ldap.conf

LDAP.CONF(5) File Formats Manual LDAP.CONF(5)

NAME

   ldap.conf, .ldaprc - LDAP configuration file/environment variables

SYNOPSIS

   /etc/ldap/ldap.conf, ldaprc, .ldaprc, $LDAP<option-name>

DESCRIPTION

   If the environment variable LDAPNOINIT is defined, all defaulting is disabled.

   The ldap.conf configuration file is used to set system-wide defaults to be applied when running ldap clients.

   Users  may create an optional configuration file, ldaprc or .ldaprc, in their home directory which will be used to override the system-wide defaults file.  The file ldaprc in the cur
   rent working directory is also used.

   Additional configuration files can be specified using the LDAPCONF and LDAPRC environment variables.  LDAPCONF may be set to the path of a configuration file.  This path  can  be  ab
   solute or relative to the current working directory.  The LDAPRC, if defined, should be the basename of a file in the current working directory or in the user's home directory.

   Environmental  variables  may  also be used to augment the file based defaults.  The name of the variable is the option name with an added prefix of LDAP.  For example, to define BASE
   via the environment, set the variable LDAPBASE to the desired value.

   Some options are user-only.  Such options are ignored if present in the ldap.conf (or file specified by LDAPCONF).

   Thus the following files and variables are read, in order:
       variable     $LDAPNOINIT, and if that is not set:
       system file  /etc/ldap/ldap.conf,
       user files   $HOME/ldaprc,  $HOME/.ldaprc,  ./ldaprc,
       system file  $LDAPCONF,
       user files   $HOME/$LDAPRC, $HOME/.$LDAPRC, ./$LDAPRC,
       variables    $LDAP<uppercase option name>.
   Settings late in the list override earlier ones.

SYNTAX

   The configuration options are case-insensitive; their value, on a case by case basis, may be case-sensitive.

   Blank lines are ignored.
   Lines beginning with a hash mark (`#') are comments, and ignored.

   Valid lines are made of an option's name (a sequence of non-blanks, conventionally written in uppercase, although not required), followed by a value.  The value starts with the  first
   non-blank  character  after  the option's name, and terminates at the end of the line, or at the last sequence of blanks before the end of the line.  The tokenization of the value, if
   any, is delegated to the handler(s) for that option, if any.  Quoting values that contain blanks may be incorrect, as the quotes would become part of the value.  For example,

        # Wrong - erroneous quotes:
        URI     "ldap:// ldaps://"

        # Right - space-separated list of URIs, without quotes:
        URI     ldap:// ldaps://

        # Right - DN syntax needs quoting for Example, Inc:
        BASE    ou=IT staff,o="Example, Inc",c=US
        # or:
        BASE    ou=IT staff,o=Example\2C Inc,c=US

        # Wrong - comment on same line as option:
        DEREF   never           # Never follow aliases

   A line cannot be longer than LINE_MAX, which should be more than 2000 bytes on all platforms.  There is no mechanism to split a long line on multiple lines, either for  beautification
   or to overcome the above limit.

OPTIONS

   The different configuration options are:

   URI <ldap[si]://[name[:port]] ...>
          Specifies  the URI(s) of an LDAP server(s) to which the LDAP library should connect.  The URI scheme may be any of ldap, ldaps or ldapi, which refer to LDAP over TCP, LDAP over
          SSL (TLS) and LDAP over IPC (UNIX domain sockets), respectively.  Each server's name can be specified as a domain-style name or an IP address literal.  Optionally, the server's
          name can followed by a ':' and the port number the LDAP server is listening on.  If no port number is provided, the default port for the scheme is used (389  for  ldap://,  636
          for  ldaps://).   For  LDAP  over  IPC, name is the name of the socket, and no port is required, nor allowed; note that directory separators must be URL-encoded, like any other
          characters that are special to URLs; so the socket

               /usr/local/var/ldapi

          must be specified as

               ldapi://%2Fusr%2Flocal%2Fvar%2Fldapi

          A space separated list of URIs may be provided.

