From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian Haley Subject: Re: [Bugme-new] [Bug 15720] New: IPv6's ipv4-compatibility addresses don't bind Date: Tue, 13 Apr 2010 11:06:38 -0400 Message-ID: <4BC4887E.1050801@hp.com> References: <20100412212241.d8bf4185.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Andrew Morton , netdev@vger.kernel.org, bugzilla-daemon@bugzilla.kernel.org, bugme-daemon@bugzilla.kernel.org To: charles@kde.org Return-path: Received: from g1t0026.austin.hp.com ([15.216.28.33]:12038 "EHLO g1t0026.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752545Ab0DMPGn (ORCPT ); Tue, 13 Apr 2010 11:06:43 -0400 In-Reply-To: <20100412212241.d8bf4185.akpm@linux-foundation.org> Sender: netdev-owner@vger.kernel.org List-ID: Andrew Morton wrote: >> When attempting to bind to an address using ipv4-compatibility, for example, >> "::ffff:127.0.0.1", Linux refuses to bind to that address when >> /proc/sys/net/ipv6/bindv6only is set. This is actually not a (deprecated) IPv4-compatible IPv6 address (::127.0.0.1), but an IPv4-mapped IPv6 address. >> It seems to me that the intent of "bindv6only" was to not bind to the ipv4 >> address when you bind to all addresses (specifically ipv6 address "::"). So >> when you bind to ::, an ipv4 client connects to you, and it appears to be >> connecting from ::ffff:192.168.5.5. I don't think its intent was to effectively >> disable binding to ::ffff:x.x.x.x addresses - just breaking that feature makes >> no sense. It is documented in ip-sysctl.txt: bindv6only - BOOLEAN Default value for IPV6_V6ONLY socket option, which restricts use of the IPv6 socket to IPv6 communication only. TRUE: disable IPv4-mapped address feature FALSE: enable IPv4-mapped address feature Default: FALSE (as specified in RFC2553bis) -Brian