are supported by pam_ldap,
       discussed in the configuration section below.

       Finally, pam_ldap supports a number of password change protocols used
       by directory servers from various vendors. (Some directory servers
       support more than one password change protocol.)

       Whilst pam_ldap is generally configured in the system LDAP naming
       configuration file (ldap.conf), some options can be configured in the
       PAM configuration file, to allow for per-service granularity. These
       options include the path to the LDAP naming configuration file to use,
       so in effect all options can be configured on a per-service basis.
       Options are listed below under PAM Configuration.

CONFIGURATION
       pam_ldap stores its configuration in the ldap.conf file. (It should be
       noted that some LDAP client libraries, such as OpenLDAP, also use a
       configuration file of the same name.  pam_ldap supports many of the
       same configuration file options as OpenLDAP, but it adds several that
       are specific to the functionality it provides.  It is not guaranteed
       that pam_ldap will continue to match the configuration file semantics
       of OpenLDAP.  You may wish to use different files.)

       Configuration file options consist of a keyword followed by a space and
       any arguments. The following options are supported by both pam_ldap and
       the PADL nss_ldap module:

       host <name:port ...>
              Specifies the name(s) or IP address(es) of the LDAP server(s) to
              connect to. In the case that nss_ldap is used for host name
              resolution, each server should be specified as an IP address or
              name that can be resolved without using LDAP.  Multiple servers
              may be specified, each separated by a space.  The failover time
              depends on whether the LDAP client library supports configurable
              network or connect timeouts (see bind_timelimit below).

       base <base>
              Specifies the default base distinguished name (DN) to use for
              searches.

       uri <ldap[is]://[name[:port]] ...>
              For LDAP client libraries that support it, specifies the URI(s)
              of the LDAP server(s) to connect to. The URI scheme may be ldap,
              ldapi, or ldaps, specifying LDAP over TCP, IPC and SSL
              respectively. If applicable, a port number can be specified; the
              default port number for the selected protocol is used if
              omitted. This option takes precedence over the host option; it
              is not possible to combine the two.

       ldap_version <version>
              Specifies the version of the LDAP protocol to use. Presently
              version must be 2 or 3. The default is to use the maximum
              version supported by the client library.

       binddn <binddn>
              Specifies the distinguished name with which to bind to the
              directory server(s). This option is optional; the default is to
              bind anonymously.

       bindpw <bindpw>
              Specifies the cleartext credentials with which to bind. This
              option is only applicable when used with binddn above. The
              default is no credential (anonymous bind). When binding to the
              directory using SASL or other authentication mechanisms apart
              from simple binds, this option is not used.

       rootbinddn <binddn>
              This option has the same syntax and effect as the binddn option
              above, except it applies when the effective user ID is zero. If
              not specified, then the identity specified in binddn is used
              instead. Because the configuration file may be readable by many
              users, the root bind DN credentials are stored in the
              ldap.secret file instead. This file is usually in the same
              directory as the configuration file.

       port <port>
              Specifies the port to connect to; this option is used with the
              host option, and is ignored with the uri option.

       scope <sub|one|base>
              Specifies the search scope (subtree, one level or base object).
              The default scope is subtree; base scope is almost never useful
              for nameservice lookups.

       deref <never|searching|finding|always>
              Specifies the policy for dereferencing aliases. The default
              policy is to never dereference aliases.

       timelimit <timelimit>
              Specifies the time limit (in seconds) to use when performing
              searches. A value of zero (0), which is the default, is to wait
              indefinitely for searches to be completed.

       bind_timelimit <timelimit>
              Specifies the time limit (in seconds) to use when connecting to
              the directory server. This is distinct from the time limit
              specified in timelimit and affects the initial server connection
              only. (Server connections are otherwise cached.) Only some LDAP
              client libraries have the underlying functionality necessary to
              support this option. The default bind timelimit is 30 seconds.

