Old:Samba e OpenLDAP: creare un controller di dominio con Ubuntu Server Autenticazione LDAP

Installazione e Configurazione dell'autenticazione LDAP

Per prima cosa installeremo il pacchetto libnss-ldap, con il classico comando:

# apt-get install libnss-ldap libpam-ldap

Rispondere alle domande di autoconfigurazione:

* Server LDAP: 192.168.2.1
* Distinguished name (DN): dc=dominio,dc=local
* LDAP version: 3
* Make local root Database admin: sí 
* Si richiede utente per database LDAP: no
* LDAP account for root cn=admin,dc=dominio,dc=local 
* LDAP root password: secret
* Local crypt to use when changing passwords: exop

Se sbagliate a configurare rilanciate la schermata con:

# dpkg-reconfigure ldap-auth-config

Assicuratevi che il file ldap.secret, dal quale traspare la password in chiaro, sia leggibile e scrivibile solo da root. Non impostatela criptata perchè altrimenti non vi autentica. Vi assicuro che se vi accertate dei permessi la password non trasparirà fuori.

Assicuratevi che il l'uri sia settato correttamente in /etc/default/slapd alla voce SLAPD_SERVICES = ldap://192.168.2.1:389, mentre se usate un TLS deve essere settato ldaps://192.168.2.1:636. Ricordatevi di cancellare ldaps:// se usate ldap:// e viceversa.

Editate il file ldap.conf (le prime tre voci dovrebbero essere già editate correttamente mentre le altre voci devono essere decommentate ed editate:

# Your LDAP server. Must be resolvable without using LDAP.
# Multiple hosts may be specified, each separated by a 
# space. How long nss_ldap takes to failover depends on
# whether your LDAP client library supports configurable
# network or connect timeouts (see bind_timelimit).
host 192.168.2.1

# The distinguished name of the search base.
base dc=dominio,dc=local

# Another way to specify your LDAP server is to provide an
uri ldap://192.168.2.1:389
# Unix Domain Sockets to connect to a local LDAP Server.
#uri ldap://127.0.0.1/
#uri ldaps://127.0.0.1/   
#uri ldapi://%2fvar%2frun%2fldapi_sock/
# Note: %2f encodes the '/' used as directory separator

# The LDAP version to use (defaults to 3
# if supported by client library)
ldap_version 3

# The distinguished name to bind to the server with.
# Optional: default is to bind anonymously.
binddn cn=admin,dc=dominio,dc=local

# The credentials to bind with. 
# Optional: default is no credential.
bindpw secret

# The distinguished name to bind to the server with
# if the effective user ID is root. Password is
# stored in /etc/ldap.secret (mode 600)
#rootbinddn cn=admin,dc=dominio,dc=local
# The port.
# Optional: default is 389.
#port 389
#port 636
# The search scope.
scope sub
#scope one
#scope base

# Search timelimit
timelimit 50

# Bind/connect timelimit
bind_timelimit 50

# Reconnect policy: hard (default) will retry connecting to
# the software with exponential backoff, soft will fail
# immediately.
bind_policy soft

# Idle timelimit; client will close connections
# (nss_ldap only) if the server has not been contacted
# for the number of seconds specified below.
#idle_timelimit 3600

# Filter to AND with uid=%s
#pam_filter objectclass=account

# The user ID attribute (defaults to uid)
pam_login_attribute uid

# Search the root DSE for the password policy (works
# with Netscape Directory Server)
#pam_lookup_policy yes

# Check the 'host' attribute for access control
# Default is no; if set to yes, and user has no
# value for the host attribute, and pam_ldap is
# configured for account management (authorization)
# then the user will not be allowed to login.
#pam_check_host_attr yes

# Check the 'authorizedService' attribute for access
# control
# Default is no; if set to yes, and the user has no
# value for the authorizedService attribute, and
# pam_ldap is configured for account management
# (authorization) then the user will not be allowed
# to login.
#pam_check_service_attr yes

# Group to enforce membership of
#pam_groupdn cn=PAM,ou=Groups,dc=padl,dc=com

# Group member attribute
pam_member_attribute memberUid

# Specify a minium or maximum UID number allowed
#pam_min_uid 0
#pam_max_uid 0

# Template login attribute, default template user
# (can be overriden by value of former attribute
# in user's entry)
#pam_login_attribute userPrincipalName
#pam_template_login_attribute uid
#pam_template_login nobody

