Re: New official link-layer type request

[Guy Harris <gharris () sonic net>]

On May 18, 2019, at 3:54 PM, Michael Richardson <mcr () sandelman ca> wrote:

> Guy Harris <gharris () sonic net> wrote:
> > If we *do* use pcapng, that would mean that:
>
> > 1) Wireshark wouldn't be able to read the lawful intercept information
> > in the files until support for new block types and options are added to
> > it;
>
> Is wireshark modular in how it handles pcapng blocks?

Somewhat, although it could probably use more work.

> > 2) tcpdump wouldn't be able to read the lawful intercept information in
> > the files until we add full pcapng support (with new APIs) to libpcap,
> > including support for the new block types and options, and add support
> > for the new APIs, and for the new block types and options, to tcpdump;
>
> I hope to solve this in 2019/2020.

Definitely.  The sooner, the better; that would allow capturing on Linux, for example, to supply direction information 
for *all* link-layer header types (or, at least, for all link-layer header types provided by regular Linux interfaces), 
as well as providing IDBs for all interfaces when capturing on the "any" device, so that you could see what interface 
each packet came in on, even if you're reading the file on a machine other than the one on which the capture was done.

> > To be fair, those programs would *also* have to be modified to handle
> > LINKTYPE_ELEE - and programs that can read pcapng would at least be
> > able to read the intercepted packets without change, assuming they just
> > ignore unknown block and option types (which they should do!).
>
> :-)
> My thought is that the regular packets would be in regular blocks, and the
> extra info would be in the extended blocks.  So without extensions, one can
> read the packets and do stuff with them, but not know, for instanse, which
> link they came from, or maybe (I have no idea if this is real meta-info)
> which warant was used to obtain the data.

Exactly.
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