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| Issues with reverse DNS lookup in Windows 10 |
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| jamesb |
 Posted: Fri Oct 25, 2019 6:51 am Post subject: Issues with reverse DNS lookup in Windows 10 |
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Novice
Joined: 09 Mar 2008
Posts: 17
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Hi all, Does anyone here still use rfhutilc and, in particular, on Windows 10 desktop? The scenario is this: We are running an MQ v8 server on Linux and our support team have been using rfhutilc on Windows 7 to put/get/move messages, etc. That was working fine using the DNS name of our MQ server to connect in the connection string of the form
CHANNEL_NAME/TCP/HOST_NAME.com(Port)
in the first box, Queue manager connection.
They've now 'upgraded' to Windows 10 and it no longer works with the DNS name in the connection string and we have to use the IP instead. With DNS it fails with 'host not available', 2538. Doing a bit of reading around it sounds like the DNS lookup/reverse DNS lookup may not be working correctly in windows 10 and when I did a client trace it looked like it was confirming a failure in the DNS lookup.
RSESS:000001 xcsIsEnvironment[AMQ_NO_IPV6] = FALSE
RSESS:000001 ----------} xcsIsEnvironment (rc=OK)
RSESS:000001 ----------{ cciTcpResolveHostname
RSESS:000001 Hostname: 'mycorrecthostname.com'
RSESS:000001 getaddrinfo(): AF_INET & AI_NUMERICHOST: rc=11001 errno=2
RSESS:000001 getaddrinfo(): AF_INET6: rc=11001 errno=2
RSESS:000001 getaddrinfo(): AF_INET: rc=11001 errno=2
RSESS:000001 serv_addr4
RSESS:000001 Data:-
RSESS:000001 0x00EFC400 00 00 20 77 00 00 00 00 00 00 00 00 00 00 00 00 : .. w............
RSESS:000001 serv_addr6
RSESS:000001 Data:-
RSESS:000001 0x00EFC42C 00 00 20 77 00 00 00 00 00 00 00 00 00 00 00 00 : .. w............
RSESS:000001 0x00EFC43C 00 00 00 00 00 00 00 00 00 00 00 00 : ............
RSESS:000001 ----------}! cciTcpResolveHostname (rc=rrcE_HOST_NOT_AVAILABLE)
There's definitely no issue with the correct hostname I am using so no typo error. This was with an old version of rfhutilc as well as the latest version I downloaded from git. The trace runs fine on windows 7 and the DNS is resolved correctly. However, we have no issue using the MQ v8 Explorer from Windows 10 with the DNS name to connect to our queue managers and it resolves it with no issues. Can anyone point me in the right direction here to understand what the issue is running from rfhutilc on win10 and if it's 'fixable'?
Thanks, James. |
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| HubertKleinmanns |
| Posted: Fri Oct 25, 2019 7:15 am Post subject: |
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Shaman
Joined: 24 Feb 2004
Posts: 732
Location: Germany
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I don't think, that "rfhutilc" or the MQ Explorer have implemented a DNS resolution functionality. This is should have been done by Windows. May be, that there are several system calls, to resolve DNS names, and "rfhutilc" and MQ Explorer use different ones. But nevertheless you should address this to the Windows people.
Possibly as a work-around you could add the names to a "hosts" file, which you should find in:
| Code: |
| C:\Windows\System32\drivers\etc |
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Hubert |
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| hughson |
| Posted: Fri Oct 25, 2019 2:27 pm Post subject: |
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Padawan
Joined: 09 May 2013
Posts: 1959
Location: Bay of Plenty, New Zealand
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Neither rfhutil, nor MQ Explorer are responsible for the DNS lookup (FYI, your title is misleading, this is not reverse lookup). The MQ Client is making the call to resolve the hostname into an IP address. The difference between rfhutil and MQ Explorer is likely the difference between the call to resolve a hostname in 'C' versus in Java.
Try, for example, running amqsputc with an MQSERVER environment variable set to use the hostname rather than the IP address - should see same failure.
The error shown in your trace, 11001 is WSAHOST_NOT_FOUND.
What is the result of:-
| Code: |
| nslookup mycorrecthostname.com |
Cheers,
Morag
_________________
Morag Hughson @MoragHughson
IBM MQ Technical Education Specialist
Get your IBM MQ training here!
MQGem Software |
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| fjb_saper |
| Posted: Fri Oct 25, 2019 4:56 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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As you are dealing with windows and dns lookup, I strongly encourage you to also do a ping -a hostname. We had a problem where IPV6 was not configured, still active and all hostnames came back to ::1 ! Thank you very much!
Disabling IPV6 on the box solved the problem, and the ping came back with the right IPV4 address.
Have fun 
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MQ & Broker admin |
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| PeterPotkay |
| Posted: Sat Oct 26, 2019 4:12 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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Also, always fully qualify your names as a best practice.
Instead of calling:
myservername
Call:
myservername@yourdomainname.com (or however your company fully qualifies their DNS names)
For whatever reason that I not felt worth researching any further, my work laptop sometimes (not always) stops resolving some (not all) DNS names that are not fully qualified. I just always fully qualify them and no longer have this issue.
_________________
Peter Potkay
Keep Calm and MQ On |
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