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From: Jim Fleming <JimFleming@unety.net>
To: "'Darren Reed'" <avalon@coombs.anu.edu.au>,
        Jim Fleming
	 <JimFleming@unety.net>
Cc: "FreeBSD-hackers@freebsd.org" <FreeBSD-hackers@freebsd.org>
Subject: RE: IPv8 Tutorial #1: Minimal IPv8 hack
Date: Sun, 5 May 1996 00:33:59 -0500
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On Sunday, May 05, 1996 10:25 AM, Darren Reed[SMTP:avalon@coombs.anu.edu.au] wrote:
@ In some mail from Jim Fleming, sie said:
@ > 
@ > 
@ > IPv8 Tutorial #1: Minimal IPv8 Hack
@ > ---------------------------------------------------
@ > 
@ > A few people have asked for a minimal hack for FreeBSD
@ > to process IPv8 packets in case they arrive at your interface.
@ [...]
@ > < 	/* Detect and fix IPv8 packets */
@ > < 	if(ip->ip_v & 8){
@ > < 		if(ip->ip_v & 4){
@ [...]
@ > < 	/* The IPv8 packet is now IPv4 compatible */
@ > < 
@ > 
@ > This hack can be placed near line #184.
@ [...]
@ 
@ Will someone please tell me what IPv8 is ?
@ 
@ I do know that there is an IPv6...
@ 
@ btw, I'd do the above as
@ 
@ if (ip->ip_v == IPVERSION6) {
@ 	if (ip->ip_v == IPVERSION) {
@ ...
@ 

There is an IPv8 header file referenced at...
	http://comm.unety.net/US/IL/Naperville/Unir

There are macros to test the version and options bits...

You have to use "&" and not "==" to make sure you
are testing just one bit at a time. Only the high bit
of the IPv4 version field (ip->ip_v) is used for version.
--
Jim Fleming
UNETY Systems, Inc.
Naperville, IL

e-mail: JimFleming@unety.net