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TCP Socket listening but does not send ACK+SYN

Posted on 2006-11-30
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Last Modified: 2013-11-29
Hello,

I have a server that we are running several QA tests on. One test involves a java client that connects to a java server (all on the same machine). If I do a netstat , I can see that the Java server is running and listening on port 30041. When i kick off the test, I can see the client attempt a connection to the server's socket. The client socket sits there in the SYN SENT state but never appears to receive an ACK+SYN from the server socket. The client process eventually gives up and dies. Does anyone have any suggestions on how to troubleshoot this problem on a Linux box? The firewall and SELinux are turned off. What logs should I be looking at? I tried running TCPDUMP but that did not provide me with any useful info. Any help would be appreciated.
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Question by:tmelo49
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7 Comments
 
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Accepted Solution

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Trilotech earned 750 total points
ID: 18047560
Do you have multiple IP Addresses? Perhaps the client software is trying the wrong address (if you are using multiple addresses). This could mean a DNS issue if you are using hostnames.
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Author Comment

by:tmelo49
ID: 18047705
Here is the tricky part that i forgot to mention, this particular server is actually a virtual OS through VMWare, but only has 1 IP and the DNS record appears fine (reverse lookup too). Even though it is a virtual OS, it functions as a completely independent OS. I really dont think the fact that it is a virtual OS is the cause of the problem. All other server/client processes talk just fine.
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Expert Comment

by:Trilotech
ID: 18047809
Is it totally self contained in VMWare? Or is it an IP address that is accessible from the rest of your LAN?

If it is self contained and all other functions are working related to DNS and other networking services, then I would think the problem would be within the software. Perhaps a configuration error?

Check the documentation and perhaps contact the software developer.
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Author Comment

by:tmelo49
ID: 18047834
It is an IP that is accessible from the rest of the network.
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Author Comment

by:tmelo49
ID: 18048488
I figured out the problem......incorrect hosts file entry for localhost .
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Author Comment

by:tmelo49
ID: 18048511
Thanks Trilotech. You put me on the right path.
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Expert Comment

by:Trilotech
ID: 18048524
No problem. Glad you got it!
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