From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D659DC4338F for ; Wed, 18 Aug 2021 20:18:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B7E1A6109F for ; Wed, 18 Aug 2021 20:18:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233425AbhHRUSh (ORCPT ); Wed, 18 Aug 2021 16:18:37 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:36202 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229965AbhHRUSd (ORCPT ); Wed, 18 Aug 2021 16:18:33 -0400 Received: (from willy@localhost) by pcw.home.local (8.15.2/8.15.2/Submit) id 17IKHto2004917; Wed, 18 Aug 2021 22:17:55 +0200 Date: Wed, 18 Aug 2021 22:17:55 +0200 From: Willy Tarreau To: Thorsten Glaser Cc: Oleg , netdev@vger.kernel.org Subject: Re: ipv6 ::1 and lo dev Message-ID: <20210818201755.GA4899@1wt.eu> References: <20210818165919.GA24787@legohost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, Aug 18, 2021 at 07:47:37PM +0200, Thorsten Glaser wrote: > On Wed, 18 Aug 2021, Oleg wrote: > > > I try to replace ::1/128 ipv6 address on lo dev with ::1/112 to > > access more than 1 address(like with ipv4 127.0.0.1/8). But i get > > AIUI this is not possible in IPv6, only :: and ::1 are reserved, > the rest of ::/96 is IPv4-compatible IPv6 addresses. > > I never understood why you'd want more than one address for loopback > anyway (in my experience, the more addresses a host has, the more > confused it'll get about which ones to use for what). It's because you've probably never dealt with massive hosting :-) Sometimes binding a full /24 (or smaller) on the loopback, be it for listening addresses or to be used as sources to connect to next hops, is extremely useful. Willy