From owner-freebsd-hackers@freebsd.org Mon Apr 26 15:12:42 2021 Return-Path: Delivered-To: freebsd-hackers@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 7233D5E3370 for ; Mon, 26 Apr 2021 15:12:42 +0000 (UTC) (envelope-from phk@critter.freebsd.dk) Received: from phk.freebsd.dk (phk.freebsd.dk [130.225.244.222]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4FTT0T4HRrz3kMb for ; Mon, 26 Apr 2021 15:12:41 +0000 (UTC) (envelope-from phk@critter.freebsd.dk) Received: from critter.freebsd.dk (v-critter.freebsd.dk [192.168.55.3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by phk.freebsd.dk (Postfix) with ESMTPS id 8B3A18928F; Mon, 26 Apr 2021 15:12:39 +0000 (UTC) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.16.1/8.16.1) with ESMTPS id 13QFCc7p076800 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Mon, 26 Apr 2021 15:12:39 GMT (envelope-from phk@critter.freebsd.dk) Received: (from phk@localhost) by critter.freebsd.dk (8.16.1/8.16.1/Submit) id 13QFCcHL076799; Mon, 26 Apr 2021 15:12:38 GMT (envelope-from phk) To: "Rodney W. Grimes" cc: freebsd-hackers@freebsd.org Subject: Re: Are there any RFCs for address selection for IPv4 In-reply-to: <202104261456.13QEuXEa098219@gndrsh.dnsmgr.net> From: "Poul-Henning Kamp" References: <202104261456.13QEuXEa098219@gndrsh.dnsmgr.net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <76797.1619449958.1@critter.freebsd.dk> Date: Mon, 26 Apr 2021 15:12:38 +0000 Message-ID: <76798.1619449958@critter.freebsd.dk> X-Rspamd-Queue-Id: 4FTT0T4HRrz3kMb X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=pass (mx1.freebsd.org: domain of phk@critter.freebsd.dk designates 130.225.244.222 as permitted sender) smtp.mailfrom=phk@critter.freebsd.dk X-Spamd-Result: default: False [-2.99 / 15.00]; RCVD_TLS_ALL(0.00)[]; ARC_NA(0.00)[]; FREEFALL_USER(0.00)[phk]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; R_SPF_ALLOW(-0.20)[+mx]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[freebsd.dk]; RBL_DBL_DONT_QUERY_IPS(0.00)[130.225.244.222:from]; SPAMHAUS_ZRD(0.00)[130.225.244.222:from:127.0.2.255]; RCVD_COUNT_THREE(0.00)[3]; TO_MATCH_ENVRCPT_SOME(0.00)[]; NEURAL_HAM_SHORT(-0.99)[-0.993]; RCPT_COUNT_TWO(0.00)[2]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; FORGED_SENDER(0.30)[phk@phk.freebsd.dk,phk@critter.freebsd.dk]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:1835, ipnet:130.225.0.0/16, country:EU]; FROM_NEQ_ENVFROM(0.00)[phk@phk.freebsd.dk,phk@critter.freebsd.dk]; MAILMAN_DEST(0.00)[freebsd-hackers] X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Technical discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 26 Apr 2021 15:12:42 -0000 -------- Rodney W. Grimes writes: > > It is OK to have a LL as next-hop. > > > > It is not OK to send a packet with dst=LL to any next-hop. > > No, that is explicity forbidden: > RFC 3927 at 2.7 paragraph 2: > > An IPv4 packet whose source and/or destination address is in the > 169.254/16 prefix MUST NOT be sent to any router for forwarding, and > any network device receiving such a packet MUST NOT forward it, > regardless of the TTL in the IPv4 header. Right the second criteria should be: It is not OK to send a packet with src=LL or dst=LL to any next-hop. But it /is/ OK to have a next-hop router on a LL, but it is no use, unless your host has another interface with a "real" IP on it. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.