The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.
LDAP_DEREF_NEVER 
    (integer)
   LDAP_DEREF_SEARCHING 
    (integer)
   LDAP_DEREF_FINDING 
    (integer)
   LDAP_DEREF_ALWAYS 
    (integer)
   LDAP_OPT_DEREF 
    (integer)
   LDAP_OPT_SIZELIMIT 
    (integer)
   Specifies the maximum number of entries that can be returned on a search operation.
Note: The actual size limit for operations is also bounded by the server's configured maximum number of return entries. The lesser of these two settings is the actual size limit.
LDAP_OPT_TIMELIMIT 
    (integer)
   Note: The actual time limit for operations is also bounded by the server's configured maximum time. The lesser of these two settings is the actual time limit.
LDAP_OPT_NETWORK_TIMEOUT
    (integer)
   LDAP_OPT_PROTOCOL_VERSION 
    (integer)
   LDAP_OPT_ERROR_NUMBER 
    (integer)
   LDAP_OPT_REFERRALS 
    (integer)
   LDAP_OPT_RESTART 
    (integer)
   LDAP_OPT_HOST_NAME 
    (integer)
   LDAP_OPT_ERROR_STRING 
    (integer)
   LDAP_OPT_DIAGNOSTIC_MESSAGE 
    (integer)
   LDAP_OPT_MATCHED_DN 
    (integer)
   LDAP_OPT_SERVER_CONTROLS 
    (integer)
   LDAP_OPT_CLIENT_CONTROLS 
    (integer)
   LDAP_OPT_DEBUG_LEVEL 
    (integer)
   LDAP_OPT_X_KEEPALIVE_IDLE 
    (integer)
   LDAP_OPT_X_KEEPALIVE_PROBES 
    (integer)
   LDAP_OPT_X_KEEPALIVE_INTERVAL 
    (integer)
   LDAP_OPT_X_TLS_CACERTDIR 
    (string)
   LDAP_OPT_X_TLS_CACERTFILE 
    (string)
   LDAP_OPT_X_TLS_CERTFILE 
    (string)
   LDAP_OPT_X_TLS_CIPHER_SUITE 
    (string)
   LDAP_OPT_X_TLS_CRLCHECK 
    (integer)
   LDAP_OPT_X_TLS_CRL_NONE,LDAP_OPT_X_TLS_CRL_PEER, LDAP_OPT_X_TLS_CRL_ALL.
    
    Note: This option is only valid for OpenSSL.
LDAP_OPT_X_TLS_CRLFILE 
    (string)
   Note: This option is only valid for GnuTLS.
LDAP_OPT_X_TLS_DHFILE 
    (string)
   Note: This option is ignored by GnuTLS and Mozilla NSS.
LDAP_OPT_X_TLS_KEYFILE 
    (string)
   LDAP_OPT_X_TLS_PROTOCOL_MIN 
    (integer)
   LDAP_OPT_X_TLS_PROTOCOL_SSL2,LDAP_OPT_X_TLS_PROTOCOL_SSL3, LDAP_OPT_X_TLS_PROTOCOL_TLS1_0, LDAP_OPT_X_TLS_PROTOCOL_TLS1_1, LDAP_OPT_X_TLS_PROTOCOL_TLS1_2
    
   LDAP_OPT_X_TLS_RANDOM_FILE 
    (string)
   LDAP_OPT_X_TLS_REQUIRE_CERT 
    (integer)
   LDAP_OPT_X_TLS_NEVER,LDAP_OPT_X_TLS_HARD, LDAP_OPT_X_TLS_DEMAND,
LDAP_OPT_X_TLS_ALLOW, LDAP_OPT_X_TLS_TRY.
     (Available as of PHP 7.0.0)
    
   GSLC_SSL_NO_AUTH 
    (integer)
   GSLC_SSL_ONEWAY_AUTH 
    (integer)
   GSLC_SSL_TWOWAY_AUTH 
    (integer)