# Predefined Constants

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)
  Alias dereferencing rule - Never.
`LDAP_DEREF_SEARCHING` (integer)
  Alias dereferencing rule - Searching.
`LDAP_DEREF_FINDING` (integer)
  Alias dereferencing rule - Finding.
`LDAP_DEREF_ALWAYS` (integer)
  Alias dereferencing rule - Always.
`LDAP_OPT_DEREF` (integer)
  Specifies alternative rules for following aliases at the server.
`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)
  Specifies the number of seconds to wait for search results.

  > 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)
  Option for ldap_set_option() to allow setting network timeout. (Available as of PHP 5.3.0)
`LDAP_OPT_PROTOCOL_VERSION` (integer)
  Specifies the LDAP protocol to be used (V2 or V3).
`LDAP_OPT_ERROR_NUMBER` (integer)
  Latest session error number.
`LDAP_OPT_REFERRALS` (integer)
  Specifies whether to automatically follow referrals returned by the LDAP server.
`LDAP_OPT_RESTART` (integer)
  Determines whether or not the connection should be implicitly restarted.
`LDAP_OPT_HOST_NAME` (integer)
  Sets/gets a space-separated of hosts when trying to connect.
`LDAP_OPT_ERROR_STRING` (integer)
  Alias of `LDAP_OPT_DIAGNOSTIC_MESSAGE`.
`LDAP_OPT_DIAGNOSTIC_MESSAGE` (integer)
  Gets the latest session error message.
`LDAP_OPT_MATCHED_DN` (integer)
  Sets/gets the matched DN associated with the connection.
`LDAP_OPT_SERVER_CONTROLS` (integer)
  Specifies a default list of server controls to be sent with each request.
`LDAP_OPT_CLIENT_CONTROLS` (integer)
  Specifies a default list of client controls to be processed with each request.
`LDAP_OPT_DEBUG_LEVEL` (integer)
  Specifies a bitwise level for debug traces.
`LDAP_OPT_X_KEEPALIVE_IDLE` (integer)
  Specifies the number of seconds a connection needs to remain idle before TCP starts sending keepalive probes.
`LDAP_OPT_X_KEEPALIVE_PROBES` (integer)
  Specifies the maximum number of keepalive probes TCP should send before dropping the connection.
`LDAP_OPT_X_KEEPALIVE_INTERVAL` (integer)
  Specifies the interval in seconds between individual keepalive probes.
`LDAP_OPT_X_TLS_CACERTDIR` (string)
  Specifies the path of the directory containing CA certificates.
`LDAP_OPT_X_TLS_CACERTFILE` (string)
  Specifies the full-path of the CA certificate file.
`LDAP_OPT_X_TLS_CERTFILE` (string)
  Specifies the full-path of the certificate file.
`LDAP_OPT_X_TLS_CIPHER_SUITE` (string)
  Specifies the allowed cipher suite.
`LDAP_OPT_X_TLS_CRLCHECK` (integer)
  Specifies the CRL evaluation strategy. This must be one of: `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)
  Specifies the full-path of the CRL file.

  > Note: This option is only valid for GnuTLS.

`LDAP_OPT_X_TLS_DHFILE` (string)
  Specifies the full-path of the file containing the parameters for Diffie-Hellman ephemeral key exchange.

  > Note: This option is ignored by GnuTLS and Mozilla NSS.

