From nobody Mon Sep 29 21:32:59 2025 X-Original-To: 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 4cbDvL150jz68sc5 for ; Mon, 29 Sep 2025 21:33:18 +0000 (UTC) (envelope-from pusateri@keehole.org) Received: from kem.keehole.org (kem.keehole.org [136.41.224.255]) (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 4cbDvJ56Kzz436H for ; Mon, 29 Sep 2025 21:33:16 +0000 (UTC) (envelope-from pusateri@keehole.org) Authentication-Results: mx1.freebsd.org; dkim=pass header.d=keehole.org header.s=202408 header.b=FPrkMGGh; dmarc=pass (policy=none) header.from=keehole.org; spf=pass (mx1.freebsd.org: domain of pusateri@keehole.org designates 136.41.224.255 as permitted sender) smtp.mailfrom=pusateri@keehole.org Received: from smtpclient.apple (unknown [136.41.224.198]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by kem.keehole.org (Postfix) with ESMTPSA id A110A74B91 for ; Mon, 29 Sep 2025 17:33:09 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=keehole.org; s=202408; t=1759181589; bh=zaWKuHj/2ET8IFEVjzRdFimbFooRR1ibiV9A6IHYVKo=; h=From:Subject:Date:To:From; b=FPrkMGGhwnl2y9mKYCIpPlWyz3URAG+utL+tbbN6RRmyHxKtNEbradk2L/Rp5QMdb XFlfDAe3D44ZMMut0zTYikL7W5ssYhbmpmSX/hz1hioghdIVCT/av6qBZRx1MCuYYk gznENTjGIVPZUZat0P7SYFNHQwPnba/i5JA4YSEJTZwUZUf4cfi0OI6hQgk/sjUQ95 iGf+Lvcvh8LUItaUtpLcwrNEWR1VdmdVTETEsKvhfzjgu2m1xCAJpXS2j8CSTN1pzD NrFnZTzCGBF78Ue9O2ae4U76IzjAH0tRQ7232xB3elvFzZRfZd/L2beS7NaGyLUoPn +1pHjTlV7Fsdg== From: Tom Pusateri Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable 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 (Mac OS X Mail 16.0 \(3826.700.81\)) Subject: IPv6 accept_rtadv for default route and prefix but force host portion of /64 address? Message-Id: Date: Mon, 29 Sep 2025 17:32:59 -0400 To: "net@freebsd.org" X-Mailer: Apple Mail (2.3826.700.81) X-Spamd-Bar: -- X-Spamd-Result: default: False [-2.80 / 15.00]; SUBJECT_ENDS_QUESTION(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-1.00)[-0.999]; DMARC_POLICY_ALLOW(-0.50)[keehole.org,none]; ONCE_RECEIVED(0.20)[]; R_SPF_ALLOW(-0.20)[+mx]; R_DKIM_ALLOW(-0.20)[keehole.org:s=202408]; MIME_GOOD(-0.10)[text/plain]; RCVD_TLS_ALL(0.00)[]; TO_DN_EQ_ADDR_ALL(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_TRACE(0.00)[keehole.org:+]; RCPT_COUNT_ONE(0.00)[1]; FROM_HAS_DN(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; PREVIOUSLY_DELIVERED(0.00)[net@freebsd.org]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_ONE(0.00)[1]; MLMMJ_DEST(0.00)[net@FreeBSD.org]; APPLE_MAILER_COMMON(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; MIME_TRACE(0.00)[0:+] X-Rspamd-Queue-Id: 4cbDvJ56Kzz436H Is there a way to change the configuration in /etc/rc.conf to get the = prefix from the router advertisement but fix the host portion to = something like ::123 so that I can change network cards in the server = and never have to worry about the IPv6 address changing? I have a DMZ interface on a FreeBSD router with a prefix delegation from = my provider I assign to a downstream interface. I have another FreeBSD = server on the DMZ network and would like it to have a fixed address = allocated out of the assigned prefix from the router. The router (also FreeBSD) is running rtadvd providing SLAAC and router = advertisements. The /etc/rc.conf for the DMZ server currently looks like this: ifconfig_igb0_ipv6=3D"inet6 2605:1:2:3::123/64 accept_rtadv=E2=80=9D This works fine and manually assigns the address out of the assigned = prefix range as configured on the router. It also assigns a second IPv6 address via SLAAC that I don=E2=80=99t = use. ifconfig output looks like this: igb0: flags=3D1008843 = metric 0 mtu 1500 = options=3D4e527bb ether ac:1f:6b:1a:04:c0 inet 1.2.3.123 netmask 0xfffffff8 broadcast 1.2.3.127 inet6 fe80::ae1f:6bff:fe1a:4c0%igb0 prefixlen 64 scopeid 0x1 inet6 2605:1:2:3::123 prefixlen 64 inet6 2605:1:2:3:ae1f:6bff:fe1a:4c0 prefixlen 64 autoconf pltime = 604800 vltime 2592000 media: Ethernet autoselect (1000baseT ) status: active nd6 options=3D23 I get the correct upstream next hop for a default route: % netstat -nra6 Routing tables Internet6: Destination Gateway Flags = Netif Expire ::/96 link#3 URS = lo0 default fe80::207:43ff:fe31:7078%igb0 UG = igb0 The problem with this is that the IPv6 prefix is configured on the = router and configured on the server. Thanks, Tom