From nobody Thu Jul 07 15:35:50 2022 X-Original-To: freebsd-net@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 7240C12AEB25 for ; Thu, 7 Jul 2022 15:36:01 +0000 (UTC) (envelope-from freebsd-rwg@gndrsh.dnsmgr.net) Received: from gndrsh.dnsmgr.net (br1.CN84in.dnsmgr.net [69.59.192.140]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4Lf0qh2l4jz3N4t for ; Thu, 7 Jul 2022 15:36:00 +0000 (UTC) (envelope-from freebsd-rwg@gndrsh.dnsmgr.net) Received: from gndrsh.dnsmgr.net (localhost [127.0.0.1]) by gndrsh.dnsmgr.net (8.13.3/8.13.3) with ESMTP id 267FZqOh021919; Thu, 7 Jul 2022 08:35:52 -0700 (PDT) (envelope-from freebsd-rwg@gndrsh.dnsmgr.net) Received: (from freebsd-rwg@localhost) by gndrsh.dnsmgr.net (8.13.3/8.13.3/Submit) id 267FZoL9021918; Thu, 7 Jul 2022 08:35:50 -0700 (PDT) (envelope-from freebsd-rwg) From: "Rodney W. Grimes" Message-Id: <202207071535.267FZoL9021918@gndrsh.dnsmgr.net> Subject: Re: experimental support for IPv4 unicast extensions In-Reply-To: <202207062206.266M6UVV033854@mail.karels.net> To: mike@karels.net Date: Thu, 7 Jul 2022 08:35:50 -0700 (PDT) CC: freebsd-net@FreeBSD.org X-Mailer: ELM [version 2.4ME+ PL121h (25)] List-Id: Networking and TCP/IP with FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-net List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-net@freebsd.org MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: 4Lf0qh2l4jz3N4t X-Spamd-Bar: / Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=none (mx1.freebsd.org: domain of freebsd-rwg@gndrsh.dnsmgr.net has no SPF policy when checking 69.59.192.140) smtp.mailfrom=freebsd-rwg@gndrsh.dnsmgr.net X-Spamd-Result: default: False [-0.09 / 15.00]; AUTH_NA(1.00)[]; NEURAL_HAM_SHORT(-0.99)[-0.989]; MIME_GOOD(-0.10)[text/plain]; R_SPF_NA(0.00)[no SPF record]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; MLMMJ_DEST(0.00)[freebsd-net]; ASN(0.00)[asn:13868, ipnet:69.59.192.0/19, country:US]; RCPT_COUNT_TWO(0.00)[2]; ARC_NA(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_TLS_LAST(0.00)[]; TO_DN_NONE(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; DMARC_NA(0.00)[dnsmgr.net]; MID_RHS_MATCH_FROM(0.00)[] X-ThisMailContainsUnwantedMimeParts: N > I have been corresponding with the authors of Internet-Drafts that relax > restrictions on parts of the IPv4 address space to allow normal unicast > use, and I have FreeBSD changes to allow experimentation with these > updates. This message summarizes my changes, and solicits input. > > The changes are all controlled by sysctl, and default to "off". > The parts of the address space in question and the relevant changes: > > 0/8 (network 0) [1]: Restrictions on network 0 are lifted if the sysctl > net.inet.ip.allow_zeronet is set to 1. This applies to packet forwarding > and ICMP echo. > > 224/4 (Experimental/"Class E") [2]: Restrictions on the Experimental > address class are lifted if the sysctl net.inet.ip.allow_experimental > is set to 1. This applies to packet forwarding and ICMP echo. > > 127/8 (loopback net) [3]: The size of the reservation for the loopback > network can be reduced from 127/8 to 127.0/16 using the sysctl > net.int.ip.loopback_mask. My current sysctl sets the mask, but that > is a little cumbersome; I should probably change the sysctl to allow > a mask length to be set. This change is limited to the kernel; the > IN_LOOPBACK macro uses the current mask in the kernel, but the default > mask at user level. Also, some user programs use IN_LOOPBACKNET along > with a Class A shift to crack this by hand. The kernel change affects > IP packet input and output as well as forwarding. > > The changes described above are all included in a single review for now, > although I would probably separate them before pushing them. (They > necessarily collide though.) The review is intended for comments only, > and is https://reviews.freebsd.org/D35741. I think it makes sense to > put these changes in -current in order to enable experimentation, but > I wanted to open the subject for discussion first. Mike, My first cut at this is in review: https://reviews.freebsd.org/D19316 Regards, Rod > > Changes are also being made in Linux, although I don't know their state. > > Note that there is a related proposal and change to allow use of the > lowest host on a network/subnet [4]. This change was essentially a bug > fix for FreeBSD, and is already in -current and 13.1-RELEASE. > > Mike > > [1] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-0/01/ > > [2] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-240/ > > [3] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-127/ > > [4] https://datatracker.ietf.org/doc/draft-schoen-intarea-unicast-lowest-address/ > > > -- Rod Grimes rgrimes@freebsd.org