Configuring Kerberos Network Application Servers

Network application servers are hosts that provide access using one or more of the following network applications: ftp, rcp, rlogin, rsh, ssh, and telnet. Only a few steps are required to enable the Kerberos version of these commands on a server.

How to Configure a Kerberos Network Application Server

This procedure uses the following configuration parameters:

• Application server = boston

• admin principal = kws/admin

• DNS domain name = example.com

• Realm name = EXAMPLE.COM

Before You Begin

This procedure requires that the master KDC has been configured. To fully test the process, several Kerberos clients must be configured.

1. (Optional) Install the NTP client or another clock synchronization mechanism.

   See Synchronizing Clocks Between KDCs and Kerberos Clients for information about NTP.

2. Add principals for the new server and update the server's keytab.

   The following command reports the existence of the host principal:

   boston # klist -k |grep host
   4 host/boston.example.com@EXAMPLE.COM
   4 host/boston.example.com@EXAMPLE.COM
   4 host/boston.example.com@EXAMPLE.COM
   4 host/boston.example.com@EXAMPLE.COM

   If the command does not return a principal, then create new principals using the following steps.

   How to use the Graphical Kerberos Administration Tool to add a principal is explained in How to Create a New Kerberos Principal. The example in the following steps shows how to add the required principals using the command line. You must log in with one of the admin principal names that you created when configuring the master KDC.

   boston # /usr/sbin/kadmin -p kws/admin
   Enter password: <Type kws/admin password>
   kadmin: 

   1. Create the server's host principal.

      kadmin: addprinc -randkey host/boston.example.com
      Principal "host/boston.example.com" created.
      kadmin: 

   2. Add the server's host principal to the server's keytab.

      If the kadmin command is not running, restart it with a command similar to the following: /usr/sbin/kadmin -p kws/admin

      kadmin: ktadd host/boston.example.com
      Entry for principal host/boston.example.com with kvno 3, encryption type AES-256 CTS mode
                with 96-bit SHA-1 HMAC added to keytab WRFILE:/etc/krb5/krb5.keytab.
      Entry for principal host/boston.example.com with kvno 3, encryption type AES-128 CTS mode
                with 96-bit SHA-1 HMAC added to keytab WRFILE:/etc/krb5/krb5.keytab.
      Entry for principal host/boston.example.com with kvno 3, encryption type Triple DES cbc
                mode with HMAC/sha1 added to keytab WRFILE:/etc/krb5/krb5.keytab.
      Entry for principal host/boston.example.com with kvno 3, encryption type ArcFour
                with HMAC/md5 added to keytab WRFILE:/etc/krb5/krb5.keytab.
      Entry for principal host/boston.example.com with kvno 3, encryption type DES cbc mode
                with RSA-MD5 added to keytab WRFILE:/etc/krb5/krb5.keytab.
      kadmin:

   3. Quit kadmin.

      kadmin: quit