On 11/09/2010 04:43 AM, Volker Lendecke wrote:
On Mon, Nov 08, 2010 at 09:23:06AM -0500, Andy Liebman wrote:
And now I have this case.

I would appreciate the opinion of the Samba.org folks.  Does it make
sense that constant bombardment of a Samba server with failed
connection attempts could cause the whole server to crash?
No, definitely not. We could certainly talk about increasing
the debug level of that message from 0 to 1, so that it does
not appear in syslog.

Volker

I have another case today of constant failed connection attempts crashing a Samba server. It's the same thing as the previous time -- a workstation continually trying to access a share using a share name that's missing the last character. As it happens, without the last character, the share name being requested ends with an underscore character ("_"). Don't know if that is relevant.

We are writing a simple Windows program to reproduce the failed connections and to see if we can bring down our own Samba servers. :)

You suggested previously this might be a kernel bug, or that the failed attempts might be using up some scarce resource (memory? open files? what did you have in mind?) Assuming we can reproduce this issue, what do you suggest would be the best way to start debugging it? I don't think running Samba with more logging or debugging is going to help. Suppose we can continually run vmstat and write the results to a log file. Anything else you can think of?

FYI, I ran into another developer this week who had the same experience I had a few years back when the Google desktop indexer came out. If Google indexer was trying to index a Samba share and it was logging in with the wrong credentials, it would try to log in thousands of times per minute and bring down the Samba servers after a short period of time. Getting rid of the Google indexer made the crashes go away.

Andy
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