From owner-freebsd-hackers@freebsd.org Sun Apr 25 12:12:41 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 BF6655FFA61 for ; Sun, 25 Apr 2021 12:12:41 +0000 (UTC) (envelope-from gljennjohn@gmail.com) Received: from mail-ej1-x62d.google.com (mail-ej1-x62d.google.com [IPv6:2a00:1450:4864:20::62d]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4FSn380Fgsz3JtM for ; Sun, 25 Apr 2021 12:12:35 +0000 (UTC) (envelope-from gljennjohn@gmail.com) Received: by mail-ej1-x62d.google.com with SMTP id r20so30522631ejo.11 for ; Sun, 25 Apr 2021 05:12:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:in-reply-to:references:reply-to :mime-version:content-transfer-encoding; bh=WlXcOl/8WXts0s6xt1SxJfwNNh5fq0Wce5anJaj1QCM=; b=GHC8a4Bw38jvtRZwPIpGI+btQ5MxPwjoCrB0nIo3aEJxVmguSMiqsEjx+xnkBYunpN ErbNt+jwLYA/+/HJ1ubXkvB/rLAjxLCqzzSbbxgjL2Bp/uXFqAjDR01Mcf8R/WqUlwoK soxYGo3ZDIz9FPljCZu1PrLCppwbVU61BTATaKkvSjcLlMqREP9MBiQ6ue6+LAMFnjQQ ICMAlbL/BoVMqZG1wNG/CWLLKEq+ulh/7s4EKaoX3yPSAN/lLkuDZR8qKAH2+BJWy24a pe0GiDxvYNJi1+8DuVTJ66/APjVrryIqPgQzcTM4iSsk3agwldnQrAEt3UtH6OCwvhJE bR7Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:reply-to:mime-version:content-transfer-encoding; bh=WlXcOl/8WXts0s6xt1SxJfwNNh5fq0Wce5anJaj1QCM=; b=Qgr2uRByvN2k3+DCkmHoocR5KTScfoqhYcXJdhwwSB/EXMeoPA1pYhiZ3sbH7xIIOw pLPlyTQxgq7eTZOigBd9sxPG73d0uMql/pgqpCdn4N6+iiB543tWApWclO2gffwPl+/R Hag6leVV5Tu2pDyGaHQ8GywvFVvvylueWmx/bmAZdDpW/1gV8tmei25kV9Ll/vBQo55q HdTJlvub/QOqUGqYvDDNMtyMZdpb5gvCcdZ7tNIYS4Gl3bzUgavyelK8zSVr2PtVTzV9 o8woNpEYjCvGJsQ21OQWjiR+MsbP7nowfmOKTDfKAE1kG1XLe5hx5R31ubzcANv/NMXf Q0LQ== X-Gm-Message-State: AOAM5315HE18JBy5dYKth39sbuhKL0xD0sqKaP+dr+wfLYZsl1+FZawj kxOeDyc7Exldr8MAtJKD1l0= X-Google-Smtp-Source: ABdhPJy/Ego8FtvqTG3WQ+B5ersFRp/5Cgx8r6WOfxStGJKQXHAlG03jDITQ3JsfJhEuz8q7G3XEvw== X-Received: by 2002:a17:907:75f6:: with SMTP id jz22mr4109163ejc.504.1619352754052; Sun, 25 Apr 2021 05:12:34 -0700 (PDT) Received: from ernst.home (pd9e23d76.dip0.t-ipconnect.de. [217.226.61.118]) by smtp.gmail.com with ESMTPSA id s11sm11884798edt.27.2021.04.25.05.12.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 25 Apr 2021 05:12:33 -0700 (PDT) Date: Sun, 25 Apr 2021 14:12:32 +0200 From: Gary Jennejohn To: Zhenlei Huang Cc: freebsd-hackers@freebsd.org Subject: Re: Are there any RFCs for address selection for IPv4 Message-ID: <20210425121232.0bdb424a@ernst.home> In-Reply-To: References: Reply-To: gljennjohn@gmail.com X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; amd64-portbld-freebsd14.0) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 4FSn380Fgsz3JtM X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20161025 header.b=GHC8a4Bw; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of gljennjohn@gmail.com designates 2a00:1450:4864:20::62d as permitted sender) smtp.mailfrom=gljennjohn@gmail.com X-Spamd-Result: default: False [-2.80 / 15.00]; HAS_REPLYTO(0.00)[gljennjohn@gmail.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; RBL_SENDERSCORE_FAIL(0.00)[2a00:1450:4864:20::62d:query timed out]; TO_DN_SOME(0.00)[]; FREEMAIL_FROM(0.00)[gmail.com]; R_SPF_ALLOW(-0.20)[+ip6:2a00:1450:4000::/36]; REPLYTO_ADDR_EQ_FROM(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; DKIM_TRACE(0.00)[gmail.com:+]; RCPT_COUNT_TWO(0.00)[2]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; FREEMAIL_TO(0.00)[gmail.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US]; RBL_DBL_DONT_QUERY_IPS(0.00)[2a00:1450:4864:20::62d:from]; DWL_DNSWL_NONE(0.00)[gmail.com:dkim]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-0.997]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20161025]; RECEIVED_SPAMHAUS_PBL(0.00)[217.226.61.118:received]; FROM_HAS_DN(0.00)[]; NEURAL_SPAM_SHORT(0.19)[0.192]; NEURAL_HAM_LONG(-1.00)[-1.000]; TAGGED_RCPT(0.00)[]; FREEMAIL_REPLYTO(0.00)[gmail.com]; PREVIOUSLY_DELIVERED(0.00)[freebsd-hackers@freebsd.org]; MIME_GOOD(-0.10)[text/plain]; SPAMHAUS_ZRD(0.00)[2a00:1450:4864:20::62d:from:127.0.2.255]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_IN_DNSWL_NONE(0.00)[2a00:1450:4864:20::62d:from]; RCVD_TLS_ALL(0.00)[]; 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: Sun, 25 Apr 2021 12:12:41 -0000 On Sun, 25 Apr 2021 18:20:37 +0800 Zhenlei Huang wrote: > Hello hackers, > > For IPv6 there's RFC 6724 to clarify the default address selection procedure, > both for source address selection and destination address selection. Are there > any RFCs like RFC 6724 that are for IPv4? > > I'm exploring RFC 3927, consider this situation, a host configured with link-local > address on NIC and global unicast alias address on loopback interface, and default route to > the link-local address of router (some ISPs do this). The current implementation kernel > will use the link-local address as the source address when initializing a connection to > remote host via the default route. It seems wrong, as link-local address are not > routable as per RFC 3927. > > So it is important if there's corresponding RFC clarify the source address selection > for IPv4. > > Thanks :) > I'm no expert on this, but the router must have a public, routable adress to the internet, otherwise it can't function as a router. This address is (usually) provided by the ISP. It's using its pubic address to route packets to the internet and very probably NAT to handle packets from and to the LAN. So, the internal LAN does not have to use routable addresses. -- Gary Jennejohn