From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Lezcano Subject: Re: [PATCH 3/7 net-2.6.25] [IPV4]: Prohibit assignment of 0.0.0.0 as interface address. Date: Fri, 25 Jan 2008 15:48:05 +0100 Message-ID: <4799F6A5.7040703@fr.ibm.com> References: <1201269123-20378-1-git-send-email-den@openvz.org> <1201269123-20378-3-git-send-email-den@openvz.org> <4799EBBE.6080706@fr.ibm.com> <4799EE8C.60407@sw.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "Denis V. Lunev" , davem@davemloft.net, netdev@vger.kernel.org, devel@openvz.org, containers@lists.osdl.org To: "Denis V. Lunev" Return-path: Received: from mtagate3.de.ibm.com ([195.212.29.152]:53424 "EHLO mtagate3.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757227AbYAYOv0 (ORCPT ); Fri, 25 Jan 2008 09:51:26 -0500 Received: from d12nrmr1607.megacenter.de.ibm.com (d12nrmr1607.megacenter.de.ibm.com [9.149.167.49]) by mtagate3.de.ibm.com (8.13.8/8.13.8) with ESMTP id m0PEpP9N065416 for ; Fri, 25 Jan 2008 14:51:25 GMT Received: from d12av04.megacenter.de.ibm.com (d12av04.megacenter.de.ibm.com [9.149.165.229]) by d12nrmr1607.megacenter.de.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id m0PEpPYK1171504 for ; Fri, 25 Jan 2008 15:51:25 +0100 Received: from d12av04.megacenter.de.ibm.com (loopback [127.0.0.1]) by d12av04.megacenter.de.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m0PEpOsS011418 for ; Fri, 25 Jan 2008 15:51:24 +0100 In-Reply-To: <4799EE8C.60407@sw.ru> Sender: netdev-owner@vger.kernel.org List-ID: Denis V. Lunev wrote: > Daniel Lezcano wrote: >> Denis V. Lunev wrote: >>> I could hardly imagine why sombady needs to assign 0.0.0.0 as an >>> interface >>> address or interface destination address. The kernel will behave in a >>> strage >>> way in several places if this is possible, as ifa_local != 0 is >>> considered >>> as initialized/non-initialized state of the ifa. >> AFAICS, we should be able to set at an interface address to 0.0.0.0, in >> order to remove an IP address from an interface and keep this one up. >> I see two trivial cases: >> * remove the ipv4 on an interface but continue to use it through ipv6 >> * move ipv4 address from the interface to an attached bridge > > For this case there is an IOCTL/netlink "remove IP address". And I forgot to mention the general broadcast. This is need for the dhcp protocol. If you are not able to set your interface to 0.0.0.0, you will be not able to send a 255.255.255.255 broadcast message to have your IP address.