       referrals <yes|no>
              Specifies whether automatic referral chasing should be enabled.
              The default behaviour is specifed by the LDAP client library.

       restart <yes|no>
              Specifies whether the LDAP client library should restart the
              select(2) system call when interrupted. This feature is not
              supported by all client libraries.

       logdir <directory>
              Specifies the directory used for logging by the LDAP client
              library. This feature is not supported by all client libraries.

       debug <level>
              Specifies the debug level used for logging by the LDAP client
              library. This feature is not supported by all client libraries,
              and does not apply to the nss_ldap and pam_ldap modules
              themselves (debugging, if any, is configured separately and
              usually at compile time).

       ssl <on|off|start_tls>
              Specifies whether to use SSL/TLS or not (the default is not to).
              If start_tls is specified then StartTLS is used rather than raw
              LDAP over SSL.  Not all LDAP client libraries support both SSL
              and StartTLS, and all related configuration options.

       sslpath <cert7_path>
              For the Netscape and Mozilla LDAP client libraries only, this
              specifies the path to the X.509 certificate database.

       tls_checkpeer <yes|no>
              Specifies whether to require and verify the server certificate
              or not, when using SSL/TLS with the OpenLDAP client library.
              The default is to use the default behaviour of the client
              library; for OpenLDAP 2.0 and earlier it is "no", for OpenLDAP
              2.1 and later it is "yes". At least one of tls_cacertdir and
              tls_cacertfile is required if peer verification is enabled.

       tls_cacertdir <certificate_dir>
              Specifies the directory containing X.509 certificates for peer
              authentication.

       tls_cacertfile <certificate_file>
              Specifies the path to the X.509 certificate for peer
              authentication.

       tls_randfile <entropy_file>
              Specifies the path to an entropy source.

       tls_ciphers <ciphers>
              Specifies the ciphers to use for TLS. See your TLS
              implementation's documentation for further information.

       tls_cert <certificate_file>
              Specifies the path to the file containing the local certificate
              for client TLS authentication.

       tls_key <key_file>
              Specifies the path to the file containing the private key for
              client TLS authentication.

       The following configuration options apply to pam_ldap only:

       pam_login_attribute <attribute>
              Specifies the attribute to use when constructing the attribute
              value assertion for retrieving a directory entry for a user's
              login name.  The default is "uid", for compatibility with RFC
              2307.

       pam_filter <filter>
              Specifies a filter to use when retrieving user information. The
              user entry must match the attribute value assertion of
              (pam_login_attribute=login_name) as well as any filter specified
              here. There is no default for this option.

       pam_lookup_policy <yes|no>
              Specifies whether to search the root DSE for password policy.
              The default is "no".

       pam_check_host_attr <yes|no>
              Specifies whether the "host" attribute should be checked for
              logon authorization ("account" in the PAM stack). The default is
              not to.  If set to "yes" and a user has no value for the "host"
              attribute, then the user will be unable to login.

       pam_check_service_attr <yes|no>
              Specifies whether the "authorizedService" attribute should be
              checked for logon authorization ("account" in the PAM stack).
              The default is not to. If set to "yes" and a user has no value
              for the "authorizedService" attribute, then the user will be
              unable to login.

       pam_groupdn <groupdn>
              Specifies the distinguished name of a group to which a user must
              belong for logon authorization to succeed.  pam_member_attribute
              <attribute> Specifies the attribute to use when testing a user's
              membership of a group specified in the pam_groupdn option.

       pam_min_uid <uid>
              If specified, a user must have a POSIX user ID of at least uid
              in order for logon authorization to succeed.

       pam_max_uid <uid>
              If specified, a user must have a POSIX user ID of no greater
              than uid in order for logon authorization to succeed.

       pam_template_login_attribute <attribute>
              When using template users (not supported by all PAM
              applications), specifies the attribute containing the user's
              actual login name.  The pam_ldap module will set PAM_USER to the
              value of this attribute if present in the user's entry,
              otherwise it defaults to the user specified in the
              pam_template_login option.

