From owner-freebsd-questions@freebsd.org Thu Jul 8 02:44:00 2021 Return-Path: Delivered-To: freebsd-questions@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 4C03066106B for ; Thu, 8 Jul 2021 02:44:00 +0000 (UTC) (envelope-from list_freebsd@bluerosetech.com) Received: from echo.brtsvcs.net (echo.brtsvcs.net [208.111.40.118]) (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 4GL0wv3vyxz4s0S for ; Thu, 8 Jul 2021 02:43:59 +0000 (UTC) (envelope-from list_freebsd@bluerosetech.com) Received: from chombo.houseloki.net (65-100-43-2.dia.static.qwest.net [65.100.43.2]) (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-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "chombo.houseloki.net", Issuer "brtsvcs.net CA" (verified OK)) by echo.brtsvcs.net (Postfix) with ESMTPS id 92BFC38D62; Thu, 8 Jul 2021 02:43:52 +0000 (UTC) Received: from [IPv6:2602:41:642b:630:f0a0:592d:acec:3c47] (unknown [IPv6:2602:41:642b:630:f0a0:592d:acec:3c47]) by chombo.houseloki.net (Postfix) with ESMTPSA id 315313314; Wed, 7 Jul 2021 19:43:50 -0700 (PDT) Subject: Re: Specifying IPv6 off-link for a subnet To: freebsd-lists-5@thismonkey.com References: From: Mel Pilgrim Cc: freebsd-questions@freebsd.org Message-ID: <5ea688b3-79b9-8a28-0430-5a4651207ae0@bluerosetech.com> Date: Wed, 7 Jul 2021 19:43:48 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 4GL0wv3vyxz4s0S X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=pass (mx1.freebsd.org: domain of list_freebsd@bluerosetech.com designates 208.111.40.118 as permitted sender) smtp.mailfrom=list_freebsd@bluerosetech.com X-Spamd-Result: default: False [-3.30 / 15.00]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; FROM_HAS_DN(0.00)[]; RBL_DBL_DONT_QUERY_IPS(0.00)[208.111.40.118:from]; R_SPF_ALLOW(-0.20)[+mx]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; TO_DN_NONE(0.00)[]; DMARC_NA(0.00)[bluerosetech.com]; SPAMHAUS_ZRD(0.00)[208.111.40.118:from:127.0.2.255]; RCVD_COUNT_THREE(0.00)[3]; TO_MATCH_ENVRCPT_SOME(0.00)[]; NEURAL_HAM_SHORT(-1.00)[-1.000]; RCPT_COUNT_TWO(0.00)[2]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:36236, ipnet:208.111.40.0/24, country:US]; RCVD_TLS_ALL(0.00)[]; MAILMAN_DEST(0.00)[freebsd-questions] X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 08 Jul 2021 02:44:00 -0000 On 2021-07-05 8:45, Scott wrote: > I have manually configured IPv6 on the interfaces: > ifconfig_vmx0_ipv6="inet6 xx::yy prefer_source accept_rtadv -autoconf no_radr" > > The prefix appears in the prefix list as: > # ndp -p > xx::/64 if=vmx0 > flags=LO vltime=infinity, pltime=infinity, expire=Never, ref=1 > No advertising router > > Here's the received RA: > 01:26:48.355186 IP6 (class 0xe0, hlim 255, next-header ICMPv6 (58) payload length: 64) fe80::1 > ff02::1: [icmp6 sum ok] ICMP6, router advertisement, length 64 > hop limit 64, Flags [none], pref high, router lifetime 1800s, reachable time 0ms, retrans timer 0ms > source link-address option (1), length 8 (1): 00:00:5e:00:02:02 > mtu option (5), length 8 (1): 9000 > prefix info option (3), length 32 (4): xx::/64, Flags [none], valid > time 3600s, pref. time 60s > > Note that there is no L flag set, so the prefix is off-link. You're misinterpreting what the L flag in a PIO means. If set, the L flag indicates the prefix can be used for on-link determination. But if the L bit is unset, the PIO isn't making any assertion about the prefix being on-link or off-link. More importantly, a host must not use a PIO with L=0 to conclude a prefix is off-link. IOW, it is correct for a host to do nothing when it receives an RA PIO with no flags for an already-configured prefix.