[CentOS] LDAP / NSCD shadow caching problem

Thu Jul 15 18:29:43 UTC 2010
Brian Marshall <neorosbob at gmail.com>

On Jul 15, 2010, at 11:46 AM, Gary Greene wrote:

> On 7/15/10 9:15 AM, "Brian Marshall" <neorosbob at gmail.com> wrote:
>> Hi Todd,
>> Yes, I have already used authconfig to enable caching. If you have any
>> questions about my configs I have a forum post with more details up there
>> including the related ldap, and pam config files.
>> https://www.centos.org/modules/newbb/viewtopic.php?viewmode=flat&topic_id=2715
>> 3&forum=42
>> The problem still remains, when the LDAP server is offline there is no shadow
>> data cached so LDAP users can not authenticate on cached data despite caching
>> and local auth sufficient being enabled in authconfig .
>> So am I missing a package, config or something else somewhere.?
> Please don't top post, thanks.
> Now.... LDAP caching... Besides running a local LDAP slave on each machine,
> the only solution I know of is nsscache. What build problems have you had
> with it?
>> On Jul 15, 2010, at 9:52 AM, Todd Denniston wrote:
>>> Brian Marshall wrote, On 07/15/2010 11:37 AM:
>>>> Yes but I have worked in many organizations that use directory services for
>>>> authentication and my machines with them have always cached authentication
>>>> data so I can login if I'm not online. I can't expect laptop users to always
>>>> have a network connection. If Mac OS and Windows can manage to cache network
>>>> authentication for offline use, I can't believe that linux does not have
>>>> this capability.
>>>> Perhaps my wanting to cache my shadow data or use nscd for this purpose is
>>>> not the correct way to achieve this. But the only other well discussed
>>>> option I have found is nsscache which doesn't seem to work very well and
>>>> their library doesn't seem to install on centos 5. Unfortunately I'm way to
>>>> much of a hack C programmer to fix it, especially since they don't provide a
>>>> configure file.
>>>> So, assuming maybe we put the conversation of nscd shadow caching aside and
>>>> just talk about how to cache ldap data on a centos system so it can
>>>> authenticate users in the absence of a network. Creating local
>>>> passwd/group/shadow data is not an option.
>>>> Again, I can't stress this enough. I am convinced I am doing something wrong
>>>> or going about this the wrong way. I'm just not understanding how to either
>>>> fix the problem at hand or solve it another or proper way.
>>>> Any advice?
>>> authconfig -help
>>> authconfig --enablecache --update
>>> For some of the folks I work with, it works quite reliably, I on the other
>>> hand have had problems
>>> _because_ it caches the info.
>>>> Thanks 
>>>> Brian
>>>> On Jul 15, 2010, at 4:58 AM, Alexander Dalloz wrote:
>>>>>> The problem I am having is that shadow does not seem to get cached by
>>>>>> nscd. Here's how I have tracked this down.
>>>>> NSCD not caching shadow user credentials is a fact. There is nothing wrong
>>>>> with your configuration. NSCD just does not do what you seem to expect
>>>>> from it. You can't make it what you like to.
>>>>> If your LDAP server is gone, you will not be able to login. Run a replica
>>>>> server to avoid a single point of failure.
>>>>>> Brian
>>>>> Alexander
>>>>> _______________________________________________
>>>>> CentOS mailing list
>>>>> CentOS at centos.org
>>>>> http://lists.centos.org/mailman/listinfo/centos
>>>> _______________________________________________
>>>> CentOS mailing list
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>>>> http://lists.centos.org/mailman/listinfo/centos
>>> -- 
>>> Todd Denniston
>>> Crane Division, Naval Surface Warfare Center (NSWC Crane)
>>> Harnessing the Power of Technology for the Warfighter
>>> _______________________________________________
>>> CentOS mailing list
>>> CentOS at centos.org
>>> http://lists.centos.org/mailman/listinfo/centos
>> _______________________________________________
>> CentOS mailing list
>> CentOS at centos.org
>> http://lists.centos.org/mailman/listinfo/centos
> -- 
> Gary L. Greene, Jr.
> IT Operations
> Minerva Networks, Inc.
> Cell:  (650) 704-6633
> Phone: (408) 240-1239
> _______________________________________________
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Sorry about that top post.

nsscache seems to install ok but when I try to run the update it errors out on importing some other python file that didn't seem to get installed anywhere. It errors with this

[root at argentine ~]# nsscache update --full
Traceback (most recent call last):
  File "/usr/local/bin/nsscache", line 28, in ?
    from nss_cache import app
ImportError: No module named nss_cache

and here is /usr/local/bin/nsscache

 19 """Executable frontend to nss_cache."""
 21 __author__ = ('jaq at google.com (Jamie Wilkinson)',
 22               'vasilios at google.com (Vasilios Hoffman)')
 24 import logging
 25 import os
 26 import sys
 28 from nss_cache import app
 30 if __name__ == '__main__':
 31   nsscache_app = app.NssCacheApp()
 32   return_value = nsscache_app.Run(sys.argv[1:], os.environ)
 33   nsscache_app.log.info('Exiting nsscache')
 34   nsscache_app.log.debug('with value %d', return_value)
 35   sys.exit(return_value)

I do have a few things of matching name on the system but I'm not comfortable enough with the python environement to start monkeying around. It seems like an env var, path or prefix is not defined properly../usr/lib/libnss_cache.so

Locate finds these files (below) which are a result of the libnss-cache install.