Date: Sun, 2 Apr 2000 03:49:53 +0400 (MSD) From: "Aleksandr A.Babaylov" <babolo@links.ru> To: ericp@troikanetworks.com (Eric Peterson) Cc: dot@dotat.at, nik@FreeBSD.ORG, hackers@FreeBSD.ORG Subject: Re: No route for 127/8 to lo0 (?) - another use for loopback subn et? Message-ID: <200004012349.DAA07016@aaz.links.ru> In-Reply-To: <C7CA595F9B9FD311A40D009027DC4A856E7E47@host03.troikanetworks.com> from "Eric Peterson" at "Mar 31, 0 09:08:39 am"
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Eric Peterson writes: [Charset iso-8859-1 unsupported, filtering to ASCII...] > Tony Finch [mailto:dot@dotat.at] wrote: > > Nik Clayton <nik@freebsd.org> wrote: > >> > >> I thought that 127/8 was the "local net", and that > >> packets sent to any of those addresses would go via > >> the loopback interface. That seems to be how Linux > >> and Windows 98 do things (the only systems I can > >> check this on at the moment). Assuming that's the > >> case, why does FreeBSD only add a a host route to > >> 127.0.0.1, and not a network route for 127/8? > > > > I did some further investigation to see how old this > > oddity is and it seems to be the way BSD has always > > handled the loopback interface. There's an explicit > > exclusion in the interface initialization code in in.c > > that gives loopback interfaces a host route instead of > > the network route that a normal interface gets and it's > > been that way for 15 years. > > I always thought it was a great waste of network address > space to devote an entire class A network to a single > loopback address. An idea I got from a co-worker a while > ago was to allow the 127.* (or some smaller subnet of 127) > to be devoted to "intra-box addresses", for example: > > 1. A cluster of devices/slots within a chassis > 2. A parallel processing machine > 3. A multi-processor computer/device > > All of the above may have inter-processor communications > that do not need to leave the chassis. Analogous to how > the 192.168.* (RFC1918) addresses are used for intranets, > these addresses wouldn't be allowed to be seen by the outside > world (i.e. outside the "chassis"), but would permit internal > IP communication without having to waste (and configure) a > "real" IP net number. If these devices needed to get to the > outside world, they could use NAT (again, analogously to the > RFC1918 case). I use addresses from 127/8 net for p2p connections when security is useful. TCP/IP pakets with 127.X.X.X has only one hop to live and never be routed by BSD kernel. may be 0/8 net is similar - I don't remember. -- @BABOLO http://links.ru/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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