[Samba] winbind causes Linux to lockup when connectivity to AD is lost (subject line edited for clarity)

Clayton Hill admin at ateamonsite.com
Sun Oct 18 17:49:01 MDT 2009

Thanks for confirming my config is good. I already know about the old 
problem with SSH and reverse DNS lookups. That actually takes about 5 
minutes or less to log in, with this issue be prepared to wait almost an 
hour if it even works. Similar but not the same issue.
Please, to get an understanding of this problem do the following steps 
to reproduce this problem.

SUSE 11.0
Samba 3.2
Join windows 2003 AD domain (with 40,000 objects) using       net ads join
Take domain controller offline.

Try to log in LOCALLY as ROOT to your console on your domain member 
linux box. Do not even bother to log in as any samba user of do ANYTHING 
samba related.
Watch as it takes more time than bearable (I am talking MORE THAN 20 
minutes!) to0 log in to the LOCAL TERMINAL
attempt to do the same with ssh
if you are already logged in before you do this test as root LOCALLY TTY 
then try and run simple commands such as:   top,ls,ps,man etc etc

After seeing the problem clearly simply do this to become unstuck:
killall winbindd
service winbind stop

have a lot of fun.



Matthew J. Salerno wrote:
> Your  /etc/nsswitch.conf looks correct to me.  For services like ssh, you should just disable ptr lookups (VerifyReverseMapping no).  Regarding winbind, do you have any services or processes running on the box as a domain user?  Perhaps there is a timeout setting for krb and winbind.  I don't recall seeing one for winbind, but I would imagine that there is one for kerberos.  Have you bumped up the debugging and purposefully caused an ad failure (ifdown or bad route) ?  Have you had the console open and watched top to see if it's a processes consuming to much cpu?  What kind of troubleshooting have you done?  and what are the results?
> ----- Original Message ----
> From: "admin at ateamonsite.com" <admin at ateamonsite.com>
> To: admin at ateamonsite.com
> Cc: samba at lists.samba.org; Jeremy Allison <jra at samba.org>
> Sent: Fri, October 16, 2009 3:59:45 PM
> Subject: Re: [Samba] winbind causes Linux to lockup when connectivity to AD is lost (subject line edited for clarity)
> Ok I am not hearing replies back - I dont want this issue to be swept under
> the rug. 
> It has been a issue for me since SuSE 10.1 + samba-3.0.30-0.1.112 even..
> I know now that the commands I was telling you all access UN/PW info such
> as LS or MAN etc, to see if you have permission to run them? IDK I am
> guessing.
> BUT - if winbind is really caching and the connection is lost, then this
> should be a non-issue as you say.
> Well here is my nsswitch.conf:
> cat /etc/nsswitch.conf
> passwd: compat winbind
> group:  compat winbind
> networks:       files dns
> services:       files
> protocols:      files
> rpc:    files
> ethers: files
> netmasks:       files
> netgroup:       files
> publickey:      files
> bootparams:     files
> automount:      files
> aliases:        files
> hosts:  files dns
> shadow: compat
> Isn't this set up right? ;-)
> So, famously when DNS is down, crap like SSH and NFS take unreasonable
> amounts of time and cause system hangs in linux. This is what I've been
> told, and I can accept that.
> Since DNS is hosted on the AD server, when that server goes down, SSH, and
> even local login hang for extremely long amounts of time - im talking more
> than 10 minutes... then fail.
> In Windows (im sorry Im about to compare 2 operating systems) this is a non
> issue and you can use the machine even if the networking is hosed or you
> cant talk to the AD.
> So.......
> BUMP! :-)
> On Wed, 14 Oct 2009 16:51:10 -0600, <admin at ateamonsite.com> wrote:
>> Hopefully that isn't a bad thing! haha 
>> Thanks! 
>> On Wed, 14 Oct 2009 15:44:54 -0700, Jeremy Allison <jra at samba.org> wrote:
>>> On Wed, Oct 14, 2009 at 04:02:41PM -0600, admin at ateamonsite.com wrote:
>>>> Hi Jeremy,
>>>>> Sorry, didn't look too closely at your winbindd issue.
>>>>> winbindd will cache all information to allow disconnected
>>>>> operation (we made this work perfectly at SuSE), so there
>>>>> certainly shouldn't be a problem with a loss of connection to a DC.
>>>> I am sorry to report that I am in fact using SuSE, and this problem is
>>>> very
>>>> easy to reproduce if I power off my AD domain, then wait (I guess) 10
>>>> minutes - then try and ssh to my Linux box. There is no way to log into
>>>> the
>>>> box. 
>>> Ok, then I'm going to hand you over to the SuSE Samba Team
>>> maintainers on this list (sorry :-).
>>> Jeremy.

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