Ethereal-dev: RE: [Ethereal-dev] tethereal filter on specific protocol

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 This list is no longer active.

From: "Patnaik, Anjela" <APatnaik@xxxxxxxxx>
Date: Tue, 3 Sep 2002 16:58:33 -0400
Actually, I meant a Read Capture filter.
Basically, if I have 20+ GIOP plugins built,
how do I capture only packets that dissect
a given GIOP plugin ??

Thanks,
ap

-----Original Message-----
From: Guy Harris [mailto:gharris@xxxxxxxxx]
Sent: Tuesday, September 03, 2002 2:38 PM
To: Patnaik, Anjela
Cc: 'ethereal-dev@xxxxxxxxxxxx'
Subject: Re: [Ethereal-dev] tethereal filter on specific protocol


On Tue, Sep 03, 2002 at 10:26:18AM -0400, Patnaik, Anjela wrote:
> How about a way in tethereal to choose a given
> protocol?

What do you mean by "choose"?

Do you mean "a way to have a capture only save packets for a given
protocol?

If so, then:

> I think my syntax may be wrong. I have
> several GIOP plugins that I have built, but
> want to only display a given kind, named plugin1.
> 
> Do a specify "proto giop-plugin1"?

No.

That's a capture filter, and the syntax of capture filters is described
by the tcpdump man page, which says, of "proto", in the current CVS
version of tcpdump:

	      proto  qualifiers  restrict the match to a particu-
		     lar protocol.  Possible protos  are:  ether,
		     fddi,  tr, wlan, ip, ip6, arp, rarp, decnet,
		     tcp and udp.  E.g., `ether  src  foo',  `arp
		     net  128.3',  `tcp port 21'.  If there is no
		     proto qualifier,  all  protocols  consistent
		     with  the type are assumed.  E.g., `src foo'
		     means `(ip or arp or rarp) src foo'  (except
		     the  latter  is not legal syntax), `net bar'
		     means `(ip or arp	or  rarp)  net	bar'  and
		     `port 53' means `(tcp or udp) port 53'.

	      [`fddi'  is  actually  an  alias	for  `ether'; the
	      parser treats them  identically  as  meaning  ``the
	      data  link  level  used  on  the	specified network
	      interface.''  FDDI  headers  contain  Ethernet-like
	      source and destination addresses, and often contain
	      Ethernet-like packet types, so you  can  filter  on
	      these FDDI fields just as with the analogous Ether-
	      net  fields.   FDDI  headers  also  contain   other
	      fields,  but  you  cannot name them explicitly in a
	      filter expression.

	      Similarly, `tr' and `wlan' are aliases for `ether';
	      the  previous  paragraph's  statements  about  FDDI
	      headers also apply to Token Ring and  802.11  wire-
	      less LAN headers.  For 802.11 headers, the destina-
	      tion address is the DA field and the source address
	      is  the  SA  field;  the	BSSID,	RA, and TA fields
	      aren't tested.]

The only valid values for "proto" are some that are hardwired in (and
that don't include arbitrary GIOP protocols), TCP or UDP port numbers
(which would require you to know the port number or numbers on which the
GIOP protocol in question would run; Ethereal and Tethereal cannot
magically determine that), or port names as found in the "/etc/services"
file or other service name databases (which would only include
well-known and reserved port numbers).

You would have to use a "read filter" to select your protocol, unless
you know the TCP port number your protocol will be using.  A "read
filter" has the syntax of a display filter, so it'd just be the protocol
name you assigned to the protocol your plugin dissects.

See the Tethereal man page for information on how to specify a read
filter.

(And if you're sending mail to ethereal-dev, don't send it directly to
me as well; I'm on ethereal-dev, so sending it directly to me as well
means I get two copies of the mail, which is one more copy than I want.)