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| sidharth_bora |
 Posted: Tue Sep 04, 2007 10:23 pm Post subject: Incorrect data format received from host |
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Voyager
Joined: 24 Nov 2005
Posts: 87
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Hi Guys,
I am facing a weird issue. I have done a through searching in this forum/ibm site, and following are the conclusion for the issue of the FDC's being generated with the probe reason/id "Incorrect data format received from host "/CO052000 . The same probe reason is also in the error log.
we are on AIX 5.2, MQ5.3 CSD11 - no issues till date - We have connectivity to a Windows QM version 6.0
today morning the application team accessing the windows QM stated about the FDC being generated on their QM with the aforementioned probe id and reason. the incorrect data format they are getting is from our Aix server, and the sender channel went to retrying state.
After browsing i found :
if non mq application accesses and sends data to the MQ port, this fdc is generated, but we dont have any such application. Also this being intra flow, there's no question of snooping.
Also the application team confirmed that there's no message loss.but these messages are intermittent and FDC generated....
please advise. any pointers to the aforementioned issue is greatly appreciated. thanks all
regds
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| Nigelg |
| Posted: Tue Sep 04, 2007 10:46 pm Post subject: |
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Grand Master
Joined: 02 Aug 2004
Posts: 1046
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I think the FFST contains a dump of the first part of the data received at the port, so an analysis of this data might help determine where it is coming from.
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| sidharth_bora |
| Posted: Tue Sep 04, 2007 11:11 pm Post subject: |
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Voyager
Joined: 24 Nov 2005
Posts: 87
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Hi Nigelg,
thanks for your reply
The source of the data is already known to us. the point is to know why the channel went to retry state, and why the FDC was generated.
The appln team have confirmed that they processed all the messages.
But then why the error and the FDC ...
regds
Sid |
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| sidharth_bora |
| Posted: Wed Sep 05, 2007 12:26 am Post subject: |
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Voyager
Joined: 24 Nov 2005
Posts: 87
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Hi ALL / GM's
Please advise. I need to submit the report on the same at the earliest.
Anypointer/help/suggestion are welcome.
regds
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| Nigelg |
| Posted: Wed Sep 05, 2007 1:41 am Post subject: |
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Grand Master
Joined: 02 Aug 2004
Posts: 1046
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for goodness sake...
the FDC is generated because invalid data arrives at the port
the channel goes into retry because of the protocol error
the solution is to stop whatever is sending the invalid data form doing so
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| fjb_saper |
| Posted: Wed Sep 05, 2007 3:48 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Tell your network people that MQ does not like port sniffers and will produce the FDC every time a port sniffer attempts to check whether the MQ Listener Port will accept a connection....
The same happens if you do a telnet mqport to the target machine... 
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| sidharth_bora |
| Posted: Wed Sep 05, 2007 5:22 pm Post subject: |
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Voyager
Joined: 24 Nov 2005
Posts: 87
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the FDC is generated because invalid data arrives at the port
the channel goes into retry because of the protocol error
Hi Nigelg,
I have confirmed with the application team about the successful proeccssing of the messages, there is no loss of messages /data.
Tell your network people that MQ does not like port sniffers and will produce the FDC every time a port sniffer attempts to check whether the MQ Listener Port will accept a connection....
The same happens if you do a telnet mqport to the target machine
Also i know telnetting to the mq port and sending some data would create an DC with the same probe id and reason. This has been discussed un this forum itself.
The FDC log on the destination windows MQ manager shows our AIX source QM Ip. Does that mean that our AIX machine has an application connecting to MQ port on the windows machine.
I dont think, this is the only reason, the FDC is created with the same probe id and the reason.
Is there some thing related to service pack, CSD pack, fix pack.
regds
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| fjb_saper |
| Posted: Wed Sep 05, 2007 7:26 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Stop looking at MQ as the culprit. Start looking at other applications and more specifically network tools. The originating IP may be the same as the IP of a connected qmgr, but that does not mean that it is the other qmgr that's the cause of this...
Let's say that I know there's been trouble on the network between A and B.
Now I set a sniffer on B that will tell me the open ports on A and if port 1414 has problems on A (sniffer traffic going from B to A and hopefully traffic going back from A to B). This will produce FDC's in the A qmgr...
Enjoy
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