1. Integration of Ubuntu clients into a UCS domain#
Univention Corporate Server allows the integration of Ubuntu clients. Initially a standard Ubuntu installation needs to be performed. The following section describes the configuration changes, which need to be made to integrate the Ubuntu client into the UCS domain. After successful integration users can authenticate on the Ubuntu clients with their standard UCS domain password and username.
This configuration has been tested with Ubuntu 14.04 LTS, Ubuntu 16.04 LTS as well as Kubuntu 14.04 LTS.
Caution
In case a command fails or does not return the expected output, please make sure that all configuration options and files are entered and have been written as shown in this document. For example, some text editors do not preserve the indentation which is required for some configuration files.
1.2. Configuration of the System Security Services Daemon (SSSD)#
SSSD provides a set of daemons to manage access to remote directories and authentication mechanisms.
# Become root
$ sudo bash
$ . /etc/univention/ucr_primary_directory_node
# Install SSSD based configuration
$ DEBIAN_FRONTEND=noninteractive apt-get -y install sssd libnss-sss libpam-sss libsss-sudo
# Create sssd.conf
$ cat >/etc/sssd/sssd.conf <<__EOF__
[sssd]
config_file_version = 2
reconnection_retries = 3
sbus_timeout = 30
services = nss, pam, sudo
domains = $kerberos_realm
[nss]
reconnection_retries = 3
[pam]
reconnection_retries = 3
[domain/$kerberos_realm]
auth_provider = krb5
krb5_kdcip = ${primary_directory_node_ip}
krb5_realm = ${kerberos_realm}
krb5_server = ${ldap_master}
krb5_kpasswd = ${ldap_master}
id_provider = ldap
ldap_uri = ldap://${ldap_master}:7389
ldap_search_base = ${ldap_base}
ldap_tls_reqcert = never
ldap_tls_cacert = /etc/univention/ssl/ucsCA/CAcert.pem
cache_credentials = true
enumerate = true
ldap_default_bind_dn = cn=$(hostname),cn=computers,${ldap_base}
ldap_default_authtok_type = password
ldap_default_authtok = $(cat /etc/ldap.secret)
__EOF__
$ chmod 600 /etc/sssd/sssd.conf
# Install auth-client-config
$ DEBIAN_FRONTEND=noninteractive apt-get -y install auth-client-config
# Create an auth config profile for sssd
$ cat >/etc/auth-client-config/profile.d/sss <<__EOF__
[sss]
nss_passwd= passwd: compat sss
nss_group= group: compat sss
nss_shadow= shadow: compat
nss_netgroup= netgroup: nis
pam_auth=
auth [success=3 default=ignore] pam_unix.so nullok_secure try_first_pass
auth requisite pam_succeed_if.so uid >= 500 quiet
auth [success=1 default=ignore] pam_sss.so use_first_pass
auth requisite pam_deny.so
auth required pam_permit.so
pam_account=
account required pam_unix.so
account sufficient pam_localuser.so
account sufficient pam_succeed_if.so uid < 500 quiet
account [default=bad success=ok user_unknown=ignore] pam_sss.so
account required pam_permit.so
pam_password=
password requisite pam_pwquality.so retry=3
password sufficient pam_unix.so obscure sha512
password sufficient pam_sss.so use_authtok
password required pam_deny.so
pam_session=
session required pam_mkhomedir.so skel=/etc/skel/ umask=0077
session optional pam_keyinit.so revoke
session required pam_limits.so
session [success=1 default=ignore] pam_sss.so
session required pam_unix.so
__EOF__
$ auth-client-config -a -p sss
# Restart sssd
$ service sssd restart
The commands getent passwd and getent group should now also display all users and groups of the UCS domain.
1.3. Configuring user logins#
The home directory of a user should be created automatically during login:
# Become root
$ sudo bash
$ cat >/usr/share/pam-configs/ucs_mkhomedir <<__EOF__
Name: activate mkhomedir
Default: yes
Priority: 900
Session-Type: Additional
Session:
required pam_mkhomedir.so umask=0022 skel=/etc/skel
__EOF__
$ DEBIAN_FRONTEND=noninteractive pam-auth-update --force
During login users should also be added to some system groups:
# Become root
$ sudo bash
$ echo '*;*;*;Al0000-2400;audio,cdrom,dialout,floppy,plugdev,adm' \
>>/etc/security/group.conf
$ cat >>/usr/share/pam-configs/local_groups <<__EOF__
Name: activate /etc/security/group.conf
Default: yes
Priority: 900
Auth-Type: Primary
Auth:
required pam_group.so use_first_pass
__EOF__
$ DEBIAN_FRONTEND=noninteractive pam-auth-update --force
By default the Ubuntu login manager only displays a list of local users during login. After adding the following lines an arbitrary user name can be used:
# Become root
$ sudo bash
# Add a field for a user name, disable user selection at the login screen
$ mkdir /etc/lightdm/lightdm.conf.d
$ cat >>/etc/lightdm/lightdm.conf.d/99-show-manual-userlogin.conf <<__EOF__
[SeatDefaults]
greeter-show-manual-login=true
greeter-hide-users=true
__EOF__
Kubuntu 14.04 uses AccountService, a D-Bus interface for user
account management, which ignores the
/etc/lightdm.conf file. Since there is no
configuration file for AccountService the login theme needs to be
changed to classic under .
With these settings the login for domain members should be possible after a restart of LightDM or a reboot.
1.4. Kerberos integration#
Every UCS domain provides a Kerberos domain. Since Kerberos relies on DNS, the Ubuntu client should use a UCS Directory Node (Primary Directory Node, Backup Directory Node or Replica Directory Node) as its DNS server. The following steps provide an example configuration for Kerberos:
# Become root
$ sudo bash
$ . /etc/univention/ucr_primary_directory_node
# Install required packages
$ DEBIAN_FRONTEND=noninteractive apt-get install -y heimdal-clients ntpdate
# Default krb5.conf
$ cat >/etc/krb5.conf <<__EOF__
[libdefaults]
default_realm = $kerberos_realm
kdc_timesync = 1
ccache_type = 4
forwardable = true
proxiable = true
default_tkt_enctypes = arcfour-hmac-md5 des-cbc-md5 des3-hmac-sha1 des-cbc-crc des-cbc-md4 des3-cbc-sha1 aes128-cts-hmac-sha1-96 aes256-cts-hmac-sha1-96
permitted_enctypes = des3-hmac-sha1 des-cbc-crc des-cbc-md4 des-cbc-md5 des3-cbc-sha1 arcfour-hmac-md5 aes128-cts-hmac-sha1-96 aes256-cts-hmac-sha1-96
allow_weak_crypto=true
[realms]
$kerberos_realm = {
kdc = $primary_directory_node_ip $ldap_master
admin_server = $primary_directory_node_ip $ldap_master
kpasswd_server = $primary_directory_node_ip $ldap_master
}
__EOF__
# Synchronize the time with the UCS system
$ ntpdate -bu $ldap_master
# Test Kerberos: kinit will ask you for a ticket and the SSH login to the Primary Directory Node should work with ticket authentication:
$ kinit Administrator
$ ssh -n Administrator@$ldap_master ls /etc/univention
# Destroy the kerberos ticket
$ kdestroy
1.5. Limitations of the Ubuntu domain integration#
It is currently not possible to change the user password at the LightDM login manager. Instead, the password can be changed via the kpasswd command after login or via the UMC module Change password.