samba - Jun 2006 - nmblookup receives response, but doesn't show it

Hi folks,

	I find that nmblookup seems to be receiving 
responses to name queries, but ignoring them.  Here's what's
happening:

	# nmblookup somehost
	querying somehost on x.y.255.255
	name_query failed to find name somehost

But watching the transaction with ethereal on the local
host, I see that:

1.  nmblookup on local udp port nnnn (some random number above 1024) 
    sends an nbns packet to udp port 137 on the broadcast address
2.  "somehost" immediately responds with an appropriate packet
    from port 137 on somehost, directed at port nnnn on the local host.
    This packet contains the correct IP address of somehost.

Nonetheless, nmblookup acts as though it never received anything,
and retries the request two more times before giving up.  (Each of
the additional tries also results in a correct response from
somehost.)

	iptables isn't the culprit, since I'm allowing anything
with a dport or sport of udp 137.  (Also, I wouldn't even
be seeing these packets with ethereal if they were blocked.)

	What's going on here?  It looks like nmblookup is
just choosing to ignore the responses.

	FWIW: samba-3.0.20, Linux 2.6.12

	Thanks in advance for any suggestions.

						Bryan
-- 
=======================================================================Bryan
Wright              |"If you take cranberries and stew them like
Physics Department        | applesauce, they taste much more like prunes
University of Virginia    | than rhubarb does."  --  Groucho 
Charlottesville, VA  22901|			
(434) 924-7218            |         bryan@virginia.edu
========================================================================

On Mon, Jun 12, 2006 at 08:27:52PM +0000, Bryan K. Wright
wrote:
> Hi folks,
> 
> 	I find that nmblookup seems to be receiving 
> responses to name queries, but ignoring them.  Here's what's
> happening:
> 
> 	# nmblookup somehost
> 	querying somehost on x.y.255.255
> 	name_query failed to find name somehost
> 
> But watching the transaction with ethereal on the local
> host, I see that:
> 
> 1.  nmblookup on local udp port nnnn (some random number above 1024) 
>     sends an nbns packet to udp port 137 on the broadcast address
> 2.  "somehost" immediately responds with an appropriate packet
>     from port 137 on somehost, directed at port nnnn on the local host.
>     This packet contains the correct IP address of somehost.
> 
> Nonetheless, nmblookup acts as though it never received anything,
> and retries the request two more times before giving up.  (Each of
> the additional tries also results in a correct response from
> somehost.)
> 
> 	iptables isn't the culprit, since I'm allowing anything
> with a dport or sport of udp 137.  (Also, I wouldn't even
> be seeing these packets with ethereal if they were blocked.)
> 
> 	What's going on here?  It looks like nmblookup is
> just choosing to ignore the responses.
You can always check by running under gdb and seeing
if it wakes up on the response. 

Jeremy