Ethereal-users: Re: [Ethereal-users] Displaying data on screen is slow

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From: Guy Harris <gharris@xxxxxxxxx>
Date: Mon, 7 Jan 2002 02:19:24 -0800
On Mon, Jan 07, 2002 at 09:54:31AM -0000, Richard Urwin wrote:
> I don't know what transport names are (anyone want to enlighten me?)

Names corresponding to transport-layer protocol port numbers, e.g.:

	% egrep domain /etc/services
	domain           53/tcp    #Domain Name Server
	domain           53/udp    #Domain Name Server

"domain" corresponding to port 53 for the TCP and UDP transport
protocols.

> but they dont seem to be a problem on my system.

Link-layer addresses are resolved by Ethereal by looking in a file, not
by calling a routine such as "gethostbyaddr()" that sends out packets
and waits for replies - replies that may not ever arrive, so that the
wait eventually has to time out.

Transport-layer port names are usually resolved by looking in a file as
well, although the routine Ethereal calls, "getservbyport()", could
conceivably use NIS, at least on UNIX systems - but you're more likely
to have some arbitrary DNS server not respond to a query than to have
your local NIS server respond to a query, and even more likely to have
nobody respond to a NetBIOS Name Service query (that's what Windows'
"gethostbyaddr()" will send out if the DNS request doesn't return a host
name).