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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | SIMPLE AUTHENTICATION | GENERAL AUTHENTICATION | SASL AUTHENTICATION | REBINDING | UNBINDING | ERRORS | NOTES | SEE ALSO | ACKNOWLEDGEMENTS | COLOPHON |
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LDAP_BIND(3) Library Functions Manual LDAP_BIND(3)
ldap_bind, ldap_bind_s, ldap_simple_bind, ldap_simple_bind_s,
ldap_sasl_bind, ldap_sasl_bind_s, ldap_sasl_interactive_bind_s,
ldap_parse_sasl_bind_result, ldap_unbind, ldap_unbind_s,
ldap_unbind_ext, ldap_unbind_ext_s, ldap_set_rebind_proc - LDAP
bind routines
OpenLDAP LDAP (libldap, -lldap)
#include <ldap.h>
int ldap_bind(LDAP *ld, const char *who, const char *cred,
int method);
int ldap_bind_s(LDAP *ld, const char *who, const char *cred,
int method);
int ldap_simple_bind(LDAP *ld, const char *who, const char *passwd);
int ldap_simple_bind_s(LDAP *ld, const char *who, const char *passwd);
int ldap_sasl_bind(LDAP *ld, const char *dn, const char *mechanism,
struct berval *cred, LDAPControl *sctrls[],
LDAPControl *cctrls[], int *msgidp);
int ldap_sasl_bind_s(LDAP *ld, const char *dn, const char *mechanism,
struct berval *cred, LDAPControl *sctrls[],
LDAPControl *cctrls[], struct berval **servercredp);
int ldap_parse_sasl_bind_result(LDAP *ld, LDAPMessage *res,
struct berval **servercredp, int freeit);
int ldap_sasl_interactive_bind_s(LDAP *ld, const char *dn,
const char *mechs,
LDAPControl *sctrls[], LDAPControl *cctrls[],
unsigned flags, LDAP_SASL_INTERACT_PROC *interact,
void *defaults);
int ldap_sasl_interactive_bind(LDAP *ld, const char *dn,
const char *mechs,
LDAPControl *sctrls[], LDAPControl *cctrls[],
unsigned flags, LDAP_SASL_INTERACT_PROC *interact,
void *defaults, LDAPMessage *result,
const char **rmechp, int *msgidp);
int (LDAP_SASL_INTERACT_PROC)(LDAP *ld, unsigned flags, void *defaults, void *sasl_interact);
int ldap_unbind(LDAP *ld);
int ldap_unbind_s(LDAP *ld);
int ldap_unbind_ext(LDAP *ld, LDAPControl *sctrls[],
LDAPControl *cctrls[]);
int ldap_unbind_ext_s(LDAP *ld, LDAPControl *sctrls[],
LDAPControl *cctrls[]);
int ldap_set_rebind_proc (LDAP *ld, LDAP_REBIND_PROC *ldap_proc, void *params);
int (LDAP_REBIND_PROC)(LDAP *ld, LDAP_CONST char *url, ber_tag_t request, ber_int_t msgid, void *params);
These routines provide various interfaces to the LDAP bind
operation. After an association with an LDAP server is made using
ldap_init(3), an LDAP bind operation should be performed before
other operations are attempted over the connection. An LDAP bind
is required when using Version 2 of the LDAP protocol; it is
optional for Version 3 but is usually needed due to security
considerations.
There are three types of bind calls, ones providing simple
authentication, ones providing SASL authentication, and general
routines capable of doing either simple or SASL authentication.
SASL (Simple Authentication and Security Layer) can negotiate one
of many different kinds of authentication. Both synchronous and
asynchronous versions of each variant of the bind call are
provided. All routines take ld as their first parameter, as
returned from ldap_init(3).
The simplest form of the bind call is ldap_simple_bind_s(). It
takes the DN to bind as in who, and the userPassword associated
with the entry in passwd. It returns an LDAP error indication
(see ldap_error(3)). The ldap_simple_bind() call is asynchronous,
taking the same parameters but only initiating the bind operation
and returning the message id of the request it sent. The result
of the operation can be obtained by a subsequent call to
ldap_result(3). The ldap_sasl_bind_s() and asynchronous
ldap_sasl_bind() functions can also be used to make a simple bind
by using LDAP_SASL_SIMPLE as the SASL mechanism.
The ldap_bind() and ldap_bind_s() routines can be used when the
authentication method to use needs to be selected at runtime.
They both take an extra method parameter selecting the
authentication method to use. It should be set to
LDAP_AUTH_SIMPLE to select simple authentication. ldap_bind()
returns the message id of the request it initiates. ldap_bind_s()
returns an LDAP error indication.
For SASL binds the server always ignores any provided DN, so the
dn parameter should always be NULL. ldap_sasl_bind_s() sends a
single SASL bind request with the given SASL mechanism and
credentials in the cred parameter. The format of the credentials
depends on the particular SASL mechanism in use. For mechanisms
that provide mutual authentication the server's credentials will
be returned in the servercredp parameter. The routine returns an
LDAP error indication (see ldap_error(3)). The ldap_sasl_bind()
call is asynchronous, taking the same parameters but only sending
the request and returning the message id of the request it sent.
The result of the operation can be obtained by a subsequent call
to ldap_result(3). The result must be additionally parsed by
ldap_parse_sasl_bind_result() to obtain any server credentials
sent from the server.
Any returned server credentials should be freed using
ber_bvfree().
