Suggest a way to hang a HPUX 11.11 server's TCP/IP stack?

[Hangman]

That's the only way I can describe what I'm trying to do.

I need to simulate a problem so that I can get a fix for a piece of software we use.

This is a client-server software that connects via TCP to remote clients. If any one of the clients is unavailable (read: not DOWN, but "unavailable" meaning it responds to pings but not to new TCP/IP connections), then this piece of software will wait indefinitely for that malfunctioning client.

I am wondering if anyone can suggest some tools to be able to diagnose this problem, or even better yet to cause it to happen at will!

I promise I won't do it maliciously!

[Peter Godron]

Hi,
can you not block the port the program is trying to connect to ? Effect would be that ping works, but TCP connect would not.

[Coolmar]

I agree, you can simply block the port that your application is trying to access. Here is some software that will allow you to block the port:

http://h20293.www2.hp.com/portal/swdepot/displayProductInfo.do?productNumber=B9901AA

[Hangman]

No, sorry. I knew I'd screw up that post if I didn't proofread it!

Blocking the port is not what I need. blocking the port is accomodated by the software just as if the box is down. That's not a problem, it's only when there is some kind of hanging condition...

[Peter Godron]

Hi,
your hanging condition would be simulated by the program sending data to the TCP connection, but never hearing anything back ?

If this is the case, just have a program read the port in a loop, but never write to it. i.e. the port becomes a 'black hole'.

[Hangman]

No, sorry. I didn't proofread my post.

blocking a TCP post will NOT help me. The software handles unavailable ports and machines, it is only when the machine is in some kind of hung state that is a problem.

[Hangman]

Peter,

I believe that is the case.
I just don't quite know how to replicate this problem.

I've had the problem on both Windows servers and HPUX servers where that server hangs, I was thinking it may be easier to manipulate a UNIX box instead of trying to go down the Windows path. (Of course it might be easier to hang a Windows box???)

You see my dilemma!

[Sandman! · Accepted solution]

Try setting a timeout for the socket connection so that after the server has sent a few packets out and has not received any ACKs from the client, the server decides to shutdown that specific socket connection.

~hope it helps

[Sandman!]

By the way can you specify what is the status of those socket connections on the server side i.e. FIN_WAIT_2 or FIN_WAIT_1 etc.. Similarly what about the status of those socket connections on the client side?