Subject: Re: interception proxies

From: Charles Lynn <[email-masked]>
Date: Wed, 12 Apr 2000 10:21:43 +0500 (EDT)

Dick,

> Quoted from RFC791, the IP specification, in the section on loose
> source routing, page 19 [emphasis added]:
> 
>    If the address in destination address field has been reached and
>    the pointer is not greater than the length, the next address in
>    the source route replaces the address in the destination address
>    field, and the recorded route address REPLACES THE SOURCE
>    ADDRESS just used, and pointer is increased by four. 

You have misread the specification.  That "source" is not (IP Header)
"Source Address" that you imply, but the "source" mentioned earlier in
the sentence, i.e., "address in the source route" (option).

The IP Header Source Address is not changed by the source routing options.
(Nor in the case of IPv6 style source routing.)

[If you think about it, the interpretation you emphasized above will
not result in a capability for bi-directional communication.]

Charlie

---

From: "J. Noel Chiappa" <[email-masked]>
Date: Wed, 12 Apr 2000 12:10:46 -0400

> From: "Dick St.Peters" <[email-masked]>

    > The authors of the standard had the vision to foresee ...
    > they designed a protocol flexible enough to encompass things they
    > could not foresee.

Pardon me if I emit a "balderdash".

There's this tendency to act like IPv4 was handed down on stone tablets by
Athena, the Goddess of Wisdom, herself - and I want to stamp it out. *I was
there*, and trust me, it wasn't a much (any?) different case of sausage
production than the average standard today. (Trivia question: what's the
connection between 32-bit IP addresses and the number of registers
available at interrupt time in Tenex?)

They had great foresight, huh? The foresight to see the need for more
address bits (funnily enough, IP2.5 *had* this, and they *ripped it out* -
great vision there), traffic flows, etc (I could go on but what's the
point).

Yes, IPv4 had some good ideas, ideas that have turned out well. It also has
some woeful deficiencies. (In some cases these are deficiencies that not
even Einstein could have forseen, so don't get me wrong, I'm not trying to
throw rocks about them.)

However, let's not mythologize anything, OK? It gets in the way of
objective analysis.

	Noel