Hi Bui Tuan,

as Peter already explained, debugging should be key here. Also additional information might help, e.g., are you really using the same user (as Rivalino already asked)? Are your login in to a graphical environment or just to the shell? Do you get any error messages in your code? All this might help to solve your question.

Best,

  Marc

You can try running your application with "strace".   That will give you detailed file, device, and system call level details (to stdout) as it runs.

Dear all,

Thanks to the comments and lessons.

So sorry for my lack of knowledge.

I've just started my work for a few months but there are too many skills to learn; that makes me too confused.

Anyway, I am reading the comments and checking more.

Hope I can find something

When on through ssh type the following commands:

id

echo $PATH

Then do the same thing when directly logged in.

Are you the same userid (uid) in both cases?  Is one of them root?

If they both are the same, then look at the $PATH, is it the same in both cases?

If that all matches then you have to look further into whats different,  you could look at your environments

type:

env

Some years ago, I encountered a problem like this.  In my case, it was a program with a graphical user interface that would not run from a normal terminal command line, but would run correctly if you used ssh to login to that machine.  It's been a while, but I think the problem was that my DISPLAY environment variable was being set incorrectly, probably in my .bashrc file.  

You could compare the value of your DISPLAY variable to that of your lab mates by having each of you enter:

  echo $DISPLAY

You can also do the same thing by yourself: login from the console and enter that; then ssh from a different machine and enter that; then compare the results.

Here is one possibility, based on your problem description: do you have any traffic on this PC when you are not logged into it via ssh?

When you log in via ssh, everything you type and everything returned by the program means network traffic. So if the program is monitoring network traffic, it will see continuous activity.

However, when you log on to this computer locally, there may be no or little network activity (depending on what kind of connectivity this computer has.) That may explain why your program is not seeing much data.

Thanks to all of your suggestion and comment.

This is really the first time I work with multi thread, tcp/ip, linux and the work is advanced to me. I am confused of many things.

you comments are really experiences and lessons. 

carefully read the source-library several times helps me solved the problem (as I edited in the beginning of my post)