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 de-
faults 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 con-
figuration 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 de-
faults. The name of the variable is the option name with an added pre-
fix 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, con-
ventionally 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 se-
quence 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 li-
brary 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 num-
ber 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 charac-
ters 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 opera-
tions. The base must be specified as a Distinguished Name in
LDAP format.
BINDDN <dn>
Specifies the default bind DN to use when performing ldap opera-
tions. 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 key-
words:
never Aliases are never dereferenced. This is the default.
searching
Aliases are dereferenced in subordinates of the base ob-
ject, but not in locating the base object of the search.
finding
Aliases are only dereferenced when locating the base ob-
ject 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 li-
brary 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)/se-
lect(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 dep-
recated in favor of URI.
REFERRALS <on/true/yes/off/false/no>
Specifies if the client should automatically follow referrals re-
turned by LDAP servers. The default is on. Note that the com-
mand 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. SIZE-
LIMIT 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 opera-
tion.
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. TIME-
LIMIT 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 sup-
plied.
SASL OPTIONS
If OpenLDAP is built with Simple Authentication and Security Layer sup-
port, 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 op-
tion.
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 de-
faults ("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 at-
tacks.
noanonymous
disables mechanisms which support anonymous login.
forwardsec
requires forward secrecy between sessions.
passcred
requires mechanisms which pass client credentials (and al-
lows 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 in-
tegrity 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_CBIND-
ING. The default is none.
GSSAPI OPTIONS
If OpenLDAP is built with Generic Security Services Application Program-
ming 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.
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 nego-
tiates TLS by issuing the LDAP StartTLS operation.
TLS_CACERT <filename>
Specifies the file that contains certificates for all of the Cer-
tificate Authorities the client will recognize.
TLS_CACERTDIR <path>
Specifies the path of directories that contain Certificate Au-
thority certificates in separate individual files. Multiple di-
rectories 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 negoti-
ated. 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 certifi-
cate.
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 cer-
tificate 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 certifi-
cate 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 certifi-
cates 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 Uni-
versity of Michigan LDAP 3.3 Release.
OpenLDAP 2.6.10+dfsg-1 2025/05/22 LDAP.CONF(5)
Generated by dwww version 1.16 on Tue Dec 16 04:46:58 CET 2025.