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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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LLOADD.CONF(5) File Formats Manual LLOADD.CONF(5)
lloadd.conf - configuration file for lloadd, the stand-alone LDAP
daemon
ETCDIR/lloadd.conf
The file ETCDIR/lloadd.conf contains configuration information for
the lloadd(8)daemon.
The lloadd.conf file consists of a series of global configuration
options that apply to lloadd as a whole (including all backends),
followed by zero or more backend definitions that contain
information specific how a backend instance should be contacted.
The configuration options are case-insensitive; their value, on a
case by case basis, may be case-sensitive.
The general format of lloadd.conf is as follows:
# comment - these options apply to the server as a whole
<global configuration options>
# first backend definition
backend-server <backend 1 definition>
# subsequent backend definitions
...
As many backend servers may be configured as desired.
If a line begins with white space, it is considered a continuation
of the previous line. No physical line should be over 2000 bytes
long.
Blank lines and comment lines beginning with a `#' character are
ignored. Note: continuation lines are unwrapped before comment
processing is applied.
Arguments on configuration lines are separated by white space. If
an argument contains white space, the argument should be enclosed
in double quotes. If an argument contains a double quote (`"') or
a backslash character (`\'), the character should be preceded by a
backslash character.
The specific configuration options available are discussed below
in the Global Configuration Options and General Backend Options.
Refer to the "OpenLDAP Administrator's Guide" for more details on
the lloadd configuration file.
Note that when lloadd is configured as a slapd module, any option
that shares the same name as an option in slapd.conf(5), the slapd
interpretation wins and the lloadd option mentioned is unavailable
through slapd.conf(5) directly, instead, it would have to be
configured via a dedicated attribute in cn=config. In particular,
unless the TLSShareSlapdCTX option is set, lloadd keeps its own
TLS context which cannot be configured except through the dynamic
configuration.
An additional option is available when running as a slapd module:
listen <listen URIs>
The URIs the Load Balancer module should listen on. Must
not overlap with the ones that slapd uses for its own
listening sockets. The related cn=config attribute is
olcBkLloadListen with each URI provided as a separate
value. No changes to this attribute made after the server
has started up will take effect until it is restarted.
Options described in this section apply to all backends. Arguments
that should be replaced by actual text are shown in brackets <>.
argsfile <filename>
The (absolute) name of a file that will hold the lloadd
server's command line (program name and options).
concurrency <integer>
Specify a desired level of concurrency. Provided to the
underlying thread system as a hint. The default is not to
provide any hint.
feature <feature> [...]
Switch additional features supported by the LDAP Load
Balancer on. Supported features are:
proxyauthz
when proxying an operation, pass the client's
authorized identity using the proxy
authorization control (RFC 4370). No control
is added to the operation if initiated by a
client whose bound identity matches the
identity configured in bindconf (no
normalisation of the DN is attempted).
If SASL binds are issued by clients and this
feature is enabled, backend servers need to
support LDAP Who Am I? extended operation for
the Load Balancer to detect the correct
authorization identity.
include <filename>
Read additional configuration information from the given
file before continuing with the next line of the current
file.
io-threads <integer>
Specify the number of threads to use for the connection
manager. The default is 1 and this is typically adequate
for up to 16 CPU cores. The value should be set to a power
of 2.
If modified after server starts up, a change to this option
will not take effect until the server has been restarted.
logfile <filename>
Specify a file for recording lloadd debug messages. By
default these messages only go to stderr, are not recorded
anywhere else, and are unrelated to messages exposed by the
logfile-format debug | syslog-utc | syslog-localtime
Specify the prefix format for messages written to the
logfile. The debug format is the normal format used for
slapd debug messages, with a timestamp in hexadecimal,
followed by a thread ID. The other options are to use
syslog(3) style prefixes, with timestamps either in UTC or
in the local timezone. The default is debug format.
loglevel configuration parameter. Specifying a logfile
copies messages to both stderr and the logfile.
logfile-only on | off
Specify that debug messages should only go to the
configured logfile, and not to stderr.
logfile-rotate <max> <Mbytes> <hours>
Specify automatic rotation for the configured logfile as
the maximum number of old logfiles to retain, a maximum
size in megabytes to allow a logfile to grow before
rotation, and a maximum age in hours for a logfile to be
used before rotation. The maximum number must be in the
range 1-99. Setting Mbytes or hours to zero disables the
size or age check, respectively. At least one of Mbytes or
hours must be non-zero. By default no automatic rotation
will be performed.
loglevel <integer> [...]
