Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!umiacs.UMD.EDU!steve
From: steve@umiacs.UMD.EDU
Newsgroups: comp.protocols.tcp-ip
Subject: Forwarding IP packets with source on net 0?
Message-ID: <8907051926.AA17106@fnord.umiacs.UMD.EDU>
Date: 5 Jul 89 19:26:05 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 26


   For various ugly reasons, the question of whether or not IP packets with
their source IP address on network 0 should be forwarded has come up here.
I don't see any direct prohibition in an admittedly quick perusal of the
Hosts Requirements draft or of the Gateway Requirements RFC.  Still, I can
see reasons for going either way, and I'm curious as to what others think.

   It seems to me that net 0 means 'this network', and that packets for this
network shouldn't leave it.  Consider what happens if a forward a packet
from net 0 to some other network.  When some other host gets that packet,
it's either got to respond using the net 0 source address as the destination
address (and thus violate RFC 1009, section 4.4), or it's got to use the
information in the packet to build a different reply to another IP address.
Maybe the latter either happens in real life, or should be allowed to
happen -- I just don't know.

   Opinions?  (Polite RTFMs are more than welcome.)

   (This came up in trying to boot a Sun-2 over the net.  I can provide more
details if people are interested; I don't think this will be a problem for
99.44% of all people Out There, but since it did come up...)

	-Steve

Spoken: Steve Miller    Domain: steve@mimsy.umd.edu    UUCP: uunet!mimsy!steve
Phone: +1-301-454-1808  USPS: UMIACS, Univ. of Maryland, College Park, MD 20742