Installation guide

142 Chapter 10. Kerberos

Once you have completed the steps listed above, the Kerberos server should be up and running. Next,

we will set up a Kerberos client.

10.7. Conﬁguring a Kerberos 5 Client

Setting up a Kerberos 5 client is less involved than setting up a server. At minimum, install the client

packages and provide each client with a valid krb5.conf conﬁguration ﬁle. Kerberized versions of

rsh and rlogin will also require some conﬁguration changes.

1. Be sure that you have time synchronization in place between the Kerberos client and KDC.

See Section 10.6 for more information. In addition, verify that DNS is working properly on the

Kerberos client before conﬁguring the Kerberos client programs.

2. Install the krb5-libs and krb5-workstation packages on all of the client machines. You

must supply a version of /etc/krb5.conf for each client; usually this can be the same

krb5.conf used by the KDC.

3. Before a workstation in the realm can allow users to connect using kerberized rsh and rlogin,

that workstation will need to have the xinetd package installed and have its own host principal

in the Kerberos database. The kshd and klogind server programs will also need access to the

keys for their service’s principal.

Using kadmin, add a host principal for the workstation on the KDC. The instance in this case

will be the hostname of the workstation. You can use the -randkey option to kadmin’s ad-

dprinc command on the KDC to create the principal and assign it a random key:

addprinc -randkey host/blah.example.com

Now that you have created the principal, you can extract the keys for the workstation by running

kadmin on the workstation itself , and using the ktadd command within kadmin:

ktadd -k /etc/krb5.keytab host/blah.example.com

In order to use the kerberized versions of rsh and rlogin, you must enable klogin, eklogin,

and kshell.

4. Other kerberized network services will need to be started. To use kerberized telnet, you must

enable krb5-telnet.

To provide FTP access, create and extract a key for a principal with a root of ftp, with the

instance set to the hostname of the FTP server. Then enable gssftp.

The IMAP server included in the imap package will use GSS-API authentication using Kerberos

5 if it ﬁnds the proper key in /etc/krb5.keytab. The root for the principal should be imap.

The CVS gserver uses a principal with a root of cvs and is otherwise identical to a pserver.

10.8. Additional Resources

For more information on Kerberos, refer to the following resources.

1. Refer to the chapter titled Controlling Access to Services in the Ofﬁcial Red Hat Linux Customization Guide

for details on enabling services.