Specify the level at which debugging statements and
operation statistics should be syslogged (currently logged
to the syslogd(8) LOG_LOCAL4 facility). They must be
considered subsystems rather than increasingly verbose log
levels. Some messages with higher priority are logged
regardless of the configured loglevel as soon as any
logging is configured. Log levels are additive, and
available levels are:
1 (0x1 trace) trace function calls
2 (0x2 packets) debug packet handling
4 (0x4 args) heavy trace debugging (function
args)
8 (0x8 conns) connection management
16 (0x10 BER) print out packets sent and
received
64 (0x40 config) configuration file processing
256 (0x100 stats) connections, LDAP operations,
results (recommended)
512 (0x200 stats2) stats log entries sent
32768 (0x8000 none) only messages that get logged
whatever log level is set
The desired log level can be input as a single integer that
combines the (ORed) desired levels, both in decimal or in
hexadecimal notation, as a list of integers (that are ORed
internally), or as a list of the names that are shown
between parentheses, such that
loglevel 513
loglevel 0x201
loglevel 512 1
loglevel 0x200 0x1
loglevel stats trace
are equivalent. The keyword any can be used as a shortcut
to enable logging at all levels (equivalent to -1). The
keyword none, or the equivalent integer representation,
causes those messages that are logged regardless of the
configured loglevel to be logged. In fact, if loglevel is
set to 0, no logging occurs, so at least the none level is
required to have high priority messages logged.
The loglevel defaults to stats. This level should usually
also be included when using other loglevels, to help
analyze the logs.
pidfile <filename>
The (absolute) name of a file that will hold the lloadd
server's process ID (see getpid(2)).
sockbuf_max_incoming_client <integer>
Specify the maximum LDAP PDU size accepted coming from
clients. The default is 262143.
sockbuf_max_incoming_upstream <integer>
Specify the maximum LDAP PDU size accepted coming from
upstream connections. The default is 4194303.
tcp-buffer [listener=<URL>] [{read|write}=]<size>
Specify the size of the TCP buffer. A global value for
both read and write TCP buffers related to any listener is
defined, unless the listener is explicitly specified, or
either the read or write qualifiers are used. See tcp(7)
for details. Note that some OS-es implement automatic TCP
buffer tuning.
threads <integer>
Specify the maximum size of the primary thread pool. The
default is 16; the minimum value is 2.
threadqueues <integer>
Specify the number of work queues to use for the primary
thread pool. The default is 1 and this is typically
adequate for up to 8 CPU cores. The value should not
exceed the number of CPUs in the system.
max_pdus_per_cycle <integer>
If set to 0, PDUs are handled by the I/O threads directly,
otherwise a task is queued to be picked up by the thread
pool. This task will process PDUs from the connection until
there is no more data to be read or this limit is reached
when the I/O thread can pick it up again. Very high values
have a potential to cause some connections to be starved in
a very high-bandwidth environment. The default is 1000.
client_max_pending <integer>
Will cause the load balancer to limit the number unfinished
operations for each client connection. The default is 0,
unlimited.
iotimeout <integer>
Specify the number of milliseconds to wait before forcibly
closing a connection with an outstanding write. This allows
faster recovery from various network hang conditions. An
iotimeout of 0 disables this feature. The default is
10000.
write_coherence <integer>
Specify the number of seconds after a write operation is
finished that lloadd will direct operations exclusively to
the last selected backend. A write operation is anything
not handled internally (certain exops, abandon), except
search, compare and bind operations. Bind operations also
reset this restriction. The default is 0, write operations
do not restrict selection. When negative, the restriction
is not time limited and will persist until the next bind.
restrict_exop <OID> <action>
Tell lloadd that extended operation with a given OID should
be handled in a specific way. OID 1.1 is special, setting
a default (only for operations not handled internally).
The meaning of the <action> argument is the same as in
restrict_control below.
restrict_control <OID> <action>
Tell lloadd that a control with a given OID attached to any
operation should be handled in a specific way according to
the <action> argument. At the moment, only operations
passed intact are inspected in this way, in particular,
controls on bind and extended operations are not checked.
In order of descending priority (the control with highest
priority action wins), this is the action made:
reject operations that carry this control will be
rejected.
connection
once an upstream is selected, every future
operation from this client will be directed
to the same connection. Useful when state is
shared between client and upstream that the
load balancer doesn't track.
backend
like write except this does not time out.
write this is treated like a write operation (see
write_coherence) above.
ignore does not influence restrictions, useful when
changing the global exop default. This is
the default handling for exops/controls not
handled by the load balancer internally.
