Connection hangs...

David Lee T.D.Lee at
Thu Mar 2 17:05:47 GMT 2000

On Fri, 18 Feb 2000, David Lee wrote:

> In problem-fixing, the "nicest" problems are those reproducible on demand.
> Alas, this one is not nice.
> System: Samba 2.0.6 on Solaris 2.7 (also see similar on Solaris 2.6).
> Symptom (user perspective):  PC suddenly, spontaneously freezes and
> eventually the connection times out. 
> Symptom (log file): 
>    [2000/02/15 09:27:30, 0] ../lib/util_sock.c:read_socket_data(474)
>      read_socket_data: recv failure for 4. Error = Connection timed out
> We have several hundred simultaneous connections from our NT-based
> classrooms to about four Solaris servers.  All usually works very well. 
> The above events are therefore relatively rare, but nevertheless still add
> up to several occurences per day. 
> Naturally, I'm not looking forward to debugging this one.  So just before
> I start, is this a "known" problem?  Any fixes, workarounds?  Might it be
> addressed in pre-2.0.7 (whose "WHATSNEW.txt" is not yet made)?  Any hints?

We have done further work and eventually tracked it down.  Samba is
innocent, the problem lies "in the network", beyond the control of Samba.
In that sense, you good Samba folk can regard the problem as null and
closed.  (For us, the problem is very real and lives on...) 

[ For the curious: The PCs are separated from the server by a router.  So
in normal operation, ARP/RARP exchanges will ensure that the PC learns an
arp entry that maps the server-IP-address to the router-MAC-address.  When
this problem strikes, we find the arp entry has the server's own MAC
address which has somehow leaked throught our ancient, flaky, router. (The
usual "shouldn't happen" thing that we all know and love.)  Anyway I have
passed this problem to the network people. ]


:  David Lee                                I.T. Service          :
:  Systems Programmer                       Computer Centre       :
:                                           University of Durham  :
:            South Road            :
:                                           Durham                :
:  Phone: +44 191 374 2882                  U.K.                  :

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