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Wireshark-users: Re: [Wireshark-users] Analyzing a "broken" FTP session

From: "Chivian, John" <jchivian@xxxxxxxxxxxxxx>
Date: Fri, 21 Aug 2009 10:28:31 -0700
Thanks Martin.   The clipped packet captures are attached.   

Client info:
$ # the command line FTP client was used
$ uname -a
Linux hostname-masked 2.6.9-55.0.12.ELsmp #1 SMP Fri Nov 2 12:38:56 EDT 2007 x86_64 x86_64 x86_64 GNU/Linux
$ cat /etc/redhat-release
CentOS release 4.7 (Final)

Server info:
$ # a commercial FTP server daemon
$ uname -a
Linux hostname-masked 2.6.9-89.0.7.ELsmp #1 SMP Wed Aug 5 14:12:18 EDT 2009 i686 athlon i386 GNU/Linux
$ cat /etc/redhat-release
Red Hat Enterprise Linux ES release 4 (Nahant Update 8)

Network information:
The systems are both operating at 100 Mb/s.
They are both in the same physical location.
Client <-> Switch <-> Router <-> Switch <-> Server
The problem is generally seen with FTP sessions involving hundreds of small files.


I understand that the issue may be network as opposed to server related, and I understand that the packet captures may not contain enough information to make a definitive judgment.

Thanks all for your help!

JC


   

From: wireshark-users-bounces@xxxxxxxxxxxxx [mailto:wireshark-users-bounces@xxxxxxxxxxxxx] On Behalf Of Martin Visser
Sent: Friday, August 21, 2009 2:49 AM
To: Community support list for Wireshark
Subject: Re: [Wireshark-users] Analyzing a "broken" FTP session

Posting snippets of packet captures with reasonable problem reports are generally welcome. A lot of us here enjoy the challenge of trying interpret a stream of bytes with the hope of actually diagnosing the higher level issue that may be causing the problem. 

That said, some of us do this work for a living and get paid quite a bit of money to do it, so doing it for free is only viable if it doesn't take a lot of time. Any time I respond to such requests is out of a spirit of mentoring the community and also hopefully giving myself a little confidence that I actually sometimes know what I am talking about :-)

So please post, but also understand the context of the community.

Regards, Martin

MartinVisser99@xxxxxxxxx

On Fri, Aug 21, 2009 at 12:36 PM, Chivian, John <jchivian@xxxxxxxxxxxxxx> wrote:
Group:

  I'm not sure if this is the correct forum for this but I am hoping to get some help identifying a problem that sometimes occurs between an FTP client and server.   (If this isn't the right forum can someone point me in the right direction?)

  I have PCAP files made on both systems using tcpdump that have captured a recent failure, but I do not have enough expertise in packet analysis or the guts of the FTP protocol to read them and draw a definitive conclusion regarding why the connection "broke".

  If someone can help I am happy to provide more information regarding the systems themselves, the network topology between them, and the trimmed PCAP files for analysis.

  Thanks in advance, JC

---
 
John (JC) Chivian
Staff Software Engineer
Staff Unix/Linux Administrator
Corporate Information Systems
Photronics, Inc.
 
mailto:jchivian@xxxxxxxxxxxxxx
http://www.photronics.com
 
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