If lloadd is built with support for Transport Layer Security,
there are more options you can specify.
TLSShareSlapdCTX { on | off }
If set to no (the default), lloadd will use its own TLS
context (needs to be configured via cn=config unless lloadd
is run as a standalone daemon). If enabled, the options for
slapd apply instead, since the slapd's TLS context is used
then.
The following options are available only when compiled as a
standalone daemon. When compiled as a slapd(8) module, the
cn=config equivalents need to be used if a separate TLS context
for the module is needed, otherwise use the TLSShareSlapdCTX
option.
TLSCipherSuite <cipher-suite-spec>
Permits configuring what ciphers will be accepted and the
preference order. <cipher-suite-spec> should be a cipher
specification for the TLS library in use (OpenSSL, GnuTLS,
or Mozilla NSS). This directive is not supported when
using MbedTLS. Example:
OpenSSL:
TLSCipherSuite HIGH:MEDIUM:+SSLv2
GnuTLS:
TLSCiphersuite 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
When using Mozilla NSS, the OpenSSL cipher suite
specifications are used and translated into the format used
internally by Mozilla NSS. There isn't an easy way to list
the cipher suites from the command line. The authoritative
list is in the source code for Mozilla NSS in the file
sslinfo.c in the structure
static const SSLCipherSuiteInfo suiteInfo[]
TLSCACertificateFile <filename>
Specifies the file that contains certificates for all of
the Certificate Authorities that lloadd will recognize.
The certificate for the CA that signed the server
certificate must be included among these certificates. If
the signing CA was not a top-level (root) CA, certificates
for the entire sequence of CA's from the signing CA to the
top-level CA should be present. Multiple certificates are
simply appended to the file; the order is not significant.
TLSCACertificatePath <path>
Specifies the path of a directory that contains Certificate
Authority certificates in separate individual files.
Usually only one of this or the TLSCACertificateFile is
used. This directive is not supported when using GnuTLS.
When using Mozilla NSS, <path> may contain a Mozilla NSS
cert/key database. If <path> contains a Mozilla NSS
cert/key database and CA cert files, OpenLDAP will use the
cert/key database and will ignore the CA cert files.
TLSCertificateFile <filename>
Specifies the file that contains the lloadd server
certificate.
When using Mozilla NSS, if using a cert/key database
(specified with TLSCACertificatePath), TLSCertificateFile
specifies the name of the certificate to use:
TLSCertificateFile Server-Cert
If using a token other than the internal built in token,
specify the token name first, followed by a colon:
TLSCertificateFile my hardware device:Server-Cert
Use certutil -L to list the certificates by name:
certutil -d /path/to/certdbdir -L
TLSCertificateKeyFile <filename>
Specifies the file that contains the lloadd server private
key that matches the certificate stored in the
TLSCertificateFile file. Currently, the private key must
not be protected with a password, so it is of critical
importance that it is protected carefully.
When using Mozilla NSS, TLSCertificateKeyFile specifies the
name of a file that contains the password for the key for
the certificate specified with TLSCertificateFile. The
modutil command can be used to turn off password protection
for the cert/key database. For example, if
TLSCACertificatePath specifies /etc/openldap/certdb as the
location of the cert/key database, use modutil to change
the password to the empty string:
modutil -dbdir /etc/openldap/certdb -changepw 'NSS Certificate DB'
You must have the old password, if any. Ignore the WARNING
about the running browser. Press 'Enter' for the new
password.
TLSDHParamFile <filename>
This directive specifies the file that contains parameters
for Diffie-Hellman ephemeral key exchange. This is
required in order to use a DSA certificate on the server,
or an RSA certificate missing the "key encipherment" key
usage. Note that setting this option may also enable
Anonymous Diffie-Hellman key exchanges in certain non-
default cipher suites. Anonymous key exchanges should
generally be avoided since they provide no actual client or
server authentication and provide no protection against
man-in-the-middle attacks. You should append "!ADH" to
your cipher suites to ensure that these suites are not
used. When using Mozilla NSS these parameters are always
generated randomly so this directive is ignored. This
directive is not supported when using MbedTLS.
