Installation and configuration of MIT Kerberos on Ubuntu

Kerberos is a central authentication protocol used to verify users, hosts and services using kerberos database. Kerberos database contains the entries called principals,which consists of principal names, secret keys, key aging information and Kerberos-specific data. User can access these principal from anywhere in the realm. Each realm contain one Key Distribution center and many slaves.User input is authenticated against the Kerberos database. In successful authentication, the KDC ("Key Distribution Center") will issue users a "confirmation", called the TGT ("Ticket-Granting Ticket"). You can find more information about kerberos from following links

[1] http://en.wikipedia.org/wiki/Kerberos_(protocol)
[2] http://web.mit.edu/kerberos/#what_is
[3] http://www.kerberos.info/

Environment:
Operating System: Ubuntu 10.04 Lucid Lynx 64 bit Edition
Kerberos : MIT Kerberos V5

MIT Kerberos, an implementation of Kerberos, will be used to authenticate users

Installation

Step 1: Install Key Distribution Center(KDC) and administration server 

sudo apt-get install krb5-{admin-server,kdc}

It will install master kdc and admin server , we can configure multiple slave kdc under a single master kdc. KDC installation will ask following questions
1. Default Kerberos version 5 realm?
We can gave any ASCII string as realm but conventionally use the upper case version of domain name 2. Kerberos4 compatibility mode to use? 
Give it as 'none'
3.What are the Kerberos servers for your realm?
Fully qualified domain name of kerberos server
4.What is the administrative server for your realm?
Fully qualified domain name of kerberos server 

Step 2:Create new realm use 'krb5_relam'

Use the command krb5_newrealm in the terminal

krb5_newrealm

The command will ask about the master password(don't forgot this) and create the realm using the name as define in the previous steps

Step 3:Restart Administrative server and key distribution center

sudo invoke-rc.d krb5-admin-server restart
sudo invoke-rc.d krb5-kdc restart

Step 4 :Initial Test

To just quickly test the installation, we will use the 'kadmin.local' database administration program. Start kadmin.local, then type 'listprincs'. That command should print out the list of principals. For example

sudo kadmin.local
Authenticating as principal root/admin@TEST.COM with password.

kadmin.local:  listprincs

K/M@TEST.COM
kadmin/admin@TEST.COM
kadmin/changepw@TEST.COM
kadmin/history@TEST.COM
krbtgt/TEST.COM@TEST.COM
kadmin.local: quit

'kadmin.local' work only in kerberos administration center\

Step 5:Access Rights

Edit /etc/krb5kdc/kadm5.acl file, and uncomment '*/admin *' line Enter into 'kadmin.local' and add policy for root user 'addprinc root/admin' For example

sudo kadmin.local
Authenticating as principal root/admin@TEST.COM with password.

kadmin.local:  addprinc root/admin

WARNING: no policy specified for root/admin@TEST.COM; defaulting to no policy
Enter password for principal "root/admin@TEST.COM": PASSWORD
Re-enter password for principal "root/admin@TEST.COM": PASSWORD
Principal "root/admin@TEST.COM" created.

kadmin.local:  quit

Restart Administrative server and key distribution center(Refer step 3) Test the new step using 'kadmin'. Kadmin as root/admin using

kadmin -p root/admin

If the configuration is correct, it will ask for password

Step 6: Obtaining a Kerberos Ticket 

Commands 

klist -5 -List the cached ticket 

kinit -to obtain ticket for current user 

Step 7:Installing Kerberized Services Kerberized service is need to authenticate with kerberos.

sudo apt-get install krb5-rsh-server 
sudo update-rc.d openbsd-inetd defaults
sudo invoke-rc.d openbsd-inetd restart

Step 8:Connecting to a Kerberos Server 

Install krb5-clients and krb5-user in each host, where we want to use kerberos authentication.

sudo apt-get install krb5-clients krb5-user

It will ask for kerberos administration and key distribution center details

References
[1] http://www.debian-administration.org/articles/570
[2] http://web.mit.edu/kerberos/krb5-1.8/krb5-1.8.1/doc/krb5-install.html
[3] http://techpubs.spinlocksolutions.com/dklar/kerberos.html