   BASE <base>
          Specifies the default base DN to use when performing ldap operations.  The base must be specified as a Distinguished Name in LDAP format.

   BINDDN <dn>
          Specifies the default bind DN to use when performing ldap operations.  The bind DN must be specified as a Distinguished Name in LDAP format.  This is a user-only option.

   DEREF <when>
          Specifies how alias dereferencing is done when performing a search. The <when> can be specified as one of the following keywords:

          never  Aliases are never dereferenced. This is the default.

          searching
                 Aliases are dereferenced in subordinates of the base object, but not in locating the base object of the search.

          finding
                 Aliases are only dereferenced when locating the base object of the search.

          always Aliases are dereferenced both in searching and in locating the base object of the search.

   HOST <name[:port] ...>
          Specifies the name(s) of an LDAP server(s) to which the LDAP library should connect.  Each server's name can be specified as a domain-style name or an IP address and optionally
          followed by a ':' and the port number the ldap server is listening on.  A space separated list of hosts may be provided.  HOST is deprecated in favor of URI.

   KEEPALIVE_IDLE
          Sets/gets the number of seconds a connection needs to remain idle before TCP starts sending keepalive probes. Linux only.

   KEEPALIVE_PROBES
          Sets/gets the maximum number of keepalive probes TCP should send before dropping the connection. Linux only.

   KEEPALIVE_INTERVAL
          Sets/gets the interval in seconds between individual keepalive probes.  Linux only.

   NETWORK_TIMEOUT <integer>
          Specifies the timeout (in seconds) after which the poll(2)/select(2) following a connect(2) returns in case of no activity.

   PORT <port>
          Specifies the default port used when connecting to LDAP servers(s).  The port may be specified as a number.  PORT is deprecated in favor of URI.

   REFERRALS <on/true/yes/off/false/no>
          Specifies if the client should automatically follow referrals returned by LDAP servers.  The default is on.  Note that the command line tools ldapsearch(1) &co always  override
          this option.

   SIZELIMIT <integer>
          Specifies  a size limit (number of entries) to use when performing searches.  The number should be a non-negative integer.  SIZELIMIT of zero (0) specifies a request for unlim
          ited search size.  Please note that the server may still apply any server-side limit on the amount of entries that can be returned by a search operation.

   SOCKET_BIND_ADDRESSES <IP>
          Specifies the source bind IP to be used for connecting to target LDAP server.  Multiple IP addresses must be space separated. Only one valid IPv4 address and/or one valid  IPv6
          address are allowed in the list.

   TIMELIMIT <integer>
          Specifies  a time limit (in seconds) to use when performing searches.  The number should be a non-negative integer.  TIMELIMIT of zero (0) specifies unlimited search time to be
          used.  Please note that the server may still apply any server-side limit on the duration of a search operation.

   VERSION {2|3}
          Specifies what version of the LDAP protocol should be used.

   TIMEOUT <integer>
          Specifies a timeout (in seconds) after which calls to synchronous LDAP APIs will abort if no response is received.  Also used for any ldap_result(3) calls where a NULL  timeout
          parameter is supplied.

SASL OPTIONS

   If OpenLDAP is built with Simple Authentication and Security Layer support, there are more options you can specify.

   SASL_MECH <mechanism>
          Specifies the SASL mechanism to use.

   SASL_REALM <realm>
          Specifies the SASL realm.

   SASL_AUTHCID <authcid>
          Specifies the authentication identity.  This is a user-only option.

   SASL_AUTHZID <authcid>
          Specifies the proxy authorization identity.  This is a user-only option.

