Wireshark · Ethereal-dev: Re: [Ethereal-dev] how to decode BER encoded ASN.1 messages over TCP?

["Alexander W. Janssen" <alexander.janssen@xxxxxx>]

On Sun, Feb 15, 2004 at 05:27:36PM +0100, Matthijs Melchior wrote:
Hello Matthijs,

> The ethereal ASN.1 dissector uses a type-table to describe the ASN.1 types
> and values.  This type-table is generated by 'snacc', a free ASN.1 compiler
> suite, and in the configuration pane for the dissector you point it to such
> a .tt file and mention the name of the top-level PDU and the port where
> to expect these messages in a data stream.

Yes, i allready figured that out and used snacc to create the table-type. It
worked as expected. Good job! This is very handy for me :)

I just got one problem, sometimes it seems not to dissect the whole PDU; it
just shows "short frame" and the data seems to be crippled. I thought this was
due to fragments in the first place, but in none of the TCP packets the
more-fragments flag was set.

However, i think that the testdata i have is recorded with a too short
snaplength (tcpdump -s 94 is the default on that flavour of UNIX...). I will
first try and get complete test-data.

Btw, is there a possibilty to filter for certain aspects? Something like
asn1.somemsg.someoption.parameter == something?

> The source file for this dissector, plugins/asn1/packet-asn1.c in the
> ethereal tree, contains some more documentation.

Will have a look. Any plans for PER/XER et al. decoding? Not that any of our
protocols use it, but who knows, our R&D changed slowly to a java-monkey
department... *shiver*

Anyway, thank you for this very fine plugin! It's a blessing for people who
have to deal with all the ITU-T stuff.
 
Cheers, Alex.

-- 
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..O
OOO

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