nss-ldapd - NSS library for name lookups using LDAP nss-ldapd is a fork from nss_ldap which was orignally written by Luke Howard of PADL Software Pty Ltd. http://www.padl.com/OSS/nss_ldap.html In 2006 Arthur de Jong of West Consuling forked the library to split it into a thin NSS part and a server part. Most of the code was rewritten. http://ch.tudelft.nl/~arthur/nss-ldapd/ Copyright (C) 1997-2006 Luke Howard Copyright (C) 2006, 2007 West Consulting Copyright (C) 2006, 2007 Arthur de Jong This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA INTRODUCTION ============ This is the nss-ldapd library which is an NSS module to do name lookups to an LDAP directory server. This library was forked from nss_ldap as provided by Luke Howard of PADL Software Pty Ltd. The library is currently work in progress. The library allows distributing account, group, host and other configuration information from a central LDAP server throughout an organisation. Because LDAP is a hierarchical directory service, you can distribute the information in a manner which reflects an organisational structure. This contrasts with the flat, single domain policy of NIS. LDAP has many of the advantages of NIS+ (security and scalability) without the complexity. The system will work alongside your existing NIS, NIS+, DNS and flat file name services. This library consists of a thin NSS part that communicates with a local server that handles the LDAP lookups. This simplifies the architecture and fixes some scalability and locking problems with the original design. improvements over nss_ldap -------------------------- The fork from nss_ldap was done to implement some major design changes to fix some structural problems in the library. The biggest of those problems were host name lookups through LDAP (which could cause deadlocks in most cases) and problems during booting (when the LDAP server was not started or not yet reachable). With nss-ldapd a number of refactoring steps were taken to simplify the code and improve maintainability. Legacy code was removed and support for non-Linux operating systems was initially removed to make the code more readable. Portability will be re-added once the architecture stabilises. The most practical improvements of nss-ldapd over nss_ldap are: * the LDAP library is not loaded for every process doing LDAP lookups * the number of connections to the LDAP server is limited, because not every process will open it's own connection (this problem is also mitigated by using nscd) * hostname lookups should now be deadlock-free because the LDAP server name lookup no longer uses the ldap method * the setup is easier to debug because loggin on the server component can be enabled without affecting "normal" processes This package runs a local daemon that will be enabled during the boot process. This daemon will handle connections to the LDAP server and accept NSS requests from a named socket (/var/run/nslcd/socket). The thin NSS library will proxy requests to the daemon. Note that the package currently cannot be used on the same system alongside nss_ldap. supported C libraries --------------------- This library currently only supports the GNU C Library. Support for other C libraries has been removed in a refactoring step. Compatibility code and support for other C libraries will be added in due time. supported name databases ------------------------ Currently the following name databases are supported: aliases, ethers, group, hosts, netgroup, networks, passwd, protocols, rpc, services and shadow Note that for when using IPv6 hosts entries, the addresses in the LDAP directory must be in their preferred form. The same is true for mac addresses for the ethers database. Otherwise the address->entry lookups will not work. For more details see http://ldap.akbkhome.com/index.php/attribute/ipHostNumber.html and http://ldap.akbkhome.com/index.php/attribute/macAddress.html automounter map lookups (which are also defined in /etc/nsswitch.conf) are not supported because the NSS interface is not used for these. The common autofs implementation currently uses it's own method for getting the maps from LDAP. The publickey, bootparams and netmasks are currently also unsupported. Some investigation should be done if these are needed for anything, which interfaces should be exported and how the LDAP schema part should look like. supported LDAP libraries ------------------------ The current version of nss-ldapd has been developed with OpenLDAP 2.1.30 but adding support for other LDAP libraries with similar interfaces should not be too hard. The server part of the code is however still being refactored and cleaned up and the LDAP part is still subject to change and simplification. unsupported features -------------------- Since nss-ldapd was forked from nss_ldap most of the features that came with nss_ldap are available. However, not all features have extensively tested yet and may cause problems. - attribute mapping should work but did not receive adequate testing (but the configuration syntax has changed) - attribute value default and overrides are not supported and may be removed in a