Performance Problems ntlm_auth <-> Active Directory under heavy load

Matthew Newton mcn4 at
Thu Mar 19 22:44:11 CET 2015


[Please keep replies on-list]

On Thu, Mar 19, 2015 at 12:58:40PM +0000, tom greisch wrote:
> >Looks to me like you may have hit a different bug in winbind.  Try
> >running ntlm_auth from the command line and see if it gives the
> >same problem.
> if i use ntlm_auth from the command line a Backtrace is not
> logged. A Backtrace Log is also not generated if Freeradius does
> only few "sporadic" User Authentications. If the Count of
> Authentication increases i get a a lot of Backtraces logged. 

There are plenty of people running in this configuration, and this
is the first I've heard of winbind/ntlm_auth crashing and
producing backtraces. So it's likely something is odd about your

Have you tried Debian stable - it's possible there is a bug in the
Samba version in Jessie.

> ntlm_auth in freeradius not that ntlm_auth is the cause... sorry
> my english is really not perfect but i hope you understand what
> i mean...

Your English is good.

> >No, it doesn't say that, and you shouldn't do that. It will kill
> >performance. Use ntlm_auth if you can't use the new patches (which
> >aren't released yet anyway).
> yes of course i know that i will lose Performance but is it not
> better than a lot of Backtrace Logs or core dumps..

I think you should try a different version of Samba. Other people
don't see that. They _do_ see performance issues with too many
auths/second, which is, I believe, from the way people have to use
ntlm_auth at present, which isn't really a Samba issue.



Matthew Newton, Ph.D. <mcn4 at>

Systems Specialist, Infrastructure Services,
I.T. Services, University of Leicester, Leicester LE1 7RH, United Kingdom

For IT help contact helpdesk extn. 2253, <ithelp at>

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