Ethereal-dev: Re: [Ethereal-dev] requested doc section, features, & question

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From: Guy Harris <gharris@xxxxxxxxx>
Date: Mon, 01 Aug 2005 22:39:25 -0700
Ken Kriesel wrote:
I would find it useful for there to be a specifications section in the ethereal
documentation, describing current limits of the program such as:

Number of bits of precision in byte counters for conversations, other statistics.
Maximum table size for endpoint addresses, conversations, etc.
Recommendations of minimum hardware versus speed of network to be
captured.

Also, does ethereal support error packet reporting & capture?

Ethereal could support error packet reporting from applications that support error packet capture, if we added a mechanism to Wiretap to provide that information from, for example, various flavors of Sniffers.

Ethereal could support error packet capture if the underlying drivers on the OS supplied them to libpcap/WinPcap and thus to Ethereal. Those drivers aren't under our control, so we can't make that happen. It would also at least help if the packet capture mechanism support getting information such as error flags (runt, CRC error, too long, etc.) from the driver, and supplying that information to code such as libpcap running on top of it. Getting that information to Ethereal would involve API changes to let libpcap provide that information to its callers, and a change to the libpcap file format (such as the pcap-NG format:

	http://www.winpcap.org/ntar/draft/PCAP-DumpFileFormat.html

) to store that information.

(Or, to put it another way, unlike the sorts of commercial packet analyzers to which Windows users might be familiar, Ethereal's not a "complete package", whose developers completely control the capture file format and the code path for capturing all the way down to the drivers; it's an application that runs atop existing packet capture mechanisms and uses an existing capture format, although some of us who are Ethereal developers are also in a position to at least *influence* the other components, although we're not in a position to *control* them.)