Many SASL mechanisms require multiple message exchanges to perform
a complete authentication. Applications should generally use
ldap_sasl_interactive_bind_s() rather than calling the basic
ldap_sasl_bind() functions directly. The mechs parameter should
contain a space-separated list of candidate mechanisms to use. If
this parameter is NULL or empty the library will query the
supportedSASLMechanisms attribute from the server's rootDSE for
the list of SASL mechanisms the server supports. The flags
parameter controls the interaction used to retrieve any necessary
SASL authentication parameters and should be one of:
LDAP_SASL_AUTOMATIC
use defaults if available, prompt otherwise
LDAP_SASL_INTERACTIVE
always prompt
LDAP_SASL_QUIET
never prompt
The interact function uses the provided defaults to handle
requests from the SASL library for particular authentication
parameters. There is no defined format for the defaults
information; it is up to the caller to use whatever format is
appropriate for the supplied interact function. The sasl_interact
parameter comes from the underlying SASL library. When used with
Cyrus SASL this is an array of sasl_interact_t structures. The
Cyrus SASL library will prompt for a variety of inputs, including:
SASL_CB_GETREALM
the realm for the authentication attempt
SASL_CB_AUTHNAME
the username to authenticate
SASL_CB_PASS
the password for the provided username
SASL_CB_USER
the username to use for proxy authorization
SASL_CB_NOECHOPROMPT
generic prompt for input with input echoing disabled
SASL_CB_ECHOPROMPT
generic prompt for input with input echoing enabled
SASL_CB_LIST_END
indicates the end of the array of prompts
See the Cyrus SASL documentation for more details.
Applications which need to manage connections asynchronously may
use ldap_sasl_interactive_bind() instead of the synchronous
version. A valid mechs parameter must be supplied, otherwise the
library will be forced to query the server for a list of supported
mechanisms, and this query will be performed synchronously. The
other parameters are the same as for the synchronous function,
with three additional parameters. The actual SASL mechanism that
was used, and the message ID for use with ldap_result() will be
returned in rmechp and msgidp, respectively. The value in rmechp
must not be modified by the caller and must be passed back on each
subsequent call. The message obtained from ldap_result() must be
passed in the result parameter. This parameter must be NULL when
initiating a new Bind. The caller must free the result message
after each call using ldap_msgfree(). The
ldap_sasl_interactive_bind() function returns an LDAP result code.
If the code is LDAP_SASL_BIND_IN_PROGRESS then the Bind is not
complete yet, and this function must be called again with the next
result from the server.
The ldap_set_rebind_proc function() sets the process to use for
binding when an operation returns a referral. This function is
used when an application needs to bind to another server in order
to follow a referral or search continuation reference.
The function takes ld, the rebind function, and the params, the
arbitrary data like state information which the client might need
to properly rebind. The LDAP_OPT_REFERRALS option in the ld must
be set to ON for the libraries to use the rebind function. Use the
ldap_set_option function to set the value.
The rebind function parameters are as follows:
The ld parameter must be used by the application when binding to
the referred server if the application wants the libraries to
follow the referral.
The url parameter points to the URL referral string received from
the LDAP server. The LDAP application can use the
ldap_url_parse(3) function to parse the string into its
components.
The request parameter specifies the type of request that generated
the referral.
The msgid parameter specifies the message ID of the request
generating the referral.
The params parameter is the same value as passed originally to the
ldap_set_rebind_proc() function.
The LDAP libraries set all the parameters when they call the
rebind function. The application should not attempt to free either
the ld or the url structures in the rebind function.
The application must supply to the rebind function the required
authentication information such as, user name, password, and
certificates. The rebind function must use a synchronous bind
method.
The ldap_unbind() call is used to unbind from the directory,
terminate the current association, and free the resources
contained in the ld structure. Once it is called, the connection
to the LDAP server is closed, and the ld structure is invalid.
The ldap_unbind_s() call is just another name for ldap_unbind();
both of these calls are synchronous in nature.
The ldap_unbind_ext() and ldap_unbind_ext_s() allows the
operations to specify controls.
Asynchronous routines will return -1 in case of error, setting the
ld_errno parameter of the ld structure. Synchronous routines
return whatever ld_errno is set to. See ldap_error(3) for more
information.
If an anonymous bind is sufficient for the application, the rebind
process need not be provided. The LDAP libraries with the
LDAP_OPT_REFERRALS option set to ON (default value) will
automatically follow referrals using an anonymous bind.
If the application needs stronger authentication than an anonymous
bind, you need to provide a rebind process for that authentication
method. The bind method must be synchronous.
ldap(3), ldap_error(3), ldap_open(3), ldap_set_option(3),
ldap_url_parse(3) RFC 4422 (http://www.rfc-editor.org), Cyrus SASL
(http://asg.web.cmu.edu/sasl/)
OpenLDAP Software is developed and maintained by The OpenLDAP
Project <http://www.openldap.org/>. OpenLDAP Software is derived
from the University of Michigan LDAP 3.3 Release.
This page is part of the OpenLDAP (an open source implementation
of the Lightweight Directory Access Protocol) project.
Information about the project can be found at
⟨http://www.openldap.org/⟩. If you have a bug report for this
manual page, see ⟨http://www.openldap.org/its/⟩. This page was
obtained from the project's upstream Git repository
⟨https://git.openldap.org/openldap/openldap.git⟩ on 2025-08-11.
(At that time, the date of the most recent commit that was found
in the repository was 2025-08-05.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
OpenLDAP LDVERSION RELEASEDATE LDAP_BIND(3)
Pages that refer to this page: ldappasswd(1), ldap(3), ldap_open(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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