nslcd.conf(5) System Manager's Manual nslcd.conf(5)NAMEnslcd.conf - configuration file for LDAP nameservice daemon
DESCRIPTION
The nss-pam-ldapd package allows LDAP directory servers to be used as a
primary source of name service information. (Name service information
typically includes users, hosts, groups, and other such data histori‐
cally stored in flat files or NIS.)
The file nslcd.conf contains the configuration information for running
nslcd (see nslcd(8)). The file contains options, one on each line,
defining the way NSS lookups and PAM actions are mapped to LDAP
lookups.
OPTIONS
RUNTIME OPTIONS
threads NUM
Specifies the number of threads to start that can handle
requests and perform LDAP queries. Each thread opens a separate
connection to the LDAP server. The default is to start 5
threads.
uid UID
This specifies the user id with which the daemon should be run.
This can be a numerical id or a symbolic value. If no uid is
specified no attempt to change the user will be made. Note that
you should use values that don't need LDAP to resolve.
gid GID
This specifies the group id with which the daemon should be run.
This can be a numerical id or a symbolic value. If no gid is
specified no attempt to change the group will be made. Note
that you should use values that don't need LDAP to resolve.
GENERAL CONNECTION OPTIONS
uri URI
Specifies the LDAP URI of the server to connect to. The URI
scheme may be ldap, ldapi or ldaps, specifying LDAP over TCP,
ICP or SSL respectively (if supported by the LDAP library).
Alternatively, the value DNS may be used to try to lookup the
server using DNS SRV records. By default the current domain is
used but another domain can be queried by using the DNS:DOMAIN
syntax.
When using the ldapi scheme, %2f should be used to escape
slashes (e.g. ldapi://%2fvar%2frun%2fslapd%2fldapi/), although
most of the time this should not be needed.
This option may be specified multiple times. Normally, only the
first server will be used with the following servers as fall-
back (see bind_timelimit below).
If LDAP lookups are used for host name resolution, any host
names should be specified as an IP address or name that can be
resolved without using LDAP.
ldap_version VERSION
Specifies the version of the LDAP protocol to use. The default
is to use the maximum version supported by the LDAP library.
binddn DN
Specifies the distinguished name with which to bind to the
directory server for lookups. The default is to bind anony‐
mously.
bindpw PASSWORD
Specifies the credentials with which to bind. This option is
only applicable when used with binddn above. If you set this
option you should consider changing the permissions of the
nslcd.conf file to only grant access to the root user.
rootpwmoddn DN
Specifies the distinguished name to use when the root user tries
to modify a user's password using the PAM module.
rootpwmodpw PASSWORD
Specifies the credentials with which to bind if the root user
tries to change a user's password. This option is only applica‐
ble when used with rootpwmoddn above. If this option is not
specified the PAM module prompts the user for this password. If
you set this option you should consider changing the permissions
of the nslcd.conf file to only grant access to the root user.
SASL AUTHENTICATION OPTIONS
sasl_mech MECHANISM
Specifies the SASL mechanism to be used when performing SASL
authentication.
sasl_realm REALM
Specifies the SASL realm to be used when performing SASL authen‐
tication.
sasl_authcid AUTHCID
Specifies the authentication identity to be used when performing
SASL authentication.
sasl_authzid AUTHZID
Specifies the authorization identity to be used when performing
SASL authentication. Must be specified in one of the formats:
dn:<distinguished name> or u:<username>.
sasl_secprops PROPERTIES
Specifies Cyrus SASL security properties. Allowed values are
described in the ldap.conf(5) manual page.
sasl_canonicalize yes|no
Determines whether the LDAP server host name should be canoni‐
calised. If this is set to yes the LDAP library will do a
reverse host name lookup. By default, it is left up to the LDAP
library whether this check is performed or not.
KERBEROS AUTHENTICATION OPTIONS
krb5_ccname NAME
Set the name for the GSS-API Kerberos credentials cache.
SEARCH/MAPPING OPTIONS
base [MAP] DN
Specifies the base distinguished name (DN) to use as search
base. This option may be supplied multiple times and all speci‐
fied bases will be searched.
A global search base may be specified or a MAP-specific one. If
no MAP-specific search bases are defined the global ones are
used.
If, instead of a DN, the value DOMAIN is specified, the host's
DNS domain is used to construct a search base.
If this value is not defined an attempt is made to look it up in
the configured LDAP server. Note that if the LDAP server is
unavailable during start-up nslcd will not start.
scope [MAP] sub[tree]|one[level]|base
Specifies the search scope (subtree, one level or base object).
The default scope is subtree; base scope is almost never useful
for name service lookups.
deref never|searching|finding|always
Specifies the policy for dereferencing aliases. The default
policy is to never dereference aliases.
referrals yes|no
Specifies whether automatic referral chasing should be enabled.
