SSSD/Kerberos/LDAP Authentication

Install Required Packages

1. RHEL6: Install the following packages.
   1. # yum install sssd krb5-workstation samba-common authconfig oddjob oddjob-mkhomedir openldap-clients ipa-client sssd-common krb5-devel
2. RHEL7: Install the following packages
   1. # yum install sssd krb5-workstation samba-common authconfig oddjob oddjob-mkhomedir openldap-clients sssd-libwbclient sssd-tools ipa-client sssd-common krb5-devel
3. UBUNTU: Install the following packages
   1. $ sudo apt-get install krb5-user krb5-config samba sssd ntp nscd libpam-sss libnss-sss sssd-tools sssd-ad libpam-modules

Configure Kerberos

1. Gather the list of KDCs for the realm.
   1. # nslookup -type=SRV _kerberos._tcp.<domain in lowercase>

Output of previous command:

	Server:         <ip address>
	Address:        <ip address>#53
		
	_kerberos._tcp.<domain in lowercase>        service = 0 100 88 dc1.<domain in lowercase>.
	_kerberos._tcp.<domain in lowercase>        service = 0 100 88 dc2.<domain in lowercase>.
	_kerberos._tcp.<domain in lowercase>        service = 0 100 88 dc3.<domain in lowercase>.
	_kerberos._tcp.<domain in lowercase>        service = 0 100 88 dc4.<domain in lowercase>.	

1. Create a backup of the /etc/krb5.conf file.
   1. # cp -p /etc/krb5.conf{,.bak}
   2. Modify the /etc/krb5.conf file as follows, changes are highlighted in yellow.