Re: [Beepcore-java-users] BEEPcore broken w.r.t. TCP

[Harsh D. <hda...@io...>]

Forgive me for my ignorance but I don't understand how an application can
keep TCP stack from sending CLOSE? Can you describe a simple scenario that
I can simulate to reproduce this bug (not necessarily with beepcore-java).

Harsh
Mario Jeckle said:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Working these days on a research prototype with the lasted
> implementation of BEEP available from www.beepcore.org we discovered a
> serious flaw.
>
> Obviously the library does not issue TCP's CLOSE command after having
> received the CLOSING primitive which is received as a result of an TCP
> packet flagged with FIN. Actually, the ACK flagged message is sent back
> to the client by the server, but the required FIN message is missing.
>
> As a result of this the TCP connection of the server side remains in
> status CLOSE_WAITING almost forever until the process is killed or the
> machine is rebooted.
>
> This can be reproduced under various Linux versions including the
> latest kernel (i.e., 2.6.3) and even machines running Windows.
> Fortunately, Windows (XP) limits the number of processed in state
> CLOSE_WAITING to 15 per process and cleans the open connections without
> user interaction automatically if an additional one reaches the
> mentioned state.
>
> Concerning Unix/Linux versions (the problem of remaining CLOSE_WAITING
> connections is also reported for HP UX) this behavior of BEEPcore might
> introduce the possibility of attacking the machine running BEEP since
> the server will run out of free sockets after a while.
>
> Could you please re-check this since it hinders us from using BEEP in
> practice.
>
> Also feedback on this issue and even potential mistakes from our side
> is highly appreciated.
>
> Best,
> Mario
>
> - --
> Prof. Mario Jeckle
> University of Applied Sciences Furtwangen
> Dept. Business Applications of Computer Science
>
> W3C Representative of DaimlerChrysler Research and Technology
> OMG Representative of DaimlerChrysler
>
> URL: http://www.jeckle.de
> MailTo:ma...@je...
> MailTo:je...@fh...
>
> My public key: http://www.jeckle.de/marioJeckle.pub
>
> [mail really from me _always_ has this signature and is signed
> digitally - -- mail without it is forged spam]
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.2.2-rc1-SuSE (GNU/Linux)
> Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org
>
> iD8DBQFAQYMQ46tt20EwGqwRAkY7AKC87JxDWLTOJZFIEPU/DYY0jjjGOwCff29G
> lW8fiQ8bYCRDcAEez7Sf0CQ=
> =l6YW
> -----END PGP SIGNATURE-----
>
>
> -------------------------------------------------------
> SF.Net is sponsored by: Speed Start Your Linux Apps Now.
> Build and deploy apps & Web services for Linux with
> a free DVD software kit from IBM. Click Now!
> http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click
> _______________________________________________
> Beepcore-java-users mailing list
> Bee...@li...
> https://lists.sourceforge.net/lists/listinfo/beepcore-java-users


-- 
Harsh Daharwal
IOS Networks Inc.
http://www.iosnetworks.com