# HEADS UP: the pam_crypt, pam_nds_passwd,
# and pam_ad_passwd options are no
# longer supported.
#
# Do not hash the password at all; presume
# the directory server will do it, if
# necessary. This is the default.
#pam_password md5

# Hash password locally; required for University of
# Michigan LDAP server, and works with Netscape
# Directory Server if you're using the UNIX-Crypt
# hash mechanism and not using the NT Synchronization
# service. 
#pam_password crypt

# Remove old password first, then update in
# cleartext. Necessary for use with Novell
# Directory Services (NDS)
#pam_password clear_remove_old
#pam_password nds

# RACF is an alias for the above. For use with
# IBM RACF
#pam_password racf

# Update Active Directory password, by
# creating Unicode password and updating
# unicodePwd attribute.
#pam_password ad

# Use the OpenLDAP password change
# extended operation to update the password.
pam_password exop

# Redirect users to a URL or somesuch on password
# changes.
#pam_password_prohibit_message Please visit http://internal to change your password.

# RFC2307bis naming contexts
# Syntax:
# nss_base_XXX		base?scope?filter
# where scope is {base,one,sub}
# and filter is a filter to be &'d with the
# default filter.
# You can omit the suffix eg:
# nss_base_passwd	ou=People,
# to append the default base DN but this
# may incur a small performance impact.
nss_base_passwd dc=dominio,dc=local?sub
nss_base_shadow dc=dominio,dc=local?sub
nss_base_group ou=groups,dc=dominio,dc=local?one
#nss_base_hosts		ou=Hosts,dc=padl,dc=com?one
#nss_base_services	ou=Services,dc=padl,dc=com?one
#nss_base_networks	ou=Networks,dc=padl,dc=com?one
#nss_base_protocols	ou=Protocols,dc=padl,dc=com?one
#nss_base_rpc		ou=Rpc,dc=padl,dc=com?one
#nss_base_ethers	ou=Ethers,dc=padl,dc=com?one
#nss_base_netmasks	ou=Networks,dc=padl,dc=com?ne
#nss_base_bootparams	ou=Ethers,dc=padl,dc=com?one
#nss_base_aliases	ou=Aliases,dc=padl,dc=com?one
#nss_base_netgroup	ou=Netgroup,dc=padl,dc=com?one

# attribute/objectclass mapping
# Syntax:
#nss_map_attribute	rfc2307attribute	mapped_attribute
#nss_map_objectclass	rfc2307objectclass	mapped_objectclass

# configure --enable-nds is no longer supported.
# NDS mappings
#nss_map_attribute uniqueMember member

# Services for UNIX 3.5 mappings
#nss_map_objectclass posixAccount User
#nss_map_objectclass shadowAccount User
#nss_map_attribute uid msSFU30Name
#nss_map_attribute uniqueMember msSFU30PosixMember
#nss_map_attribute userPassword msSFU30Password
#nss_map_attribute homeDirectory msSFU30HomeDirectory
#nss_map_attribute homeDirectory msSFUHomeDirectory
#nss_map_objectclass posixGroup Group
#pam_login_attribute msSFU30Name
#pam_filter objectclass=User
#pam_password ad

# configure --enable-mssfu-schema is no longer supported.
# Services for UNIX 2.0 mappings
#nss_map_objectclass posixAccount User
#nss_map_objectclass shadowAccount user
#nss_map_attribute uid msSFUName
#nss_map_attribute uniqueMember posixMember
#nss_map_attribute userPassword msSFUPassword
#nss_map_attribute homeDirectory msSFUHomeDirectory
#nss_map_attribute shadowLastChange pwdLastSet
#nss_map_objectclass posixGroup Group
#nss_map_attribute cn msSFUName
#pam_login_attribute msSFUName
#pam_filter objectclass=User
#pam_password ad

# RFC 2307 (AD) mappings
#nss_map_objectclass posixAccount user
#nss_map_objectclass shadowAccount user
#nss_map_attribute uid sAMAccountName
#nss_map_attribute homeDirectory unixHomeDirectory
#nss_map_attribute shadowLastChange pwdLastSet
#nss_map_objectclass posixGroup group
#nss_map_attribute uniqueMember member
#pam_login_attribute sAMAccountName
#pam_filter objectclass=User
#pam_password ad

