From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [RFC v2 2/4] net: enables interface option to skip IP Date: Tue, 25 Feb 2014 16:18:17 -0500 (EST) Message-ID: <20140225.161817.1623503840238501415.davem@davemloft.net> References: <1393266120.8041.19.camel@dcbw.local> <20140224.180426.411052665068255886.davem@davemloft.net> <1393362420.3032.8.camel@dcbw.local> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: mcgrof@do-not-panic.com, zoltan.kiss@citrix.com, netdev@vger.kernel.org, xen-devel@lists.xenproject.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, kuznet@ms2.inr.ac.ru, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net To: dcbw@redhat.com Return-path: In-Reply-To: <1393362420.3032.8.camel@dcbw.local> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Dan Williams Date: Tue, 25 Feb 2014 15:07:00 -0600 > Also, disable_ipv4 signals *intent*, which is distinct from current > state. > > Does an interface without an IPv4 address mean that the user wished it > not to have one? > > Or does it mean that DHCP hasn't started yet (but is supposed to), or > failed, or something hasn't gotten around to assigning an address yet? > > disable_ipv4 lets you distinguish between these two cases, the same way > disable_ipv6 does. Intent only matters on the kernel side if the kernel automatically assigns addresses to interfaces which have been brought up like ipv6 does. Since it does not do this for ipv4, this can be handled entirely in userspace. It is not a valid argument to say that a rogue dhcp might run on the machine and configure an ipv4 address. That's the admin's responsibility, and still a user side problem. A "rogue" program could just as equally turn the theoretical disable_ipv4 off too.