The default behaviour is to chase referrals.
filter MAP FILTER
The FILTER is an LDAP search filter to use for a specific map.
The default filter is a basic search on the objectClass for the
map (e.g. (objectClass=posixAccount)).
map MAP ATTRIBUTE NEWATTRIBUTE
This option allows for custom attributes to be looked up instead
of the default RFC 2307 attributes. The MAP may be one of the
supported maps below. The ATTRIBUTE is the one as used in RFC
2307 (e.g. userPassword, ipProtocolNumber, macAddress, etc.).
The NEWATTRIBUTE may be any attribute as it is available in the
directory.
If the NEWATTRIBUTE is presented in quotes (") it is treated as
an expression which will be evaluated to build up the actual
value used. See the section on attribute mapping expressions
below for more details.
Only some attributes for group, passwd and shadow entries may be
mapped with an expression (because other attributes may be used
in search filters). For group entries only the userPassword
attribute may be mapped with an expression. For passwd entries
the following attributes may be mapped with an expression: user‐
Password, gidNumber, gecos, homeDirectory and loginShell. For
shadow entries the following attributes may be mapped with an
expression: userPassword, shadowLastChange, shadowMin, shadow‐
Max, shadowWarning, shadowInactive, shadowExpire and shadowFlag.
The uidNumber and gidNumber attributes in the passwd and group
maps may be mapped to the objectSid followed by the domain SID
to derive numeric user and group ids from the SID (e.g. object‐
Sid:S-1-5-21-3623811015-3361044348-30300820).
By default all userPassword attributes are mapped to the
unmatchable password ("*") to avoid accidentally leaking pass‐
word information.
TIMING/RECONNECT OPTIONS
bind_timelimit SECONDS
Specifies the time limit (in seconds) to use when connecting to
the directory server. This is distinct from the time limit
specified in timelimit and affects the set-up of the connection
only. Note that not all LDAP client libraries have support for
setting the connection time out. The default bind_timelimit is
10 seconds.
timelimit SECONDS
Specifies the time limit (in seconds) to wait for a response
from the LDAP server. A value of zero (0), which is the
default, is to wait indefinitely for searches to be completed.
idle_timelimit SECONDS
Specifies the period if inactivity (in seconds) after which the
connection to the LDAP server will be closed. The default is
not to time out connections.
reconnect_sleeptime SECONDS
Specifies the number of seconds to sleep when connecting to all
LDAP servers fails. By default 1 second is waited between the
first failure and the first retry.
reconnect_retrytime SECONDS
Specifies the time after which the LDAP server is considered to
be permanently unavailable. Once this time is reached retries
will be done only once per this time period. The default value
is 10 seconds.
Note that the reconnect logic as described above is the mechanism that
is used between nslcd and the LDAP server. The mechanism between the
NSS and PAM client libraries on one end and nslcd on the other is sim‐
pler with a fixed compiled-in time out of a 10 seconds for writing to
nslcd and a time out of 60 seconds for reading answers. nslcd itself
has a read time out of 0.5 seconds and a write time out of 60 seconds.
SSL/TLS OPTIONS
ssl on|off|start_tls
Specifies whether to use SSL/TLS or not (the default is not to).
If start_tls is specified then StartTLS is used rather than raw
LDAP over SSL. Not all LDAP client libraries support both SSL,
StartTLS and all related configuration options.
tls_reqcert never|allow|try|demand|hard
Specifies what checks to perform on a server-supplied certifi‐
cate. The meaning of the values is described in the
ldap.conf(5) manual page. At least one of tls_cacertdir and
tls_cacertfile is required if peer verification is enabled.
tls_cacertdir PATH
Specifies the directory containing X.509 certificates for peer
authentication. This parameter is ignored when using GnuTLS.
On Debian OpenLDAP is linked against GnuTLS.
tls_cacertfile PATH
Specifies the path to the X.509 certificate for peer authentica‐
tion.
tls_randfile PATH
Specifies the path to an entropy source. This parameter is
ignored when using GnuTLS. On Debian OpenLDAP is linked against
GnuTLS.
tls_ciphers CIPHERS
Specifies the ciphers to use for TLS. See your TLS implementa‐
tion's documentation for further information.
tls_cert PATH
Specifies the path to the file containing the local certificate
for client TLS authentication.
tls_key PATH
Specifies the path to the file containing the private key for
client TLS authentication.
OTHER OPTIONS
pagesize NUMBER
Set this to a number greater than 0 to request paged results
from the LDAP server in accordance with RFC2696. The default
(0) is to not request paged results.
This is useful for LDAP servers that contain a lot of entries
(e.g. more than 500) and limit the number of entries that are
returned with one request. For OpenLDAP servers you may need to
set sizelimit size.prtotal=unlimited for allowing more entries
to be returned over multiple pages.
nss_initgroups_ignoreusers user1,user2,...
