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NAME |LIBRARY |SYNOPSIS |DESCRIPTION |SIMPLE AUTHENTICATION |GENERAL AUTHENTICATION |SASL AUTHENTICATION |REBINDING |UNBINDING |ERRORS |NOTES |SEE ALSO |ACKNOWLEDGEMENTS |COLOPHON | |
LDAP_BIND(3) Library Functions ManualLDAP_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,intmethod);int ldap_bind_s(LDAP *ld, const char *who, const char *cred,intmethod);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, intfreeit);int ldap_sasl_interactive_bind_s(LDAP *ld, const char *dn,const char *mechs,LDAPControl *sctrls[], LDAPControl *cctrls[],unsignedflags, LDAP_SASL_INTERACT_PROC *interact,void *defaults);int ldap_sasl_interactive_bind(LDAP *ld, const char *dn,const char *mechs,LDAPControl *sctrls[], LDAPControl *cctrls[],unsignedflags, LDAP_SASL_INTERACT_PROC *interact,void *defaults, LDAPMessage *result,const char **rmechp, int *msgidp);int (LDAP_SASL_INTERACT_PROC)(LDAP *ld, unsignedflags, 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_trequest, ber_int_tmsgid, void *params);
These routines provide various interfaces to the LDAP bind operation. After an association with an LDAP server is made usingldap_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 takeld as their first parameter, as returned fromldap_init(3).
The simplest form of the bind call isldap_simple_bind_s(). It takes the DN to bind as inwho, and the userPassword associated with the entry inpasswd. It returns an LDAP error indication (seeldap_error(3)). Theldap_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 toldap_result(3). Theldap_sasl_bind_s()and asynchronousldap_sasl_bind()functions can also be used to make a simple bind by using LDAP_SASL_SIMPLE as the SASL mechanism.
Theldap_bind()andldap_bind_s()routines can be used when the authentication method to use needs to be selected at runtime. They both take an extramethod 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 thedn parameter should always be NULL.ldap_sasl_bind_s() sends a single SASL bind request with the given SASLmechanism and credentials in thecred 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 theservercredp parameter. The routine returns an LDAP error indication (seeldap_error(3)). Theldap_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 toldap_result(3). The result must be additionally parsed byldap_parse_sasl_bind_result() to obtain any server credentials sent from the server. Any returned server credentials should be freed usingber_bvfree(). Many SASL mechanisms require multiple message exchanges to perform a complete authentication. Applications should generally useldap_sasl_interactive_bind_s() rather than calling the basicldap_sasl_bind() functions directly. Themechs 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. Theflags 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 Theinteract function uses the provideddefaults to handle requests from the SASL library for particular authentication parameters. There is no defined format for thedefaults information; it is up to the caller to use whatever format is appropriate for the suppliedinteract function. Thesasl_interact parameter comes from the underlying SASL library. When used with Cyrus SASL this is an array ofsasl_interact_tstructures. 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 useldap_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 withldap_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 fromldap_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 usingldap_msgfree(). Theldap_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.
Theldap_set_rebind_procfunction() 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 takesld, therebind function, and theparams, the arbitrary data like state information which the client might need to properly rebind. The LDAP_OPT_REFERRALS option in theld must be set to ON for the libraries to use the rebind function. Use theldap_set_optionfunction to set the value. The rebind function parameters are as follows: Theld parameter must be used by the application when binding to the referred server if the application wants the libraries to follow the referral. Theurl parameter points to the URL referral string received from the LDAP server. The LDAP application can use theldap_url_parse(3) function to parse the string into its components. Therequest parameter specifies the type of request that generated the referral. Themsgid parameter specifies the message ID of the request generating the referral. Theparams parameter is the same value as passed originally to theldap_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.
Theldap_unbind()call is used to unbind from the directory, terminate the current association, and free the resources contained in theld structure. Once it is called, the connection to the LDAP server is closed, and theld structure is invalid. Theldap_unbind_s()call is just another name forldap_unbind(); both of these calls are synchronous in nature. Theldap_unbind_ext()andldap_unbind_ext_s()allows the operations to specify controls.
Asynchronous routines will return -1 in case of error, setting theld_errno parameter of theld structure. Synchronous routines return whateverld_errno is set to. Seeldap_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 Softwareis developed and maintained by The OpenLDAP Project <http://www.openldap.org/>.OpenLDAP Softwareis derived from the University of Michigan LDAP 3.3 Release.
This page is part of theOpenLDAP (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 isnot part of the original manual page), send a mail to man-pages@man7.orgOpenLDAP LDVERSION RELEASEDATELDAP_BIND(3)Pages that refer to this page:ldappasswd(1), ldap(3), ldap_open(3)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |