[Samba] smbd hanging because netbios-ssn TCP connexion not seen as down

Cedric Delfosse cedric.delfosse at linbox.com
Fri May 19 16:45:37 GMT 2006


(Samba 3.0.21c / Linux 2.4.27)

a smbd process was hanging on a file server since one day. This smbd 
process was locking some files on the server, and that was causing some 
share violation for a Windows user (well, that what I think).

I did a lsof on the smbd process, and I saw that the TCP netbios-ssn 
connection was still seen as established with the machine of the windows 
user that locked the files. The problem is that the machine was shut 
down at this moment since at least half an hour.

A strace showed me that smbd was looping on select calls, waiting for 
some data to read from the socket. Maybe that's why the smbd process was 
not exiting, and so still locking some files.

What can I do to avoid this kind of problem ?
In my smb.conf file, the "keepalive" option value was 300. Shouldn't 
this option be sufficient ?
How does keepalive work ? Does it work by sending some kind of 
"netbios-ssn echo packets" to the windows client ?
Does it work with all versions of Windows ?

If I set: socket options = SO_KEEPALIVE TCP_NODELAY, will this fix the 
problem when keepalive SAMBA option doesn't work ? (tcp_keepalive_time 
is 2 hours for Linux 2.4).

Best regards,

Cédric Delfosse                             Linbox / Free&ALter Soft
152, rue de Grigy - Technopole Metz                       57070 METZ
tél : 03 87 50 87 98                               http://linbox.com

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