TLSECName <name>
Specify the name of a curve to use for Elliptic curve
Diffie-Hellman ephemeral key exchange. This is required to
enable ECDHE algorithms in OpenSSL. This option is not
used with GnuTLS; the curves may be chosen in the GnuTLS
ciphersuite specification. This option is also ignored for
Mozilla NSS.
TLSProtocolMin <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.,
TLSProtocolMin 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 directive is ignored with GnuTLS.
TLSRandFile <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 directive
is ignored with GnuTLS and Mozilla NSS.
TLSVerifyClient <level>
Specifies what checks to perform on client certificates in
an incoming TLS session, if any. The <level> can be
specified as one of the following keywords:
never This is the default. lloadd will not ask the client
for a certificate.
allow The client certificate is requested. If no
certificate is provided, the session proceeds
normally. If a bad certificate is provided, it will
be ignored and the session proceeds normally.
try The client certificate is requested. If no
certificate is provided, the session proceeds
normally. If a bad certificate is provided, the
session is immediately terminated.
demand | hard | true
These keywords are all equivalent, for compatibility
reasons. The client certificate is requested. If
no certificate is provided, or a bad certificate is
provided, the session is immediately terminated.
TLSCRLCheck <level>
Specifies if the Certificate Revocation List (CRL)
of the CA should be used to verify if the client
certificates have not been revoked. This requires
TLSCACertificatePath parameter to be set. This
directive is ignored with GnuTLS and Mozilla NSS.
<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
TLSCRLFile <filename>
Specifies a file containing a Certificate Revocation
List to be used for verifying that certificates have
not been revoked. This directive is only valid when
using GnuTLS and Mozilla NSS.
Options in this section describe how the lloadd connects and
authenticates to the backend servers. Backends are organised in
groups (tiers). Backends in the first tier are tried first, if
none of them are reachable, the following tier is tried in the
same way. If there is a backend in the tier that has suitable
connections, but they are busy, no further tier is consulted. This
is useful in high availability scenarios where a group of servers
(e.g. the local environment) should be contacted if possible.
It is assumed all backend servers serve the same data. On startup,
the configured connections are set up and those not dedicated to
handle bind requests are authenticated with the backend using the
information in the bindconf option. The authentication
configuration is shared between them.
bindconf
[bindmethod=simple|sasl] [binddn=<dn>] [saslmech=<mech>]
[authcid=<identity>] [authzid=<identity>]
[credentials=<passwd>] [realm=<realm>]
[secprops=<properties>] [timeout=<seconds>]
[network-timeout=<seconds>]
[keepalive=<idle>:<probes>:<interval>]
[tcp-user-timeout=<milliseconds>] [tls_cert=<file>]
[tls_key=<file>] [tls_cacert=<file>] [tls_cacertdir=<path>]
[tls_reqcert=never|allow|try|demand]
[tls_cipher_suite=<ciphers>] [tls_crlcheck=none|peer|all]
[tls_protocol_min=<major>[.<minor>]]
Specifies the bind credentials lloadd uses when setting up
its regular connections to all backends.
A bindmethod of simple requires the options binddn and
credentials and should only be used when adequate security
services (e.g. TLS or IPSEC) are in place. REMEMBER:
simple bind credentials must be in cleartext! A bindmethod
of sasl requires the option saslmech. Depending on the
mechanism, an authentication identity and/or credentials
can be specified using authcid and credentials. The
authzid parameter may be used to specify an authorization
identity. Specific security properties (as with the
sasl-secprops keyword above) for a SASL bind can be set
with the secprops option. A non default SASL realm can be
set with the realm option.
The timeout parameter indicates how long an operation can
be pending a response (result, search entry, ...) from the
server in seconds. Due to how timeouts are detected, the
timeout might not be detected and handled up to timeout
seconds after it happens.
The network-timeout parameter sets how long the consumer
will wait to establish a network connection to the
provider. Once a connection is established, the timeout
parameter determines how long the consumer will wait for
the initial Bind request to complete.
Timeout set to 0 means no timeout is in effect and by
default, no timeouts are in effect.
The keepalive parameter sets the values of idle, probes,
and interval used to check whether a socket is alive; idle
is the number of seconds a connection needs to remain idle
before TCP starts sending keepalive probes; probes is the
maximum number of keepalive probes TCP should send before
dropping the connection; interval is interval in seconds
between individual keepalive probes. Only some systems
support the customization of these values; the keepalive
parameter is ignored otherwise, and system-wide settings
are used.
