Integrate an Ubuntu Virtual Machine with Active Directory for Smart Card Redirection

To support smart card redirection on Ubuntu desktops, integrate the base virtual machine (VM) with an Active Directory (AD) domain using the Samba and Winbind solutions.

Use the following procedure to integrate an Ubuntu VM with an AD domain for smart card redirection.

Some examples in the procedure use placeholder values to represent entities in your network configuration, such as the DNS name of your AD domain. Replace the placeholder values with information specific to your configuration, as described in the following table.


Placeholder Value	Description
dns_IP_ADDRESS	IP address of your DNS name server
mydomain.com	DNS name of your AD domain
MYDOMAIN.COM	DNS name of your AD domain, in all capital letters
MYDOMAIN	DNS name of the workgroup or NT domain that includes your Samba server, in all capital letters
ads-hostname	Host name of your AD server
ads-hostname.mydomain.com	Fully qualified domain name (FQDN) of your AD server
mytimeserver.mycompany.com	DNS name of your NTP time server
AdminUser	User name of the VM administrator

Procedure

On the Ubuntu VM, define the host name of the VM by editing the /etc/hostname configuration file.
Configure DNS.
1. Add the DNS server name and IP address to the /etc/hosts configuration file.
2. Add your DNS name server's IP address and the DNS name of your AD domain to the /etc/network/interfaces configuration file, as shown in the following example.
```
dns-nameservers dns_IP_ADDRESS
dns-search mydomain.com
```
Install the resolvconfig package.
1. Run the installation command.
```
apt-get install -y resolvconf
```
  Allow the system to install the package and reboot.
2. Verify your DNS configuration in the /etc/resolv.conf file, as shown in the following example.
```
cat /etc/resolv.conf
…
nameserver dns_IP_ADDRESS
search mydomain.com
```
Configure network time synchronization.
1. Install the ntpdate package.
```
apt-get install -y ntpdate
```
2. Add the NTP server information to the /etc/systemd/timesyncd.conf configuration file, as shown in the following example.
```
[Time]
NTP=mytimeserver.mycompany.com
```
Restart the NTP service.
```
sudo service ntpdate restart
```
Install the required AD join packages.
1. Run the installation command.
```
apt-get install -y samba krb5-config krb5-user winbind libpam-winbind
    libnss-winbind
```
2. At the installation prompt asking for the default Kerberos realm, enter the DNS name of your AD domain in capital letters (for example, MYDOMAIN.COM). Then select Ok.

Edit the /etc/krb5.conf configuration file, as shown in the following example.

[libdefaults]
      dns_lookup_realm = false
      ticket_lifetime = 24h
      renew_lifetime = 7d
      forwardable = true
      rdns = false
      default_realm = MYDOMAIN.COM
      default_ccache_name = KEYRING:persistent:%{uid}

[realms]
      MYDOMAIN.COM = {
            kdc = ads-hostname.mydomain.com
            admin_server = ads-hostname.mydomain.com
            default_domain = ads-hostname.mydomain.com
            pkinit_anchors = FILE:/etc/pki/nssdb/certificate.pem
            pkinit_cert_match = <KU>digitalSignature
            pkinit_kdc_hostname = ads-hostname.mydomain.com
      }

[domain_realm]
      .mydomain.com = MYDOMAIN.COM
      mydomain.com = MYDOMAIN.COM

To verify the Kerberos certification, run the following commands.

kinit Administrator@MYDOMAIN.COM

klist

Verify that the commands return output similar to the following example.

Ticket cache: FILE:/tmp/krb5cc_0
Default principal: Administrator@MYDOMAIN.COMValid starting        Expires                Service principal
2019-05-27T17:12:03   2019-05-28T03:12:03    krbtgt/MYDOMAIN.COM@MYDOMAIN.COM
        renew until 2019-05-28T17:12:03

Edit the /etc/samba/smb.conf configuration file, as shown in the following example.

[global]
      workgroup = MYDOMAIN  
      realm = MYDOMAIN.COM
      password server = ads-hostname.mydomain.com
      security = ads
      kerberos method = secrets only
      winbind use default domain = true
      winbind offline logon = false 
      template homedir =/home/%D/%U
      template shell = /bin/bash 
      client use spnego = yes
      client ntlmv2 auth = yes
      encrypt passwords = yes
      passdb backend = tdbsam
      winbind enum users = yes
      winbind enum groups = yes
      idmap uid = 10000-20000
      idmap gid = 10000-20000

Join the AD domain, and check the integration.
1. Run the AD join commands.
```
net ads join -U AdminUser@mydomain.com
systemctl stop samba-ad-dc
systemctl enable smbd nmbd winbind
systemctl restart smbd nmbd winbind
```
2. Modify the /etc/nsswitch.conf configuration file, as shown in the following example.
```
passwd:    compat systemd winbind
group:     compat systemd winbind
shadow:    compat
gshadow:   files
```
3. To check the results of the AD join, run the following commands and verify that they return the correct output.
```
wbinfo -u

wbinfo -g
```
4. To check the Winbind Name Service Switch, run the following commands and verify that they return the correct output.
```
getent group|grep 'domain admins'

getent passwd|grep 'ads-hostname'
```
Enable all PAM profiles.
```
pam-auth-update
```
In the PAM Configuration screen, select all the PAM profiles, including Create home directory on login, and then select Ok.
On Ubuntu 16.04, enable the user switch in the login screen. Modify the /usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf file as shown in the following example.
```
user-session=ubuntu
greeter-show-manual-login=true
```

What to do next

Set Up Smart Card Redirection on an Ubuntu Virtual Machine