   SASL_SECPROPS <properties>
          Specifies Cyrus SASL security properties. The <properties> can be specified as a comma-separated list of the following:

          none   (without any other properties) causes the properties defaults ("noanonymous,noplain") to be cleared.

          noplain
                 disables mechanisms susceptible to simple passive attacks.

          noactive
                 disables mechanisms susceptible to active attacks.

          nodict disables mechanisms susceptible to passive dictionary attacks.

          noanonymous
                 disables mechanisms which support anonymous login.

          forwardsec
                 requires forward secrecy between sessions.

          passcred
                 requires mechanisms which pass client credentials (and allows mechanisms which can pass credentials to do so).

          minssf=<factor>
                 specifies  the  minimum acceptable security strength factor as an integer approximate to effective key length used for encryption.  0 (zero) implies no protection, 1 im
                 plies integrity protection only, 128 allows RC4, Blowfish and other similar ciphers, 256 will require modern ciphers.  The default is 0.

          maxssf=<factor>
                 specifies the maximum acceptable security strength factor as an integer (see minssf description).  The default is INT_MAX.

          maxbufsize=<factor>
                 specifies the maximum security layer receive buffer size allowed.  0 disables security layers.  The default is 65536.

   SASL_NOCANON <on/true/yes/off/false/no>
          Do not perform reverse DNS lookups to canonicalize SASL host names. The default is off.

   SASL_CBINDING <none/tls-unique/tls-endpoint>
          The channel-binding type to use, see also LDAP_OPT_X_SASL_CBINDING. The default is none.

GSSAPI OPTIONS

   If OpenLDAP is built with Generic Security Services Application Programming Interface support, there are more options you can specify.

   GSSAPI_SIGN <on/true/yes/off/false/no>
          Specifies if GSSAPI signing (GSS_C_INTEG_FLAG) should be used.  The default is off.

   GSSAPI_ENCRYPT <on/true/yes/off/false/no>
          Specifies if GSSAPI encryption (GSS_C_INTEG_FLAG and GSS_C_CONF_FLAG) should be used. The default is off.

   GSSAPI_ALLOW_REMOTE_PRINCIPAL <on/true/yes/off/false/no>
          Specifies if GSSAPI based authentication should try to form the target principal name out of the ldapServiceName or dnsHostName attribute of the targets RootDSE entry. The  de
          fault is off.

TLS OPTIONS

   If  OpenLDAP is built with Transport Layer Security support, there are more options you can specify.  These options are used when an ldaps:// URI is selected (by default or otherwise)
   or when the application negotiates TLS by issuing the LDAP StartTLS operation.

   TLS_CACERT <filename>
          Specifies the file that contains certificates for all of the Certificate Authorities the client will recognize.

   TLS_CACERTDIR <path>
          Specifies the path of directories that contain Certificate Authority certificates in separate individual files. Multiple directories may be  specified,  separated  by  a  semi-
          colon.  The TLS_CACERT is always used before TLS_CACERTDIR.

   TLS_CERT <filename>
          Specifies the file that contains the client certificate.  This is a user-only option.

   TLS_ECNAME <name>
          Specify  the  name of the curve(s) to use for Elliptic curve Diffie-Hellman ephemeral key exchange.  This option is only used for OpenSSL.  This option is not used with GnuTLS;
          the curves may be chosen in the GnuTLS ciphersuite specification.

   TLS_KEY <filename>
          Specifies the file that contains the private key that matches the certificate stored in the TLS_CERT file. Currently, the private key must not be protected with a password,  so
          it is of critical importance that the key file is protected carefully.  This is a user-only option.

   TLS_CIPHER_SUITE <cipher-suite-spec>
          Specifies acceptable cipher suite and preference order.  <cipher-suite-spec> should be a cipher specification for the TLS library in use (OpenSSL or GnuTLS).  Example:

                 OpenSSL:
                        TLS_CIPHER_SUITE HIGH:MEDIUM:+SSLv2

                 GnuTLS:
                        TLS_CIPHER_SUITE SECURE256:!AES-128-CBC

          To check what ciphers a given spec selects in OpenSSL, use:

               openssl ciphers -v <cipher-suite-spec>

          With GnuTLS the available specs can be found in the manual page of gnutls-cli(1) (see the description of the option --priority).

