From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ido Schimmel Subject: Re: 4.14.(44->48) IPv6 RA issue? Date: Mon, 18 Jun 2018 22:09:26 +0300 Message-ID: <20180618190926.GA18065@splinter> References: <35958.1529334166@turing-police.cc.vt.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: valdis.kletnieks@vt.edu Return-path: Content-Disposition: inline In-Reply-To: <35958.1529334166@turing-police.cc.vt.edu> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mon, Jun 18, 2018 at 11:02:46AM -0400, valdis.kletnieks@vt.edu wrote: > So I'm trying to troubleshoot an issue on an OpenWRT/Lede based > router, where IPv6 connectivity totally fails. I've bisected it down to: > > git log --oneline 187da94808a634477b5e5a69109ea0c566dfa64b..73d8a6ab7668173d70adbed45b61be5256c505e > 73d8a6ab7668 (refs/bisect/bad) base-files: fix UCI config parsing and callback handling > e52f3e9b1376 kernel: bump 4.14 to 4.14.48 > 7590c3c58f5e (HEAD) scripts: Replace obsolete POSIX tmpnam in slugimage.pl with File::Temp function > 987900f2de76 hostapd: properly build hostapd-only SSL variants > > and am pretty sure that it's the kernel bump (works with a 4.14.44 kernel, > breaks with 4.14.48) as the other 3 commits don't go anywhere near IPv6 handling. ... > Note that eth1 is the uplink towards my ISP. I've pointed a 'tcpdump -n -i eth1 ip6' > at it, and see plenty of RA packets come in, but neighbor discovery never completes. > Looking at the Changelogs for .45->.50 don't show any smoking-gun patches. > > This ring any bells, before I delve deeper into it? If this is a router and forwarding is enabled, then you need to set 'accept_ra' to '2' [1]. Is this what you have configured? Seems that OpenWRT recently started to explicitly set 'accept_ra' to '0' [2]. 1. https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt 2. https://github.com/openwrt/openwrt/commit/bb46520159c0119e829900e29681feea6f297fe0