[sudo-users] sudo doesn't prompt for password before failing

[Steve Kirkpatrick]

Hello,

I have installed LDAP-enabled sudo on two different Linux boxes and I
get the same behavior.  Hopefully someone has run across this before.

Site specifics:
<testuser at nisvn01> 16% uname -a
Linux nisvn01 2.6.18-128.1.6.el5 #1 SMP Tue Mar 24 12:10:27 EDT 2009
i686 i686 i386 GNU/Linux
<testuser at nisvn01> 17% sudo -V
Sudo version 1.6.9p20

sudo seems to be accessing LDAP OK since it knows what I am allowed to
do (BTW, /etc/sudoers is empty):
<testuser at nisvn01> 14% sudo -l
User testuser may run the following commands on this host:

LDAP Role: seRoot
  RunAs: (ALL)
  Commands:
    ALL

This is what happens when I try to su to root:

<testuser at nisvn01> 18% sudo su -

We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:

    #1) Respect the privacy of others.
    #2) Think before you type.
    #3) With great power comes great responsibility.

Sorry, try again.
Sorry, try again.
Sorry, try again.
sudo: 3 incorrect password attempts
<testuser at nisvn01> 19%

You can see that it never prompts for the password.  What could cause
that behavior?  This same version of sudo works fine on my Solaris
servers using the same LDAP servers.

Any suggestions are appreciated.

Thanks,
Steve.