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Difference between revisions of "NSS LDAP"

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(LDAP Server Software: Added configuration notes. Incomplete.)
(Configuration Notes: Section complete.)
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**ldapadd the nssindexes.ldif file to add all the other indexes that we want.
 
**ldapadd the nssindexes.ldif file to add all the other indexes that we want.
 
**Indexes shouldn't need to be regenerated since there shouldn't be any data in the directory yet.
 
**Indexes shouldn't need to be regenerated since there shouldn't be any data in the directory yet.
*Adjust the default cache values.  Select the LDAP instance, then go to Server Configuration -> TO BE COMPLETED.
+
*Adjust the default cache values.  Select the LDAP instance, then go to Server Configuration.
 +
**On the LDAP subtab, set the Size Limit and Lookthrough Limit to Unlimited.  The default 3600 second Time Limit and Unlimited Idle Timeout should be fine.
 +
**On the Performance subtab, change the following values:
 +
***Database Cache (Global): 256 MB
 +
***Initialization Cache (Global): 512 MB
 +
***Cache Size Limits: dc=csl,dc=tjhsst,dc=edu: 64 MB
 +
**On the Plugins subtab, select the "referential integrity postoperation" plugin.  Set the Argument 1 to "2".  This should make mass modifications and deletions faster[http://blogs.sun.com/DirectoryManager/entry/little_known_performance_enhancements_3].  This plugin is enabled by Identity Synchronization, so at the time you change the setting, the plugin may still be disabled.
  
 
==Sun Java System Identity Synchronization for Windows==
 
==Sun Java System Identity Synchronization for Windows==

Revision as of 11:59, 12 August 2008

LDAP is used to store NSS (Name Service Switch) information for the UNIX passwd and group databases. All information about network users, such as UNIX uid/gid, home directory, shell, and other group membership is handled through NSS.

History

Previously, the CSL used NIS to store network user information. However, when the decision was made to integrate CSL accounts and authentication with Windows Active Directory (previously all CSL accounts were managed separately and required an application form to receive), LDAP was chosen to replace NIS as the backend for the NSS database.

Integrated authentication using LDAP and Kerberos was initially deployed in lab 231 during the spring of 2006. Sun Directory Server 5.2 was used at the time, replicated from sol across what are now known as chuku and ekhi. During the summer following, LDAP was moved into a VMWare virtual machine known as daystar in order to run LDAP on a faster system. However, for reasons not completely understood, the VM subsequently developed problems during the fall of 2006 and resulted in NSS becoming painfully slow on both rockhopper (at that time used for all of lab 231 and 16 LTSP nodes in the CSL) and the rest of the CSL workstations. In order to remedy the situation, /etc/passwd was rapidly deployed as a flatfile across all affected systems. Hesiod was subsequently set up as the NSS database for the remainder of the school year and the beginning of the next.

During the winter of 2007-08, NSS was switched back to LDAP following various discussions. (Need more information.) LDAP was configured on chuku and mihr, running Sun Directory Server 6.

Current

NSS LDAP is currently used by nearly all *NIX systems managed by the CSL. It is running in LDOMs ldap1 and ldap2.

Configuring LDAP on clients

Linux

  • libnss-ldap (or similar) needs to be installed.
  • Edit /etc/libnss-ldap.conf:
    • Setup LDAP servers 198.38.16.59:388, 198.38.16.12:388, and 198.38.16.13:388.
    • Use search base: dc=csl,dc=tjhsst,dc=edu.
    • Set bind_timelimit to 2
    • Set bind_policy to soft
    • Set nss_base_passwd to ou=people,
    • Set nss_base_group to ou=group,
  • Edit /etc/nsswitch.conf to use "files ldap" for the passwd and group databases. The two lines should look like this:
passwd:     files ldap
group:      files ldap
  • You may need to restart nscd.

Solaris

WARNING: There was at least one point in the history of Sun Directory Server where setting up the LDAP client on the LDAP server was not supported because the client was started before the server was, causing a halt in system boot because of a failure to initialize the client. I'm not sure if this is still the case, but if it is, you will need an init script to disable the client in SMF until the server starts, and then restart the client after the server starts. In the CSL, this is easily done by installing the STJinitd-sunds package.

