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

Note: This archive is from the project's previous web site, ethereal.com. This list is no longer active.

Date Index Thread Index Other Months All Mailing Lists
Date Prev Date Next Thread Prev Thread Next
From: Matthijs Melchior <mmelchior@xxxxxxxxx>
Date: Sun, 15 Feb 2004 17:27:36 +0100
Alexander,

Alexander W. Janssen wrote:


Hello,

my company has a lot of protocols where the full definition is available in
ASN.1. The messages are BER encoded. I found out that ethereal has some sort
of BER decoder and i wonder how to use or extend it to support our own
protocols.

So, my question is: Is there a ASN.1 interpreter (subsequent to the BER
decoder) included? If not, how do i bash my own ASN.1 definitions into that
framework? I was thinking about pushing the definitions through a asn.1
compiler and hack the output into some sort of framework which fits into that
asn.1 stuff in Ethereal.

Are there more specific pointers about that subject?

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.

Ethereal will than display the ASN.1 messages with values annotated with
their types and names.

I use the Debian package to provide me with snacc[1.3bbn-5], use google
to find other instances of snacc.

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

--
Regards,
----------------------------------------------------------------  -o)
Matthijs Melchior                                       Maarssen  /\\
mmelchior@xxxxxxxxx                                  Netherlands _\_v
---------------------------------------------------------------- ----