          In older versions of GnuTLS, where gnutls-cli does not support the option --priority, you can obtain the  more limited  list of ciphers by calling:

               gnutls-cli -l

   TLS_PROTOCOL_MIN <major>[.<minor>]
          Specifies  minimum  SSL/TLS  protocol version that will be negotiated.  If the server doesn't support at least that version, the SSL handshake will fail.  To require TLS 1.x or
          higher, set this option to 3.(x+1), e.g.,

               TLS_PROTOCOL_MIN 3.2

          would require TLS 1.1.  Specifying a minimum that is higher than that supported by the OpenLDAP implementation will result in it requiring the highest level that it  does  sup‐
          port.  This parameter is ignored with GnuTLS.

   TLS_RANDFILE <filename>
          Specifies  the  file  to obtain random bits from when /dev/[u]random is not available. Generally set to the name of the EGD/PRNGD socket.  The environment variable RANDFILE can
          also be used to specify the filename.  This parameter is ignored with GnuTLS.

   TLS_REQCERT <level>
          Specifies what checks to perform on server certificates in a TLS session.  The <level> can be specified as one of the following keywords:

          never  The client will not request or check any server certificate.

          allow  The server certificate is requested. If a bad certificate is provided, it will be ignored and the session proceeds normally.

          try    The server certificate is requested. If a bad certificate is provided, the session is immediately terminated.

          demand | hard
                 These keywords are equivalent and the same as try.  This is the default setting.

   TLS_REQSAN <level>
          Specifies what checks to perform on the subjectAlternativeName (SAN) extensions in a server certificate when validating the certificate name against the specified  hostname  of
          the server. The <level> can be specified as one of the following keywords:

          never  The client will not check any SAN in the certificate.

          allow  The  SAN  is checked against the specified hostname. If a SAN is present but none match the specified hostname, the SANs are ignored and the usual check against the cer‐
                 tificate DN is used.  This is the default setting.

          try    The SAN is checked against the specified hostname. If no SAN is present in the server certificate, the usual check against the certificate  DN  is  used.  If  a  SAN  is
                 present  but  doesn't match the specified hostname, the session is immediately terminated. This setting may be preferred when a mix of certs with and without SANs are in
                 use.

          demand | hard
                 These keywords are equivalent. The SAN is checked against the specified hostname. If no SAN is present in the server certificate, or no SANs match, the session is  imme
                 diately terminated. This setting should be used when only certificates with SANs are in use.

   TLS_CRLCHECK <level>
          Specifies if the Certificate Revocation List (CRL) of the CA should be used to verify if the server certificates have not been revoked. This requires TLS_CACERTDIR parameter to
          be set. This parameter is ignored with GnuTLS.  <level> can be specified as one of the following keywords:

          none   No CRL checks are performed

          peer   Check the CRL of the peer certificate

          all    Check the CRL for a whole certificate chain

   TLS_CRLFILE <filename>
          Specifies the file containing a Certificate Revocation List to be used to verify if the server certificates have not been revoked. This parameter is only supported with GnuTLS.

ENVIRONMENT VARIABLES

   LDAPNOINIT
          disable all defaulting

   LDAPCONF
          path of a configuration file

   LDAPRC basename of ldaprc file in $HOME or $CWD

   LDAP<option-name>
          Set <option-name> as from ldap.conf

FILES

   /etc/ldap/ldap.conf
          system-wide ldap configuration file

   $HOME/ldaprc, $HOME/.ldaprc
          user ldap configuration file

   $CWD/ldaprc
          local ldap configuration file

SEE ALSO

   ldap(3), ldap_set_option(3), ldap_result(3), openssl(1), sasl(3)

AUTHOR

   Kurt Zeilenga, The OpenLDAP Project

ACKNOWLEDGEMENTS

   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.

OpenLDAP 2.6.10+dfsg-1 2025/05/22 LDAP.CONF(5)