The tcp-user-timeout parameter, if non-zero, corresponds to
the TCP_USER_TIMEOUT set on the upstream connections,
overriding the operating system setting. Only some systems
support the customization of this parameter, it is ignored
otherwise and system-wide settings are used.
tier <tier type>
Groups servers which should be considered in the same try.
If a viable connection is found even if busy, the load
balancer does not proceed to the next tier. The process of
selection a connection within a tier depends on the tier's
type.
Available types are:
roundrobin
Servers are tried in order and if one is selected
successfully, the following search will try from the one
next on the list.
weighted
Backend servers accept a new option weight=<int> which
indicates how often it should be selected. If unspecified,
weight defaults to 0 and such backends have a slight chance
of being selected even when a non-zero weight backend is
configured in the tier. The selection process is along the
lines of RFC2782.
bestof Like with weighted, backends accept the weight=<int>
option. Average latency multiplied by weight is measured
over time. The selection process chooses 2 backends at
random, compares their weighted latencies and the backend
with a better (lower) score is tried. If the backend is not
available (or is busy), the other backend is tried, then
backends are chosen in a round-robin order.
Note that unlike weighted, the higher the weight, the
higher the "effective" latency and lower the chance a
backend is selected.
backend-server
uri=ldap[s]://<hostname>[:port] [retry=<retry interval in
ms>] [starttls=yes|critical] [numconns=<conns>]
[bindconns=<conns>] [max-pending-ops=<ops>] [conn-max-
pending=<ops>]
Marks the beginning of a backend definition.
uri specifies the backend as an LDAP URI. If <port> is not
given, the standard LDAP port number (389 or 636) is used.
Lloadd will attempt to maintain numconns active connections
and also bindconns active connections dedicated to handling
client bind requests.
If an error occurs on a working connection, a new
connection attempt is made immediately, if one happens on
establishing a new connection to this backend, lloadd will
wait before a new reconnect attempt is made according to
the retry parameter (default is 5 seconds).
Operations will be distributed across the backend's
connections (upstreams).
The parameter conn-max-pending unless set to 0 (the
default), will limit the number unfinished operations per
upstream connection. Similarly, max-pending-ops will limit
the total number or unfinished operations across all
backend's connections, 0, the default, means no limit will
be imposed for this backend.
The starttls parameter specifies use of the StartTLS
extended operation to establish a TLS session before
Binding to the provider. If the critical argument is
supplied, the session will be aborted if the StartTLS
request fails. Otherwise the syncrepl session continues
without TLS. The tls_reqcert setting defaults to "demand"
and the other TLS settings default to the same as the main
slapd TLS settings.
Here is a short example of a configuration file:
argsfile LOCALSTATEDIR/run/lloadd.args
pidfile LOCALSTATEDIR/run/lloadd.pid
# cancel not supported yet
restrict_exop 1.3.6.1.1.8 reject
# turn not supported
restrict_exop 1.3.6.1.1.19 reject
# TXN Exop if desired, otherwise reject
restrict_exop 1.3.6.1.1.21.1 connection
# Paged results control
restrict_control 1.2.840.113556.1.4.319 connection
# VLV control
restrict_control 2.16.840.1.113730.3.4.9 connection
bindconf
bindmethod=simple
binddn=cn=test
credentials=pass
tier weighted
backend-server
uri=ldap://ldap1.example.com
numconns=3
bindconns=2
retry=5000
max-pending-ops=5
conn-max-pending=3
weight=5
backend-server
uri=ldap://ldap2.example.com
numconns=3
bindconns=2
retry=5000
max-pending-ops=5
conn-max-pending=3
weight=10
"OpenLDAP Administrator's Guide" contains a longer annotated
example of a configuration file. The original ETCDIR/lloadd.conf
is another example.
Support for proxying SASL Binds is limited to the EXTERNAL
mechanism (and only to extract the DN of a client TLS certificate
if used during the last renegotiation) and mechanisms that rely
neither on connection metadata (as Kerberos does) nor establish a
SASL integrity/confidentialiy layer (again, some Kerberos
mechanisms, DIGEST-MD5 can negotiate this).
ETCDIR/lloadd.conf
default lloadd configuration file
ldap(3), gnutls-cli(1), slapd.conf(5), tcp(7), lloadd(8),
slapd(8).
"OpenLDAP Administrator's Guide"
(http://www.OpenLDAP.org/doc/admin/)
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
[email protected]
OpenLDAP LDVERSION RELEASEDATE LLOADD.CONF(5)
Pages that refer to this page: lloadd(8)
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