Solved

TCP Socket listening but does not send ACK+SYN

Posted on 2006-11-30
7
2,552 Views
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.
0
Comment
Question by:tmelo49
  • 4
  • 3
7 Comments
 
LVL 4

Accepted Solution

by:
Trilotech earned 250 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.
0
 

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.
0
 
LVL 4

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.
0
Microsoft Certification Exam 74-409

Veeam® is happy to provide the Microsoft community with a study guide prepared by MVP and MCT, Orin Thomas. This guide will take you through each of the exam objectives, helping you to prepare for and pass the examination.

 

Author Comment

by:tmelo49
ID: 18047834
It is an IP that is accessible from the rest of the network.
0
 

Author Comment

by:tmelo49
ID: 18048488
I figured out the problem......incorrect hosts file entry for localhost .
0
 

Author Comment

by:tmelo49
ID: 18048511
Thanks Trilotech. You put me on the right path.
0
 
LVL 4

Expert Comment

by:Trilotech
ID: 18048524
No problem. Glad you got it!
0

Featured Post

PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Meet the world's only “Transparent Cloud™” from Superb Internet Corporation. Now, you can experience firsthand a cloud platform that consistently outperforms Amazon Web Services (AWS), IBM’s Softlayer, and Microsoft’s Azure when it comes to CPU and …
If you're not part of the solution, you're part of the problem.   Tips on how to secure IoT devices, even the dumbest ones, so they can't be used as part of a DDoS botnet.  Use PRTG Network Monitor as one of the building blocks, to detect unusual…
Internet Business Fax to Email Made Easy - With  eFax Corporate (http://www.enterprise.efax.com), you'll receive a dedicated online fax number, which is used the same way as a typical analog fax number. You'll receive secure faxes in your email, f…
Here's a very brief overview of the methods PRTG Network Monitor (https://www.paessler.com/prtg) offers for monitoring bandwidth, to help you decide which methods you´d like to investigate in more detail.  The methods are covered in more detail in o…

770 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question