# configure --enable-authpassword is no longer supported
# AuthPassword mappings
#nss_map_attribute userPassword authPassword

# AIX SecureWay mappings
#nss_map_objectclass posixAccount aixAccount
#nss_base_passwd ou=aixaccount,?one
#nss_map_attribute uid userName
#nss_map_attribute gidNumber gid
#nss_map_attribute uidNumber uid
#nss_map_attribute userPassword passwordChar
#nss_map_objectclass posixGroup aixAccessGroup
#nss_base_group ou=aixgroup,?one
#nss_map_attribute cn groupName
#nss_map_attribute uniqueMember member
#pam_login_attribute userName
#pam_filter objectclass=aixAccount
#pam_password clear

# Netscape SDK LDAPS
#ssl on

# Netscape SDK SSL options
#sslpath /etc/ssl/certs

# OpenLDAP SSL mechanism
# start_tls mechanism uses the normal LDAP port, LDAPS typically 636
#ssl start_tls
ssl off

# OpenLDAP SSL options
# Require and verify server certificate (yes/no)
# Default is to use libldap's default behavior, which can be configured in
# /etc/openldap/ldap.conf using the TLS_REQCERT setting.  The default for
# OpenLDAP 2.0 and earlier is "no", for 2.1 and later is "yes".
#tls_checkpeer yes

# CA certificates for server certificate verification
# At least one of these are required if tls_checkpeer is "yes"
#tls_cacertfile /etc/ssl/ca.cert
#tls_cacertdir /etc/ssl/certs

# Seed the PRNG if /dev/urandom is not provided
#tls_randfile /var/run/egd-pool

# SSL cipher suite
# See man ciphers for syntax
#tls_ciphers TLSv1

# Client certificate and key
# Use these, if your server requires client authentication.
#tls_cert
#tls_key

# Disable SASL security layers. This is needed for AD.
#sasl_secprops maxssf=0

# Override the default Kerberos ticket cache location.
#krb5_ccname FILE:/etc/.ldapcache

# SASL mechanism for PAM authentication - use is experimental
# at present and does not support password policy control
#pam_sasl_mech DIGEST-MD5
nss_initgroups_ignoreusers avahi,avahi-autoipd,backup,bin,couchdb,daemon,games,gdm,gnats,hplip,irc,kernoops,libuuid,list,lp,mail,man,messagebus,news,proxy,pulse,root,rtkit,saned,speech-dispatcher,sync,sys,syslog,usbmux,uucp,www-data

Lanciate i seguenti comandi di autoconfigurazione:

# pam-auth-update (Dal menù pam-auth-update, scegliere LDAP e unix, inoltre qualsiasi altro metodo di
  autenticazione necessario.)

# auth-client-config -t nss -p lac_ldap (configura nsswitch.conf all'uso di ldap)

     * -t: modifica solamente /etc/nsswitch.conf.
     
     * -p: nome del profilo da abilitare, disabilitare, ecc...

     * lac_ldap: il profilo auth-client-config parte del pacchetto ldap-auth-config.

Verificare il contenuto di /etc/nsswitch.conf e controllare le seguenti voci se corrispondono:

passwd: files ldap
group: files ldap
shadow: files ldap

hosts:          files dns wins
networks:       files dns

protocols:     db files
services:      db files
ethers:        db files
rpc:           db files

netgroup: nis

A causa di un bug documentato (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=375077) e a cui il team di sviluppo di Debian ha fornito una soluzione parziale (è stato eliminato il problema, ma non i messaggi d'errore generati al boot) è possibile che al reboot compaiano messaggi di errore simili ai seguenti:

...
udevd[1350]: nss_ldap: could not connect to any LDAP server as cn=admin,dc=home,dc=tld - Can't contact LDAP server
udevd[1350]: nss_ldap: failed to bind to LDAP server ldap://127.0.0.1: Can't contact LDAP server
udevd[1350]: nss_ldap: could not search LDAP server - Server is unavailable
udevd[1350]: lookup_user: error resolving user 'tss': Illegal seek 
...

Una possibile via per eludere il problema è quella di aggiungere a mano gli utenti di sistema mancanti:

# addgroup --system tss
# addgroup --system kvm
# addgroup --system rdma
# addgroup --system fuse
# addgroup --system scanner
# addgroup --system nvram
# adduser --system tss