  • Run the following command:
/usr/sbin/ldapclient manual -a credentialLevel=anonymous \
 -a defaultSearchBase="dc=csl,dc=tjhsst,dc=edu" \
 -a defaultSearchScope=sub \
 -a defaultServerList="198.38.16.12:388 198.38.16.13:388" \
 -a followReferrals="TRUE" \
 -a preferredServerList="198.38.16.59:388" \
 -a serviceSearchDescriptor=passwd:ou=people,dc=csl,dc=tjhsst,dc=edu \
 -a serviceSearchDescriptor=group:ou=group,dc=csl,dc=tjhsst,dc=edu
  • On most CSL systems: You are done.
  • On stock Solaris systems (and possibly some CSL systems):
    • The ldapclient command has installed an nsswitch.conf that assumes you use LDAP for everything. And I mean EVERYTHING. But that's rarely the case anywhere. So cp /etc/nsswitch.dns /etc/nsswitch.conf. Then edit /etc/nsswitch.conf to use "files ldap" for passwd and group. See Linux section above for sample of what this will look like.
    • pkill nscd to restart it (Solaris 10), or restart it some other way.

Admin-only access

Follow the above directions, but wherever you see an ou=people, replace it with an ou=sysadmins. Only sysadmins with LDAP entries in ou=sysadmins will be able to access that system. Note that additional access control can, and is often, managed by using hostname groups (i.e. the LDAP POSIX group named after the hostname of the system). This is currently not done on Solaris systems, but is done on most Linux systems.

LDAP Server Software

Both of the below applications are part of Sun Java System Directory Server Enterprise Edition 6.

NOTE: If the database needs to be rebuilt from scratch and data reloaded from LDIF dumps, you may need to get Identity Synchronization to "prepare" Directory Server as it needs to modify the schema with new object classes and attribute types.

Sun Java System Directory Server

  • Sun's implementation of an LDAP server.
  • Can fully integrate with nsswitch for all NSS databases (currently only using passwd and group).
  • Currently running in one-way replication on ldap1 (master) and ldap2.

Configuration Notes

Any configuration steps listed below that are server-specific must be run on each LDAP instance!

  • Currently ports 388 (non-SSL) and 635 (SSL) are used for NSS LDAP, but that is not a requirement. It is used because NSS LDAP used to coexist with another LDAP instance at the same IP address that used the normal 389/636 ports. While that is no longer the case, the port numbers were kept to reduce impact on already configured client systems.
  • The databases are currently stored using ZFS, located at /store/ds/nss.
  • When installing DSEE, choose "Configure Later". After installation completes, run the following sequence of commands to use the DSCC (not a typo) web management interface:
/opt/SUNWdsee/dscc6/bin/dsccsetup initialize
cacaoadm enable
cacaoadm start
smcwebserver enable
smcwebserver start
  • We use the wildcard SSL certificate from ipsCA rather than a self-signed one for LDAP because we have it and it works. It needs to be imported in PKCS12 format (the password for which cannot be null). As last attempted, this process seems to be a little more involved than it should:
    • Import the certificate
    • Restart the Directory Server instance
    • Now switch to the new certificate
    • Restart again
  • To change the manager password, run ldapmodify with the appropriate arguments against this:
dn: cn=config
changetype: modify
replace: nsslapd-rootpw
nsslapd-rootpw: newpassword
  • To enable starting the server at boot time using SMF, run
/opt/SUNWdsee/ds6/bin/dsadm enable-service -T SMF /path/to/directory

DSCC's LDAP server is located at /var/opt/SUNWdsee/dscc6/dcc/ads, while NSS LDAP is currently located at /store/ds/nss. Also run svccfg -s application/sun/ds setprop start/timeout_seconds=600 in the event that a recovery needs to take a long time, otherwise SMF will kill and restart the LDAP server if a recovery operation takes longer than the default timeout (which means the directory server may not ever automatically restart after a system crash). Finally run svcadm enable on the new SMF entries created for the Directory Servers. sun/ds:default doesn't start anything so you don't need to enable that.

