From owner-freebsd-hackers Sun Sep 28 02:26:24 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id CAA21807 for hackers-outgoing; Sun, 28 Sep 1997 02:26:24 -0700 (PDT) Received: from verdi.nethelp.no (verdi.nethelp.no [195.1.171.130]) by hub.freebsd.org (8.8.7/8.8.7) with SMTP id CAA21791 for ; Sun, 28 Sep 1997 02:26:18 -0700 (PDT) From: sthaug@nethelp.no Received: (qmail 22416 invoked by uid 1001); 28 Sep 1997 09:26:13 +0000 (GMT) To: tlambert@primenet.com Cc: freebsd-hackers@freefall.FreeBSD.org Subject: Re: r-cmds and DNS and /etc/host.conf In-Reply-To: Your message of "Sat, 27 Sep 1997 21:29:41 +0000 (GMT)" References: <199709272129.OAA11592@usr08.primenet.com> X-Mailer: Mew version 1.05+ on Emacs 19.28.2 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Date: Sun, 28 Sep 1997 11:26:12 +0200 Message-ID: <22414.875438772@verdi.nethelp.no> Sender: owner-freebsd-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk > Technically 127.1 and 127.0.0.1 are synonymous; one would think the > code should know this... Technically, 127.0.0.1 for the loopback address is a Berkeley-ism, but it is now cast in stone, since RFC1700 defines (g) {127, } Internal host loopback address. Should never appear outside a host. As far as I can see, this change occurred in two steps: - RFC 820 (January 1983 "Assigned Numbers") doesn't mention 127.*.*.*. - RFC 870 (October 1983 "Assigned Numbers") has 127.*.*.* as "reserved". - RFC 990 (November 1986 "Assigned Numbers") has 127.*.*.* explicitly as loopback. 127.1 as an alternative way of writing 127.0.0.1 is also a Berkeley-ism, as far as I know. The name server (BIND) knows nothing about it, and the inet_pton() routine (part of POSIX 1003.1g work in progress) does not recognize this format, even if inet_addr() and inet_ntoa() does. It is *not* a particularly good idea to depend on 127.1 being interpreted as 127.0.0.1. Steinar Haug, Nethelp consulting, sthaug@nethelp.no