From nobody Thu Nov 04 14:28:02 2021 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 B739918293DA for ; Thu, 4 Nov 2021 14:28:11 +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 4HlQwW3Pjhz3qfx for ; Thu, 4 Nov 2021 14:28:11 +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 1A4ES2EV029644; Thu, 4 Nov 2021 07:28:02 -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 1A4ES2VL029643; Thu, 4 Nov 2021 07:28:02 -0700 (PDT) (envelope-from freebsd-rwg) From: "Rodney W. Grimes" Message-Id: <202111041428.1A4ES2VL029643@gndrsh.dnsmgr.net> Subject: Re: netmask for loopback interfaces In-Reply-To: <3244c917-d08a-c72b-5b5a-f74233cf47f5@shurik.kiev.ua> To: Oleksandr Kryvulia Date: Thu, 4 Nov 2021 07:28:02 -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: 4HlQwW3Pjhz3qfx X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; none X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[] X-ThisMailContainsUnwantedMimeParts: N > 04.11.21 01:01, Mike Karels ?????: > > I have a pending change to stop using class A/B/C netmasks when setting > > an interface address without an explicit mask, and instead to use a default > > mask (24 bits). A question has arisen as to what the default mask should > > be for loopback interfaces. The standard 127.0.0.1 is added with an 8 bit > > mask currently, but additions without a mask would default to 24 bits. > > There is no warning for missing masks for loopback in the current code. > > I'm not convinced that the mask has any meaning here; only a host route > > to the assigned address is created. Does anyone know of any meaning or > > use of the mask on a loopback address? > > > > Thanks, > > Mike > > > > /8 mask on loopback prevetnts using of 127.x.x.x network anywhere > outside of the localhost. This described in RFC 5735 [1] and 1122 [2] > > [1] https://datatracker.ietf.org/doc/html/rfc5735 > [2] https://datatracker.ietf.org/doc/html/rfc1122 Saddly that no longer works correctly since there is no longer a 127/8 route in the table. Which, IMHO, is a mistake. -- Rod Grimes rgrimes@freebsd.org