Debugging MQ client connection problems

I had lots of problems trying to get a client using TLS to connect to the queue manager, from set up errors, to unclear documentation.   It took me days to get my first channel set up.
IBM does not provide a program on midrange to format the GSKIT trace.  Someone suggested I use Wireshark  network packet analyser to monitor the traffic on the network.  I’ve given some examples of the handshake for TLS 12, TLS 13.

Below are some things you can do to check your set up is as you expect.

Review the error log

This is in /var/mqm/errors/AMQERR01.LOG
It does not provide all the information needed to identify the parameters used in the handshake, so you need to use the trace.

Turn on the MQ client trace

strmqtrc -e
start your program
endmqtrc -e

Format the trace

The client trace files are in /var/mqm/trace

  • cd /var/mqm/trace
  • dspmqtrc *.TRC

This will create several *.FMT files

Find the trace file for the connection

grep -F PeerName *.FMT

will list the file with the trace entries in it.  My file was  AMQ7232.0.FMT .

Check the channel name.

From the output of the grep -F PeerName *.FMT above, check the Channel Name: is what you expect? Check the remote IP address and port.  If you are using a CCDT it will take the first channel name which matches the queue manager.  This may not be the channel name you were expecting.    I had channels QMACLIENT and QMACLIENTTLS in the CCDT.   QMACLIENT was chosen instead of QMACLIENTTLS.

Check the mqclient.ini being used

grep -F mqclient.ini AMQ7232.0.FMT |grep -F FileName

Check the CCDT, (Channel Definition File) being used

grep -F ChannelDefinition AMQ7232.0.FMT

Adding stanza (ChannelDefinitionDirectory) length (19)
Adding stanza (ChannelDefinitionFile) length (10)
ChannelDefinitionDirectory = '/home/colinpaice/mq'
ChannelDefinitionFile = 'COLIN2.TAB'
Adding stanza (ChannelDefinitionFile) length (10)
Using ChannelDefinitionDirectory / MQCHLLIB value of /home/colinpaice/mq
Using ChannelDefinitionFile / MQCHLTAB value of RE.TAB
Adding stanza (ChannelDefinitionDirectory) length (19)
Adding stanza (ChannelDefinitionFile) length (10)
Using ChannelDefinitionDirectory / MQCHLLIB value of /home/colinpaice/mq
Using ChannelDefinitionFile / MQCHLTAB value of RE.TAB

The last entries show what was used.

Check the keystore being used

grep -Fi SSLKeyR *.FMT

Display the certlabl.

grep -Fi CertificateLabel *.FMT

It will display many records. They key ones are

  • MQCD CertificateLabel ‘rsaca256_client’
  • Saved CertificateLabel ‘rsaca256_client’

If these are missing certlabl has not been specified.

Display the channel definiton

Edit or browse the file and locate “CD “.

This will locate the MQCD (see the MQ documentation).

Interesting offsets in the CD are

  • 0x0000 Client channel name
  • 0x0060 Queue manager name
  • 0x00c0 IP address
  • 0x0698 Cipher Spec
  • 0x0780 TLSCertificate alias name in the client’s keystore.

Display Client Hello

You may have information about the TLS handshake.  This is called Client_hello, and Server_Hello.

Locate <client_hello> if found, it will have data like (some data removed).

client_version 
TLSV12
random ... 
session_id ... 
cipher_suites 
  tls_ri_scsv,tls_rsa_with_aes_128_cbc_sha256
compression_methods ...                              .
Extensions...
signature_algorithms 13
   rsa:sha512,rsa:sha384,rsa:sha256,rsa:sha224,...
server_name 
  qmaqclienttls.chl.mq.ibm.com
End of GSKit TLS Handshake Transcript

You need to understand the TLS handshake to fully understand this.

  • TLSV12 minimum level of TLS supported
  • cipher_suites these are what the client like
  • signature_algorithms  these are what the client will accept
  • server_name is “sni” information identifying the channel

What is my client connected to?

On a queue manager you an issue the DIS CHS(..)  all and get

SECPROT(TLSV12)
SSLCERTI(CN=SSCA256,OU=CA,O=SSS,C=GB)
SSLCIPH(TLS_RSA_WITH_AES_128_CBC_SHA256)
SSLPEER(SERIALNUMBER=01:79,CN=rsaca256,O=cpwebuser,C=GB,…)

I could not find a command to display the same information for the clients perspective.

You can look in the trace file for SSLCERTI for example

SSLCERTI(‘CN=SS,O=SSS,C=GB’)
SSLPEER(‘SERIALNUMBER=73:CB:2B:…,CN=SS,O=SSS,C=GB’)

This gives the server’s DN and Certificate issuer, and peer=subject.  As the peer has the same DN as the SSLCERTI this shows it is a self signed certificate.

7 thoughts on “Debugging MQ client connection problems

  1. Is it worth adding a step to grep your mqclient.ini file for ChannelDef? Looks like you’re showing that your mqclient.ini file contains multiple entries? This presumably would be easier to do than taking trace to discover the same problem?

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    1. I believe it is always the case that environment variables take precedence over the mqclient.ini file, but I can’t find it documented anywhere either. Some individual environment variables details that they specifically take precedence over their equivalent.

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