`LDAP_OPT_X_TLS_KEYFILE` (string)
  Specifies the full-path of the certificate key file.
`LDAP_OPT_X_TLS_PROTOCOL_MIN` (integer)
  Specifies the minimum protocol version. This can be one of: `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)
  Sets/gets the random file when one of the system default ones are not available.
`LDAP_OPT_X_TLS_REQUIRE_CERT` (integer)
  Specifies the certificate checking checking strategy. This must be one of: `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)
  SSL Authentication Mode - No authentication required. (Only for Oracle LDAP)
`GSLC_SSL_ONEWAY_AUTH` (integer)
  SSL Authentication Mode - Only server authentication required. (Only for Oracle LDAP)
`GSLC_SSL_TWOWAY_AUTH` (integer)
  SSL Authentication Mode - Both server and client authentication required. (Only for Oracle LDAP)
`LDAP_EXOP_START_TLS` (string)
  Extended Operation constant - Start TLS (» RFC 4511).
`LDAP_EXOP_MODIFY_PASSWD` (string)
  Extended Operation constant - Modify password (» RFC 3062).
`LDAP_EXOP_REFRESH` (string)
  Extended Operation Constant - Refresh (» RFC 2589).
`LDAP_EXOP_WHO_AM_I` (string)
  Extended Operation Constant - WHOAMI (» RFC 4532).
`LDAP_EXOP_TURN` (string)
  Extended Operation Constant - Turn (» RFC 4531).
`LDAP_CONTROL_MANAGEDSAIT` (string)
  Control Constant - Manage DSA IT (» RFC 3296). Available as of PHP 7.3.0.
`LDAP_CONTROL_PROXY_AUTHZ` (string)
  Control Constant - Proxied Authorization (» RFC 4370). Available as of PHP 7.3.0.
`LDAP_CONTROL_SUBENTRIES` (string)
  Control Constant - Subentries (» RFC 3672). Available as of PHP 7.3.0.
`LDAP_CONTROL_VALUESRETURNFILTER` (string)
  Control Constant - Filter returned values (» RFC 3876). Available as of PHP 7.3.0.
`LDAP_CONTROL_ASSERT` (string)
  Control Constant - Assertion (» RFC 4528). Available as of PHP 7.3.0.
`LDAP_CONTROL_PRE_READ` (string)
  Control Constant - Pre read (» RFC 4527). Available as of PHP 7.3.0.
`LDAP_CONTROL_POST_READ` (string)
  Control Constant - Post read (» RFC 4527). Available as of PHP 7.3.0.
`LDAP_CONTROL_SORTREQUEST` (string)
  Control Constant - Sort request (» RFC 2891). Available as of PHP 7.3.0.
`LDAP_CONTROL_SORTRESPONSE` (string)
  Control Constant - Sort response (» RFC 2891). Available as of PHP 7.3.0.
`LDAP_CONTROL_PAGEDRESULTS` (string)
  Control Constant - Paged results (» RFC 2696). Available as of PHP 7.3.0.
`LDAP_CONTROL_AUTHZID_REQUEST` (string)
  Control Constant - Authorization Identity Request (» RFC 3829). Available as of PHP 7.3.0.
`LDAP_CONTROL_AUTHZID_RESPONSE` (string)
  Control Constant - Authorization Identity Response (» RFC 3829). Available as of PHP 7.3.0.
`LDAP_CONTROL_SYNC` (string)
  Control Constant - Content Synchronization Operation (» RFC 4533). Available as of PHP 7.3.0.
`LDAP_CONTROL_SYNC_STATE` (string)
  Control Constant - Content Synchronization Operation State (» RFC 4533). Available as of PHP 7.3.0.
`LDAP_CONTROL_SYNC_DONE` (string)
  Control Constant - Content Synchronization Operation Done (» RFC 4533). Available as of PHP 7.3.0.
`LDAP_CONTROL_DONTUSECOPY` (string)
  Control Constant - Don't Use Copy (» RFC 6171). Available as of PHP 7.3.0.
`LDAP_CONTROL_PASSWORDPOLICYREQUEST` (string)
  Control Constant - Password Policy Request. Available as of PHP 7.3.0.
`LDAP_CONTROL_PASSWORDPOLICYRESPONSE` (string)
  Control Constant - Password Policy Response. Available as of PHP 7.3.0.
`LDAP_CONTROL_X_INCREMENTAL_VALUES` (string)
  Control Constant - Active Directory Incremental Values. Available as of PHP 7.3.0.
`LDAP_CONTROL_X_DOMAIN_SCOPE` (string)
  Control Constant - Active Directory Domain Scope. Available as of PHP 7.3.0.
`LDAP_CONTROL_X_PERMISSIVE_MODIFY` (string)
  Control Constant - Active Directory Permissive Modify. Available as of PHP 7.3.0.
`LDAP_CONTROL_X_SEARCH_OPTIONS` (string)
  Control Constant - Active Directory Search Options. Available as of PHP 7.3.0.
`LDAP_CONTROL_X_TREE_DELETE` (string)
  Control Constant - Active Directory Tree Delete. Available as of PHP 7.3.0.
`LDAP_CONTROL_X_EXTENDED_DN` (string)
  Control Constant - Active Directory Extended DN. Available as of PHP 7.3.0.
`LDAP_CONTROL_VLVREQUEST` (string)
  Control Constant - Virtual List View Request. Available as of PHP 7.3.0.
`LDAP_CONTROL_VLVRESPONSE` (string)
  Control Constant - Virtual List View Response. Available as of PHP 7.3.0.