  • Verify that the following 4 acis exist on the root dn entry dc=csl,dc=tjhsst,dc=edu (easily done by reading a backup LDIF dump):
aci: (targetattr="dspswpassword")(version 3.0; acl "No read access to dspswpas
 sword"; deny(read, search, compare) userdn="ldap:///anyone";)
aci: (targetattr="dspswuserlink || dspswloop || dspswvalidate")(version 3.0; a
 cl "deny write access to dspswuserlink, dspswloop, dspswvalidate"; deny(writ
 e) userdn="ldap:///self";)
aci: (targetattr="*")(version 3.0; acl "Full rights for PSW Connector"; allow(
 all) userdn="ldap:///uid=PSWConnector,dc=csl,dc=tjhsst,dc=edu";)
aci: (target="ldap:///dc=csl,dc=tjhsst,dc=edu")(targetattr !="aci")(version 3.
 0;acl "anonymous, no acis"; allow (read, search, compare) userdn = "ldap:///
 anyone";)
  • In order for NSS LDAP to fully work for Solaris clients, we need to set up VLV indexes (nowadays sometimes referred to as "browsing indexes". This must be done on EACH replica server, not just the master(s). Without these indexes, while the system will probably work fine, you won't be able to "dump" the NSS databases using getent passwd or getent group.
    • From the DSCC web interface, select the LDAP instance, then go to Entry Management -> Access Control
    • Edit the "VLV Request Control" entry to apply to ldap:///anyone instead of ldap:///all (anyone means anonymous access while all means any bound user)
    • On the command line, ldapadd the vlvindexes.ldif file (currently located in the ds folder on the Sun admin volume)
    • Stop the directory instance
    • Generate the VLV indexes: dsadm reindex -l -b -t csl.tjhsst.edu.getpwent -t csl.tjhsst.edu.getgrent /store/ds/nss csl
  • We also want to supplement the default attribute indexes. After logging into the DSCC, go to Directory Servers -> Suffixes -> [choose the suffix] -> Indexes.
    • For "uid", enable Presence and Substring (Equality should already be enabled).
    • ldapadd the nssindexes.ldif file to add all the other indexes that we want.
    • Indexes shouldn't need to be regenerated since there shouldn't be any data in the directory yet.
  • Adjust the default cache values. Select the LDAP instance, then go to Server Configuration.
    • On the LDAP subtab, set the Size Limit and Lookthrough Limit to Unlimited. The default 3600 second Time Limit and Unlimited Idle Timeout should be fine.
    • On the Performance subtab, change the following values:
      • Database Cache (Global): 256 MB
      • Initialization Cache (Global): 512 MB
      • Cache Size Limits: dc=csl,dc=tjhsst,dc=edu: 64 MB
    • On the Plugins subtab, select the "referential integrity postoperation" plugin. Set the Argument 1 to "2". This should make mass modifications and deletions faster[1]. This plugin is enabled by Identity Synchronization, so at the time you change the setting, the plugin may still be disabled.

Sun Java System Identity Synchronization for Windows

  • Connects and synchronizes users from Active Directory to Sun LDAP server and maps specified attributes (currently only one-way from AD to Sun).
  • User creation, attribute modification, and account lockout is synchronized. User deletions are not enabled since we want to preserve users' NSS entries for all time.
  • Note that this software is pretty old and sometimes gets finicky, needing a reinstall or other strange fixes. When running the installer, use the GUI installer and not the text-mode as there are some things that aren't fully implemented in the text-mode installer that will later cause many headaches.

