NAME¶
nslcd.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 historically
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.
- log SCHEME [LEVEL]
- This option controls the way logging is done. The SCHEME argument
may either be none, syslog or an absolute file name. The LEVEL
argument is optional and specifies the log level. The log level may be one
of: crit, error, warning, notice, info or debug. The default log level is
info. All messages with the specified loglevel or higher are logged. This
option can be supplied multiple times. If this option is omitted syslog
info is assumed.
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 anonymously.
- 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 applicable 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
authentication.
- 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 canonicalised. 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 specified 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|children
- Specifies the search scope (subtree, onelevel, base or children). The
default scope is subtree; base scope is almost never useful for name
service lookups; children scope is not supported on all servers.
- 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: userPassword, gidNumber, gecos, homeDirectory and
loginShell. For shadow entries the following attributes may be mapped with
an expression: userPassword, shadowLastChange, shadowMin, shadowMax,
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.
objectSid:S-1-5-21-3623811015-3361044348-30300820).
By default all userPassword attributes are mapped to the unmatchable
password ("*") to avoid accidentally leaking password
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 simpler 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 certificate. 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 authentication.
- 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 implementation'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 unavailability 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.
- nss_nested_groups yes|no
- If this option is set, the member attribute of a group may point to
another group. Members of nested groups are also returned in the higher
level group and parent groups are returned when finding groups for a
specific user. The default is not to perform extra searches for nested
groups.
- 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 $uid. These
references are substituted in the search filter using the same syntax as
described in the section on attribute mapping expressions below.
For example, to check that the user has a proper authorizedService value if
the attribute is present (this almost emulates the
pam_check_service_attr option in PADL's pam_ldap):
(&(objectClass=posixAccount)(uid=$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.
- reconnect_invalidate DB,DB,...
- If this option is set, on start-up and whenever a connection to the LDAP
server is re-established after an error the specified caches are flushed.
If DB is one of the nsswitch maps, nscd is contacted to flush
its cache for the specified database. If DB is nfsidmap,
nfsidmap is contacted to clear its cache.
Using this option ensures that external caches are cleared of information
(typically the absence of users) while the LDAP server was
unavailable.
- cache CACHE TIME [TIME]
- Configure the time entries are kept in the specified internal cache.
The first TIME value specifies the time to keep found entries in the
cache. The second TIME value specifies to the time to remember that
a particular entry was not found. If the second parameter is absent, it is
assumed to be the same as the first.
Time values are specified as a number followed by an s for seconds, m for
minutes, h for hours or d for days. Use 0 or off to disable the cache.
Currently, only the dn2uid cache is supported that is used to remember DN to
username lookups that are used when the member attribute is used. The
default time value for this cache is 15m.
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
- ${attr#word}
- remove the shortest possible match of word from the left of the attribute
value
- ${attr##word}
- remove the longest possible match of word from the left of the attribute
value ( pynslcd only)
- ${attr%word}
- remove the shortest possible match of word from the right of the attribute
value ( pynslcd only)
- ${attr%%word}
- remove the longest possible match of word from the right of the attribute
value ( pynslcd only)
Only the # matching expression is supported in
nslcd and only with the ?
wildcard symbol. The
pynslcd implementation supports full matching.
Quote ("), dollar ($) and backslash (\) characters should be escaped with a
backslash (\).
The expressions are checked 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
- "${userPassword#{crypt\}}"
- strip the {crypt} prefix from the userPassword attribute, returning the
raw hash value
FILES¶
- /etc/nslcd.conf
- the main configuration file
- /etc/nsswitch.conf
- Name Service Switch configuration file
SEE ALSO¶
nslcd(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.