Questions about The content of klist

[lizhong]

Hi all,
    I used klist to show the principals on my own Linux computer,and got the result below:
[root at gcnode029 gss-sample]# klist
Ticket cache: FILE:/tmp/krb5cc_0
Default principal: admin/admin at test.com

Valid starting     Expires            Service principal
08/24/06 09:50:02  08/24/06 19:50:02  krbtgt/test.com at test.com
        renew until 08/25/06 09:50:02
08/24/06 09:50:05  08/24/06 19:50:02  test/gcnode029 at test.com
        renew until 08/25/06 09:50:02


Kerberos 4 ticket cache: /tmp/tkt0
klist: You have no tickets cached

    What does the Default principal mean exactly? Does it mean the principal which stands for myself?
    What dose the Service principal mean exactly? Does it mean the principals which stand for the services I'm allowed to visit?
    How can I add one service principal into my ticket to get the privilege to visit it?

Thank you for any help!