Attribute Mappings

Description Active Directory Sun LDAP
Username samAccountName uid
Password (hashed) unicodepwd userpassword
First name givenname givenname
Surname sn sn
Full Name cn cn
Display Name displayName displayName
Description (grad year for current students) description description

Directory Structure

  • Everything below is relative to a root dn of dc=csl,dc=tjhsst,dc=edu.
  • The subtree ou=Services and entry uid=PSWConnector are used by Identity Synchronization. Please do not touch those entries.
  • Groups are referenced by cn (i.e. cn=allaccess,ou=group,dc=csl,dc=tjhsst,dc=edu). Users are referenced by uid (i.e. uid=wyang,ou=2008,ou=students,ou=people,dc=csl,dc=tjhsst,dc=edu).

ou=group

This subtree contains POSIX groups. Currently we have 3 major classes of groups:

  • Primary: Each LDAP user's default group is one of these. There are a few subclasses:
    • Students/graduation year: The name of each group is TJ and then a two digit year, except in the case of 2000, which has name TJ2K. The gidnumber is the four digit graduation year.
    • "Adult" users: Staff members are assigned to group "faculty" with gidnumber 1984. Separating parents/external users into a separate group would be advisable, but they presently share the "faculty" group.
    • "users": This is presently used for all LDAP user entries in the ou=sysadmins subtree (see below).
  • Host/VM access control: Each of these groups (gid starting at 1000) has the hostname of the system that it is designed to control access for. The group has a list of users that should be granted login access to that system; however, some of the systems listed may not necessarily have group control implemented, rendering the LDAP group's membership moot. The group is not used to grant root access on a system; that is controlled independent of LDAP at this time. The members of the "allaccess" group (gid 1337) are grant login access on all systems that have the LDAP group access control scheme configured.
  • System/service groups: These are primarily used by the Solaris systems, but can also be used by others. It is sometimes easier to ensure that any particular group used by a system service will have the same ID across multiple systems by adding it to LDAP, hence the existence of this class of groups. These have gids starting at 5000.

There are some miscellaneous groups scattered in there. For instance, "commons_mm" (gid 8000) is the primary group for all music card users.

ou=people

This is the subtree used for the NSS passwd database on all general use systems. It is itself made up of several more sub-ous. The major ones are listed below. Others may be created as needed (for example, the josti2008 ou contains temporary users that were created for a JOSTI 2008 interactive user experience in one particular presentation; although the users are still in LDAP, they cannot login because their Kerberos credentials are expired).

ou=legacy

Most NIS users were loaded into this ou so legacy accounts could still have their uids looked up, and previous admins that retained their Kerberos accounts can still log in. Some NIS users were not imported because their username already existed in one of the other ous.

ou=parents

Parents that have login access for website editing or for whatever other purpose go here. Some parents may actually be in ou=legacy if they were created during the NIS era.

ou=special

This contains things that don't belong in any other category. Some system service users go here (see "System/service groups" in the ou=group section above for why we do this). Music card users also go here, although they could also have their own ou since there seem to be enough of them nowadays.

  • IMPORTANT: Most users that are added here should also be added to the ou=special in ou=sysadmins (see below).

ou=staff

Well yes...faculty and staff have their own ou. Naturally.

ou=students

No student users go directly in here; they go into another subou under this ou by graduation year first. At time of writing, ous exist for 2006 through 2050 (most of these latter ones are empty).

ou=sysadmins

This contains...well...sysadmins. The distinction from ou=people is primarily for access control on non-general-use servers.

ou=special

This is basically a copy of ou=special from above. The difference is that non-general-use servers are configured to see this ou=special, while general-use systems see the one in ou=people. For example, it is important to have the music card users here and above since music card users are logged in to on a general use system, but the NFS server, which is non-general use, also needs to be able to look up the username and uid.

Administration/Management

Scripts

Currently there are a few bash scripts to help with administration. They are currently located on the Sun administrative volume in the "ds" directory.

update_nssldap.sh

This is the big one. While Identity Synchronization will create the new LDAP entries when new AD user objects are created, it doesn't know how to fill in all the POSIX values, such as uid and home directory. So we have a script that can fill them in. This script iterates on all accounts that do not have the posixAccount objectClass set yet.

