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Produktlogo UCS Version 3.0

This guide describes the integration of Ubuntu into a UCS 3 domain. This configuration has been tested with Ubuntu 12.04 LTS and Kubuntu 12.04 LTS.

LDAP and SSL configuration

After Ubuntu has been installed, some of it's configuration files need to be modified. To simplify the setup, the default configuration of the UCS master domain controller should be copied to the Ubuntu system, for example:

# Become root
sudo bash

# Set the IP address of the UCS DC Master
export MASTER_IP=192.168.0.3

mkdir /etc/univention
ssh ${MASTER_IP} ucr shell | grep -v ^hostname= >/etc/univention/ucr_master
echo "master_ip=${MASTER_IP}" >>/etc/univention/ucr_master
. /etc/univention/ucr_master

echo "${MASTER_IP} ${ldap_master}" >>/etc/hosts

# Exit sudo bash
exit

The anonymous LDAP search is disabled by default in UCS 3. The Ubuntu client thus needs an account in the UCS 3 domain to gain read access to the LDAP directory.

# Become root
sudo bash

# Set some environment variables
. /etc/univention/ucr_master

# Download the SSL certificate
mkdir -p /etc/univention/ssl/ucsCA/
wget -O /etc/univention/ssl/ucsCA/CAcert.pem http://${ldap_master}/ucs-root-ca.crt

# Create an account and save the password
password="$(< /dev/urandom tr -dc A-Za-z0-9_ | head -c8)"
if [ "$version_version" = 3.0 ] && [ "$version_patchlevel" -lt 2 ]; then
    ssh root@${ldap_master} udm computers/managedclient create --position "cn=computers,${ldap_base}" \
        --set name=$(hostname) --set password="${password}"
else
    ssh root@${ldap_master} udm computers/ubuntu create --position "cn=computers,${ldap_base}" \
        --set name=$(hostname) --set password="${password}" \
        --set operatingSystem="$(lsb_release -is)" \
        --set operatingSystemVersion="$(lsb_release -rs)"
fi
echo "${password}" > /etc/ldap.secret

# Create ldap.conf
cat >/etc/ldap/ldap.conf <<__EOF__
TLS_CACERT /etc/univention/ssl/ucsCA/CAcert.pem
URI ldap://$ldap_master:7389
BASE $ldap_base
__EOF__

# Exit sudo bash
exit

System Security Services Daemon (SSSD)

SSSD provides a set of daemons to manage access to remote directories and authentication mechanisms.

# Become root
sudo bash

# Set some environment variables
. /etc/univention/ucr_master

# Install SSSD based configuration
DEBIAN_FRONTEND=noninteractive apt-get install sssd


# 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 = ${master_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 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        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 -n -a -p sss

# Start sssd
service sssd start

# Exit sudo bash
exit

The commands getent passwd and getent group should now also display all users and groups of the UCS 3 domain.

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

# Exit sudo bash
exit

During login users should also be added to some system groups, e.g.:

# 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 

# Exit sudo bash
exit

By default Ubuntu (12.04 LTS) 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
echo "greeter-show-manual-login=true" >>/etc/lightdm/lightdm.conf

# Optional: Disable the user selection at the login screen
echo "greeter-hide-users=true" >>/etc/lightdm/lightdm.conf

# Exit sudo bash
exit

With these settings the login for domain members should be possible after a restart of LightDM or a reboot.

Kerberos integration

Every UCS 3 domain provides a Kerberos domain. Since Kerberos relies heavily on DNS, the Ubuntu client should use a UCS system as the DNS server. The following steps show an example configuration for Kerberos:

# Become root
sudo bash

# Set some environment variables
. /etc/univention/ucr_master

# Install required packages
DEBIAN_FRONTEND=noninteractive apt-get install heimdal-clients

# Default krb5.conf
cat >/etc/krb5.conf <<__EOF__
[libdefaults]
    default_realm = $kerberos_realm
    kdc_timesync = 1
    ccache_type = 4
    forwardable = true
    proxiable = true

[realms]
$kerberos_realm = {
   kdc = $master_ip $ldap_master
   admin_server = $master_ip $ldap_master
}
__EOF__

# Stop and disable the avahi daemon
service avahi-daemon stop
sed -i 's|start on (|start on (never and |' /etc/init/avahi-daemon.conf

# Synchronize the time with the UCS system
ntpdate $ldap_master

# Test Kerberos
kinit Administrator

# This login shouldn't ask for a password
krsh Administrator@$ldap_master ls /etc/univention

# Destroy the kerberos ticket
kdestroy

# Exit sudo bash
exit

Limitations

The password change at the graphical display manager/login screen is not possible. The password can be changed via kpasswd or via the UMC module password change.

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