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NAME | SYNOPSIS | DESCRIPTION | SYNTAX | OPTIONS | SASL OPTIONS | GSSAPI OPTIONS | TLS OPTIONS | ENVIRONMENT VARIABLES | FILES | SEE ALSO | AUTHOR | ACKNOWLEDGEMENTS | COLOPHON |
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LDAP.CONF(5) File Formats Manual LDAP.CONF(5)
ldap.conf, .ldaprc - LDAP configuration file/environment variables
ETCDIR/ldap.conf, ldaprc, .ldaprc, $LDAP<option-name>
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 current
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 absolute 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 ETCDIR/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.
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.
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.
REFHOPLIMIT <integer>
Specified the maximum number of referrals to follow when
performing a request. The number should be a positive
integer. The default is 5.
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
unlimited 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.
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 implies 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.
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
default is off.
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
support. 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 certificate 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 immediately 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.
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
ETCDIR/ldap.conf
system-wide ldap configuration file
$HOME/ldaprc, $HOME/.ldaprc
user ldap configuration file
$CWD/ldaprc
local ldap configuration file
ldap(3), ldap_set_option(3), ldap_result(3), openssl(1), sasl(3)
Kurt Zeilenga, The OpenLDAP Project
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.CONF(5)
Pages that refer to this page: ldapcompare(1), ldapdelete(1), ldapexop(1), ldapmodify(1), ldapmodrdn(1), ldappasswd(1), ldapsearch(1), ldapvc(1), ldapwhoami(1), ldap(3), ldap_sync(3), slapd.conf(5), slapd-config(5), slapd-meta(5)
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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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