Wireshark-users: Re: [Wireshark-users] running multiple instances
From: Nicole Powell <mznikkip@xxxxxxxxxxx>
Date: Tue, 10 Nov 2009 15:17:40 -0500
Yes I am performing the two commands from Python on the same pcap file (which gives an application error). But if I run the two commands, by themselves, from the command line:

tshark -r airodump.cap-01.cap -o column.format:"Info","%i" > output.txt
tshark -r airodump.cap-01.cap -V

Tshark does not give an application error. By the way, I tried running the commands from the command line with a pcap file as well and there's still no application error. So there shouldn't be any differences between the formats or the packets in the file if Tshark can handle them from the command line. Basically the only time the application error occurs is when I use a pcap file, running the commands from Python. I don't understand why it would run from the command line and not the Python program.

> Perhaps the Python interpreter is taking enough
> memory that you run out of swap/paging space, and thus cause attempts
> by TShark to allocate memory to fail?

I tried using a kill() command within the Python program and I get 'This process does not exist' which tells me that the command should be executing and then releasing that memory.

 





> From: guy@xxxxxxxxxxxx
> To: wireshark-users@xxxxxxxxxxxxx
> Date: Tue, 10 Nov 2009 10:19:35 -0800
> Subject: Re: [Wireshark-users] running multiple instances
>
>
> On Nov 10, 2009, at 9:33 AM, Nicole Powell wrote:
>
> > Could it also relate to cap vs. pcap file? I tried 145KB .cap file
> > and it ran fine but a 130KB .pcap file stalls tshark as well.
>
> What is a ".cap file"? There are at least two Windows packets I know
> of (Windows Sniffer and Microsoft Network Monitor) that use ".cap" as
> a suffix, and their file formats are different. Furthermore, there
> are probably at least some libpcap-format files that have ".cap" as
> the suffix.
>
> In any case, the chances that it's an issue with the file format are
> extremely slim; it's probably a problem with the packets in the file.
>
> Also, "stalls" and "gives an application error and shuts down" are
> different problems.
>
> > In addition, these commands are done using Python and that's when
> > the errors occurs. If I perform the commands from the command
> > prompt, it runs fine.
>
> (Perform them from the command prompt with the same file?)
>
> If you run them from Python, the Python interpreter and at least one
> instance of TShark are running at the same time. If you ran Python
> from the command line, the command-line shell, the Python interpreter,
> and at least one instance of TShark are running at the same time.
>
> If you run them from the command line, the command-line shell and at
> least one instance of TShark are running at the same time, but you're
> not running Python. Perhaps the Python interpreter is taking enough
> memory that you run out of swap/paging space, and thus cause attempts
> by TShark to allocate memory to fail?
>
> (This assumes the application error is a failure to allocate memory.)
>
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