This script must be run by someone with AFS admin. It must be run on a system that has the AFS client and tools installed as it handles the AFS side of user-creation as well. It currently must also be run on a system with both the Sun LDAP tools in /usr/bin and the OpenLDAP tools in /usr/local/bin. Perhaps someone should try and rewrite the script to only need one set of tools. Currently it is recommended to run this script on arcturus. The NSS LDAP Manager password will also be needed to gain admin-level access to LDAP. (Again, maybe someone wants to implement GSSAPI or other binding mechanism that allows users to be admins without knowing the Manager password.)

Should the active NSS LDAP database become lost or corrupted and no backups workable, requiring a rebuild from scratch, historical NSS data will be lost. However, the update_nssldap.sh script knows how to retrieve user information from AFS using pts, so users and home directories will not be duplicated if they already exist in AFS. This feature depends on usernames being unique for all time, which they should be by now.

Home directories are created from a skeleton found at /afs/csl.tjhsst.edu/service/skel. Adjust the afs_server and afs_vicep variables to control what server and partition new homedir volumes are created on. Some other variables may also be of interest, such as quota and host.

If the directory structure of AFS or LDAP ever changes for either students or staff, this script will need to be reviewed and updated, otherwise things will fail and/or get created in the wrong places!

backup.sh

The name says it all. The database is dumped out in a dumps subdirectory. Each backup operation creates 2 LDIFs, one for the data and another for ACIs. Files are created with the format hostname.dumpYYYYMMDDHHmmss, with an ending of acis.ldif or .ldif, depending on the contents.

This script may be run from any Solaris system that has the Sun LDAP client tools in /usr/bin. Again, Manager access will be needed. Dumps will be sent to the dumps directory in whatever your current working directory is; traditionally dumps have been kept in ds/dumps on the Sun admin volume.

If the LDAP server changes, this script will need to be updated.

group_manage.sh

This script makes it easy to add users to groups. It can be cumbersome to use for a lot of users, so you might find it easier to read the code and generate your own LDIF to import to the LDAP server if handling many users. It does NOT create or delete groups, nor does it remove users from groups. To perform those operations, the script will need to be written to do more, or you will need to use one of the two below methods.

This script may be run from any Solaris system that has the Sun LDAP client tools in /usr/bin. Again, Manager access will be needed. See update_nssldap.sh section for comment on using GSSAPI or other binding for other users to make changes to LDAP. If that's implemented, group administration should be delegatable so, for instance, shodan's administrator can add users to the shodan group without being able to add users to the fiordland group.

If the LDAP server or directory structure changes, this script will need to be updated.

Web interface

Access to the web interface is on the primary LDAP server only at this time. The Directory Service Control Center (DSCC) is accessed through the Sun Java Web Console, available at https://ldap1.sun.tjhsst.edu:6789/. This address is NOT open to the world; you will need to be on the TJ network to access it. To login to Web Console, use the root account and password. Once logged into the Web Console, you will need to launch the DSCC app. Login as "admin" with the DSCC admin password. DSCC makes it easy to manage multiple Sun Directory Server instances on any number of servers.

Details of how to use the console aren't provided here, but here is a short list of things you can do:

  • Manage replication
  • Restart LDAP servers
  • Modify performance parameters (indexing, caches, etc.)
  • Access logs
  • Manage entries (mostly users and groups)

Note that server-specific changes should be made to both servers; i.e. server configuration is not replicated. However, if setting up new LDAP servers, it may be easier to finish setting up one server before setting up its partner as many settings can be copied from an existing LDAP server by DSCC.

If the primary LDAP server (not just the service) is down, the console will also be unavailable as it runs there. There should be a way to replicate DSCC settings as well since it is just dependent on another smaller LDAP instance; however, we do not currently use it as the need doesn't seem to be there. Note that an LDAP server can only be registered in one DSCC at a time.

CLI tools

This just means you can use ldapadd, ldapmodify, ldapdelete, etc. to work on LDAP. Either Sun LDAP client tools or OpenLDAP tools may be used, just be aware that syntaxes may vary for command line options and binary or hashed contents in LDIFs.

dsadm command on the LDAP servers is also used to manage the server instance itself. It is located in /opt/SUNWdsee/ds6/bin, which should already be in the PATH.

Everything that can be done through the web interface should also be doable using CLI tools, albeit not always as easily.

See Also