coming release (but may reappear some day if requested) - the manual page for nss-ldap.conf is horribly outdated and includes incorrect information - paged results support is untested - SSL/TLS support is untested but will be tested when the core code stabilizes - the configuration file formats will change In general, development is ongoing and a lot has to be cleaned up. The focus is to have the functionality that is present be well tested and supported. INSTALLATION ============ The nss-ldapd library uses autoconf and automake for building. Installing nss-ldapd should be as simple as: % ./configure % make % make install That said, it is a good idea to go first through the options of configure by running: % ./configure --help The last step (make install) should install the libnss_ldap.so.* file and the daemon (nslcd). The boot process needs to be manually modified to start the daemon at the right time. CONFIGURATION ============= After installation the name service switch configuration file (/etc/nsswitch.conf) needs to be modified to do name lookups using the new module. Also, the nss-ldapd configuration file (specified at configure time) needs to be modified to contain to the correct LDAP configuration. Editing nsswitch.conf consist mostly of adding ldap in the list of lookup methods in the right place. See the nsswitch.conf(5) manual page for details on the format. As an example the file could look a little like this: # the following contain normal unix user and group information passwd: files ldap group: files ldap shadow: files ldap # hostname lookups through ldap before dns should work now hosts: files ldap dns networks: files ldap # normal flat-file definitions protocols: files ldap services: files ldap ethers: files ldap rpc: files ldap netgroup: ldap # whether alias lookups really use NSS depends on the mail server aliases: files ldap Furthermore a LDAP configuration file (by default /etc/nss-ldapd.conf) needs to be made. The location of this file can be specified with configure. See the shipped manual page for details on the format and options. It should at least contain something like: # the location of LDAP server uri ldap://localhost/ # search base for all queries. base dc=example,dc=net # LDAP protocol version ldap_version 3 LDAP SCHEMA =========== nss-ldapd supports a wide range of possible LDAP schema configurations. Furthermore it can be customized heavily. The LDAP schema used is described in RFC 2307. Groups with distinguished name members (instead of login names) (RFC 2307bis) is also supported. A posixGroup can thus have the both memberUid and uniqueMember attributes. default attributes ------------------ This paragraph describes the mapping between the NSS lookups and the LDAP database. The mapping may be modified by changeging the nss-ldapd.conf configuration file. See the nss-ldapd.conf(5) manual page for details. aliases (objectClass=nisMailAlias) cn - alias name rfc822MailMember - members ethers (objectClass=ieee802Device) cn - host name macAddress - ethernet address group (objectClass=posixGroup) cn - group name userPassword - should be readable by rootbinddn only memberUid - members uniqueMember - members gidNumber - gid hosts (objectClass=ipHost) cn - host name (and aliases) ipHostNumber - addresses netgroup (objectClass=nisNetgroup) cn - netgroup name nisNetgroupTriple - triplets describing netgroup entries memberNisNetgroup - reference to other netgroup networks (objectClass=ipNetwork) cn - network name ipNetworkNumber - network address ipNetmaskNumber - network netmask passwd (objectClass=posixAccount) uid - account name userPassword - should be readable by rootbinddn only uidNumber - uid gidNumber - gid cn - gecos homeDirectory - home directory loginShell - shell gecos - gecos protocols (objectClass=ipProtocol) cn - protocol name ipProtocolNumber - protocol number rpc (oncRpc) cn - rpc name oncRpcNumber - rpc number services (objectClass=ipService) cn - service name ipServicePort - service port ipServiceProtocol - service protocol shadow (objectClass=shadowAccount) uid - use name userPassword - should be readable by rootbinddn only shadowLastChange - last change of password shadowMax - days before password may be changed shadowMin - days after which password must be changed shadowWarning - expiry warning shadowInactive - account is disabled if no passwd is changed shadowExpire - account expiration shadowFlag - reserved field using Microsoft Active Directory -------------------------------- When using Microsoft Active Directory server (typically on Microsoft Windows 2000) some changes need to be made to the nss-ldapd.conf configuration file. The default configuration file has some commented out attribute mappings for such a setup. MISC NOTES ========== Most values in the NSS databases are considered case-sensitive (e.g. the user "Foo" is a different user from "foo"). Values in an LDAP database are however case-insensitive. This may cause problems in some corner cases, especially when nscd is used for caching. For example when doing a lookup for the user "Foo" the user "foo" will be returned if it exists in the database.