From owner-freebsd-stable  Sun Sep 23 15: 5:36 2001
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To: "Juha Saarinen" <juha@saarinen.org>
Cc: freebsd-stable@FreeBSD.ORG
Subject: Re: loopback not working for anything other than 127.0.0.1 
In-reply-to: Your message of "Mon, 24 Sep 2001 09:15:38 +1200."
             <003401c14474$e4d53e40$0a01a8c0@den2> 
Date: Sun, 23 Sep 2001 15:04:58 -0700
From: "Kevin Oberman" <oberman@es.net>
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> From: "Juha Saarinen" <juha@saarinen.org>
> Date: Mon, 24 Sep 2001 09:15:38 +1200
> 
> :: I don't think any RFC actually calls for this, but 1122 is probably
> :: the relevant reference. From 3.2.1.3:
> :: (g)  { 127, <any> }
> :: 
> ::      Internal host loopback address.  Addresses of this form
> ::      MUST NOT appear outside a host.
> 
> RFC 990 seems to cover it though:
> 
>          The class A network number 127 is assigned the "loopback"
>          function, that is, a datagram sent by a higher level protocol
>          to a network 127 address should loop back inside the host.  No
>          datagram "sent" to a network 127 address should ever appear on
>          any network anywhere.

Except that 990 (and many similar RFCs) are an enumeration of assigned
numbers, not a specification of operation. I read it very similarly
to 1122. It assigned 127.0.0.0/8 as the loopback net and forbids any
packet addressed to that /8 from leaving the host. It must be sent out
to the lo interface.

It says nothing about how the host should respond to receiving the
packet.

R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman@es.net			Phone: +1 510 486-8634

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