20. User Authentication with Kerberos¶

User authentication via Active Directory (AD), also referred to as authentication through Kerberos, is supported through Ansible Tower.

To get started, first setup the Kerberos packages in the Tower system so that you can successfully generate a Kerberos ticket. To install the packages, use the following steps:

yum install krb5-workstation
yum install krb5-devel
yum install krb5-libs

Once installed, edit the /etc/krb.conf file, as follows, to provide the address of the AD, the domain, etc.:

[logging]
 default = FILE:/var/log/krb5libs.log
 kdc = FILE:/var/log/krb5kdc.log
 admin_server = FILE:/var/log/kadmind.log

[libdefaults]
 default_realm = WEBSITE.COM
 dns_lookup_realm = false
 dns_lookup_kdc = false
 ticket_lifetime = 24h
 renew_lifetime = 7d
 forwardable = true

[realms]
 WEBSITE.COM = {
  kdc = WIN-SA2TXZOTVMV.website.com
  admin_server = WIN-SA2TXZOTVMV.website.com
 }

[domain_realm]
 .website.com = WEBSITE.COM
 website.com = WEBSITE.COM

After the configuration file has been updated, you should be able to successfully authenticate and get a valid token. The following steps show how to authenticate and get a token:

[root@ip-172-31-26-180 ~]# kinit username
Password for username@WEBSITE.COM:
[root@ip-172-31-26-180 ~]#

Check if we got a valid ticket.

[root@ip-172-31-26-180 ~]# klist
Ticket cache: FILE:/tmp/krb5cc_0
Default principal: username@WEBSITE.COM

Valid starting     Expires            Service principal
01/25/16 11:42:56  01/25/16 21:42:53  krbtgt/WEBSITE.COM@WEBSITE.COM
  renew until 02/01/16 11:42:56
[root@ip-172-31-26-180 ~]#

Once you have a valid ticket, you can check to ensure that everything is working as expected from command line. To test this, make sure that your inventory looks like the following:

[windows]
win01.WEBSITE.COM

[windows:vars]
ansible_user = username@WEBSITE.COM
ansible_connection = winrm
ansible_port = 5986

You should also:

• Ensure that the hostname is the proper client hostname matching the entry in AD and is not the IP address.

• In the username declaration, ensure that the domain name (the text after @) is properly entered with regard to upper- and lower-case letters, as Kerberos is case sensitive. For Tower, you should also ensure that the inventory looks the same.

Now, running a playbook should run as expected. You can test this by running the playbook as the awx user.

Once you have verified that playbooks work properly, integration with Tower is easy. Generate the Kerberos ticket as the awx user and Tower should automatically pick up the generated ticket for authentication.