From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx.spodhuis.org (smtp.spodhuis.org [IPv6:2a02:898:31:0:48:4558:736d:7470]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 9746121F0AE for ; Tue, 22 Jan 2013 23:24:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=spodhuis.org; s=d201210; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date; bh=QOplkfhDcGM91P+DmXJuvRbVf1eNUXtCpG7XoMfZRJg=; b=B5coru8EatYE2zoKwKRpSrD7IqfGqZOSNNMGopklIytzOkJXxwTGzIUtrnxRViw9exVR+hBFcnVB8+P9MeL0FnEhxzIMfCeU8tdvw824Y9XVjP89htoxYFw/xlTswuwJJin7Bj2a1qdV3cvXVOKnfIBJ3Y1oHWxxxq9cNmi8CgY=; Received: from authenticated user by smtp.spodhuis.org with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) id 1Txuh1-000HAy-PU; Wed, 23 Jan 2013 07:24:19 +0000 Date: Wed, 23 Jan 2013 02:24:18 -0500 From: Phil Pennock To: Chris Lawrence Message-ID: <20130123072418.GA65889@redoubt.spodhuis.org> Mail-Followup-To: Chris Lawrence , Dave Taht , "" References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Cc: "" Subject: Re: [Cerowrt-devel] dnsmasq ipv6 stuff X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 23 Jan 2013 07:24:22 -0000 On 2013-01-22 at 19:14 -0500, Chris Lawrence wrote: > True, although I think that's pretty much unavoidable given the design > of ipv6 though (isn't ::1 always the router for the subnet)? No, the router can have any IP within that subnet, but it will also join various multicast groups. Link-local multicast is ff02:: and the ::2 address is "all routers", so given "se00" as a network device name: ping6 ff02::2%se00 should elicit a response from every device on the LAN connected to CeroWRT's first LAN interface, where the device thinks that it's a router. Within the multicast assignments (ff0X::) ::1 is all nodes, so ping6 ff02::1%se00 gets a response from every machine which has IPv6 configured up, assuming no packet filters. This is defined for ff0X for X with 1, 2 and 5 (interface-local (ie, this machine), link-local and site-local). Fortunately, IPv6 doesn't define this for the global scope, ff0e::, otherwise there would be a teensy amplification factor for a response to a spoofed ICMP source address sending a ping to ff0e::1. For CeroWRT and debugging, the other interesting address in ff02:: (so you need the %device scoping control on the address) is ff02::1:2 for All_DHCP_Relay_Agents_and_Servers. -Phil