This option prevents group membership lookups through LDAP for
the specified users. This can be useful in case of unavailabil‐
ity of the LDAP server. This option may be specified multiple
times.
Alternatively, the value ALLLOCAL may be used. With that value
nslcd builds a full list of non-LDAP users on startup.
nss_min_uid UID
This option ensures that LDAP users with a numeric user id lower
than the specified value are ignored. Also requests for users
with a lower user id are ignored.
validnames REGEX
This option can be used to specify how user and group names are
verified within the system. This pattern is used to check all
user and group names that are requested and returned from LDAP.
The regular expression should be specified as a POSIX extended
regular expression. The expression itself needs to be separated
by slash (/) characters and the 'i' flag may be appended at the
end to indicate that the match should be case-insensetive. The
default value is /^[a-z0-9._@$][a-z0-9._@$
\\~-]*[a-z0-9._@$~-]$/i
ignorecase yes|no
This specifies whether or not to perform searches for group,
netgroup, passwd, protocols, rpc, services and shadow maps using
case-insensitive matching. Setting this to yes could open up
the system to authorisation vulnerabilities and introduce nscd
cache poisoning vulnerabilities which allow denial of service.
The default is to perform case-sensitve filtering of LDAP search
results for the above maps.
pam_authz_search FILTER
This option allows flexible fine tuning of the authorisation
check that should be performed. The search filter specified is
executed and if any entries match, access is granted, otherwise
access is denied.
The search filter can contain the following variable references:
$username, $service, $ruser, $rhost, $tty, $hostname, $fqdn,
$dn, and $uid. These references are substituted in the search
filter using the same syntax as described in the section on
attribute mapping expressions below.
For example, to check that the user has a proper authorizedSer‐
vice value if the attribute is present (this almost emulates the
pam_check_service_attr option in PADL's pam_ldap):
(&(objectClass=posixAccount)(uid=$username)(|(authorizedService=$service)(!(authorizedService=*))))
The pam_check_host_attr option can be emulated with:
(&(objectClass=posixAccount)(uid=$username)(|(host=$hostname)(host=$fqdn)(host=\\*)))
This option may be specified multiple times and all specified
searches should at least return one entry for access to be
granted.
pam_password_prohibit_message "MESSAGE"
If this option is set password modification using pam_ldap will
be denied and the specified message will be presented to the
user instead. The message can be used to direct the user to an
alternative means of changing their password.
SUPPORTED MAPS
The following maps are supported. They are referenced as MAP in the
options above.
alias[es]
Mail aliases. Note that most mail servers do not use the NSS
interface for requesting mail aliases and parse /etc/aliases on
their own.
ether[s]
Ethernet numbers (mac addresses).
group Posix groups.
host[s]
Host names.
netgroup
Host and user groups used for access control.
network[s]
Network numbers.
passwd Posix users.
protocol[s]
Protocol definitions (like in /etc/protocols).
rpc Remote procedure call names and numbers.
service[s]
Network service names and numbers.
shadow Shadow user password information.
ATTRIBUTE MAPPING EXPRESSIONS
For some attributes a mapping expression may be used to construct the
resulting value. This is currently only possible for attributes that
do not need to be used in search filters. The expressions are a subset
of the double quoted string expressions in the Bourne (POSIX) shell.
Instead of variable substitution, attribute lookups are done on the
current entry and the attribute value is substituted. The following
expressions are supported:
${attr} (or $attr for short)
will substitute the value of the attribute
${attr:-word}
(use default) will substitbute the value of the attribute or, if
the attribute is not set or empty substitute the word
${attr:+word}
(use alternative) will substitbute word if attribute is set,
otherwise substitute the empty string
Quote ("), dollar ($) or backslash (\) characters should be escaped
with a backslash (\).
The nslcd daemon checks the expressions to figure out which attributes
to fetch from LDAP. Some examples to demonstrate how these expressions
may be used in attribute mapping:
"${shadowFlag:-0}"
use the shadowFlag attribute, using the value 0 as default
"${homeDirectory:-/home/$uid}"
use the uid attribute to build a homeDirectory value if that
attribute is missing
"${isDisabled:+100}"
if the isDisabled attribute is set, return 100, otherwise leave
value empty
FILES
/etc/nslcd.conf
the main configuration file
/etc/nsswitch.conf
Name Service Switch configuration file
SEE ALSOnslcd(8), nsswitch.conf(5)AUTHOR
This manual was written by Arthur de Jong <arthur@arthurdejong.org> and
is based on the nss_ldap(5) manual developed by PADL Software Pty Ltd.
Version 0.8.14 Mar 2014 nslcd.conf(5)
