Ethereal-users: Re: [Ethereal-users] Looking for a description of the ring buffer

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From: Guy Harris <guy@xxxxxxxxxx>
Date: Thu, 10 Jan 2002 17:32:52 -0800 (PST)
> I am guessing it means how many temporary 65535 packet files to use before
> it starts to overwrite packets (SWAG).

65535 is not a wired-in ring buffer parameter of any sense, so that's
not it.

The manual page says:

OPTIONS
     -a	 Specify a criterion that specifies when Tethereal is to
	 stop writing to a capture file.  The criterion	is of the
	 form test:value, where	test is	one of:


	 duration
	     Stop writing to a capture file after value	seconds
	     have elapsed.

	 filesize
	     Stop writing to a capture file after it reaches a
	     size of value kilobytes (where a kilobyte is 1000
	     bytes, not	1024 bytes).


     -b	 If a maximum capture file size	was specified, causes
	 Ethereal to run in "ring buffer" mode,	with the
	 specified number of files.  In	"ring buffer" mode,
	 Ethereal will write to	several	capture	files; the name
	 of the	first file, while the capture is in progress,
	 will be the name specified by the -w flag, and
	 subsequent files with have .n appended, with n	counting
	 up.

	 When the first	capture	file fills up, Ethereal	will
	 switch	to writing to the next file, until it fills up
	 the last file,	at which point it'll discard the data in
	 the first file	and start writing to that file.	 When
	 that file fills up, Ethereal will discard the data in
	 the next file and start writing to it,	and so on.

	 When the capture completes, the files will be renamed to
	 have names based on the number	of the file and	on the
	 date and time at which	packets	most recently started
	 being written to the file.