       pam_template_login <user>
              When using template users (not supported by all PAM
              applications), pam_ldap will set PAM_USER to the value of this
              option if the user does not contain a template login attribute.

       pam_password <protocol>
              Specifies the password change protocol to use. The following
              protocols are supported:

              clear  Change password using an LDAPModify request, replacing
                     the userPassword value with the new cleartext password.

              clear_remove_old
                     Change password using an LDAPModify request, first
                     removing the userPassword value containing the old
                     cleartext password, and then adding the userPassword
                     value with the new cleartext password. This protocol is
                     necessary for use with Novell NDS and IBM RACF.

              crypt  Change password using an LDAPModify request, first
                     generating a one way hash of the new password using
                     crypt(3) and then replacing userPassword value with the
                     new hashed password.

              md5    Change password using an LDAPModify request, first
                     generating a one way hash of the new password using MD5
                     and then replacing userPassword value with the new hashed
                     password.

              nds    This is an alias for clear_remove_old.

              racf   This is an alias for clear_remove_old.

              ad     Change password using an LDAPModify request, using the
                     Active Directory Services Interface (ADSI) password
                     change protocol.

              exop   Change password using the RFC 3062 password modify
                     extended operation (only the new password is sent).

              exop_send_old
                     Change password using the RFC 3062 password modify
                     extended operation (both the old and new passwords are
                     sent).

       pam_password_prohibit_message <message>
              Specifies a message to send to users indicating that passwords
              cannot be changed. This could be used to redirect users to
              another means of changing passwords.

       pam_sasl_mech <mechanism>
              Specifies the SASL mechanism to use for PAM authentication. This
              requires SASL libraries be installed. Support for this
              functionality presently experimental and does not support
              password policy controls.

PAM CONFIGURATION
       It is possible to configure some aspects of pam_ldap on a per-service
       basis, in the PAM configuration file (this is usually /etc/pam.conf;
       for PAM implementations based on Linux-PAM, per-service files in
       /etc/pam.d are also supported).

       The following options may be specified as arguments to the pam_ldap
       module:

       config=<path>
              Specifies that pam_ldap should use the configuration file in
              path instead of ldap.conf to retrieve its global configuration.
              Configuring multiple instances of pam_ldap for the same service
              with different configuration files is not supported, because the
              configuration information is cached.

       use_first_pass
              Specifies that pam_ldap should always use the first password
              provided in the authentication stack.

       try_first_pass
              Specifies that pam_ldap should first try the first password
              provided in the authentication stack, and then prompt the user
              for their LDAP password if authentication fails.

       ignore_unknown_user
              Specifies that pam_ldap should return PAM_IGNORE for users that
              are not present in LDAP.  This forces the PAM framework to
              ignore the pam_ldap module. This option is useful where certain
              accounts do not reside in LDAP, but one wishes to make pam_ldap
              "required" for all accounts in the directory. In this case one
              would make both pam_ldap and the other module (for example,
              pam_unix) "required" and enable the ignore_unknown_user option.
              (For this to work, the other module must behave similarly for
              users in the directory; in the case of a module such as pam_unix
              that uses the system accounts database, using nss_ldap(5) should
              be sufficient to meet this requirement.)

       ignore_authinfo_unavail
              Specifies that pam_ldap should return PAM_IGNORE if it cannot
              contact the LDAP server. This option forces the PAM framework to
              ignore the pam_ldap module in this case.

       no_warn
              Specifies that warning messages should not be propagated to the
              PAM application.

       use_authtok
              Analogous to use_first_pass for password changing only.

       debug  This option is recognized by pam_ldap but is presently ignored.

AUTHOR
       The pam_ldap module was developed by PADL Software Pty Ltd
       (www.padl.com).

FILES
       /etc/ldap.conf, /etc/ldap.secret, /etc/pam.conf

SEE ALSO
       pam(8)



                                                                   pam_ldap(5)