From owner-freebsd-net@freebsd.org Tue May 10 16:30:34 2016 Return-Path: Delivered-To: freebsd-net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 16A0BB364F0 for ; Tue, 10 May 2016 16:30:34 +0000 (UTC) (envelope-from jinmei.tatuya@gmail.com) Received: from mail-ig0-x22c.google.com (mail-ig0-x22c.google.com [IPv6:2607:f8b0:4001:c05::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id D6D6E1B5D for ; Tue, 10 May 2016 16:30:33 +0000 (UTC) (envelope-from jinmei.tatuya@gmail.com) Received: by mail-ig0-x22c.google.com with SMTP id lr7so14550518igb.1 for ; Tue, 10 May 2016 09:30:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc; bh=uBxGK5cpJlS5wvubGRmeFlxUWmsWH7eZkpoz6lxLBLs=; b=Gvs77e6ge3ea96yBGdb2Yph2+kx5961FFKQkabEeTvjPAiWpnKOf2HbERxI6bJNUbk RfE0XlGwNq26thM2HAQScGxuauMiBpgLyB9c0XZ5Zxug/dUhL5kIgkwyqWa/kVI1wc65 ZzAkm+l4ikM7Im6VoNuH2IL30f7Rv8geZrtipuSqy2W2S4JclvFzDcoUaTaUCTqSTEPX Yop9OVNLPRMFFb9eqCqLAMMhsYVp9F0tc0K5Y5YZ3yj/8NoueMvfqV7RP+n3NqVye3oi mwIA81HjPXV61T40FWFOD6/2GGGWgvWtSdLStDA0u8SwlT3X1asL+lrr7Ugla2/m9wuX N5Ww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:sender:in-reply-to:references:date :message-id:subject:from:to:cc; bh=uBxGK5cpJlS5wvubGRmeFlxUWmsWH7eZkpoz6lxLBLs=; b=ZnFsZ4BkXr4mfMwJmczDhMIs4MSqy8eTjoLScu9HWKeI/7egpRMdvq2mcdt+dwMaJ8 enRqHLHPr3I3YkZqippQ3M6CpyzAFL/A8ulHr9AQyWhO1Q4H8aLE14WBzX7J1KxJsNOj cczRfvRqwk9Thm0vDzzeIq4UdQWeF4QiGeNi2V4m2c09c56jwRsb3XO+HlG72KqewLLY RAqQKJAqZDhq5MyjwOc8nyxxVZAtIr2zFARyqsXKE5b6S+JSzQAsyJyFpl4fgfVz925y 0uxXubvlWPry+Iw+esVMAE71xVRxCt/BLqQ9hGUmFFA0yGHuf6AjihaY1iDXCW9Hy9jb dxfg== X-Gm-Message-State: AOPr4FWNe8kii3uUgOBaM0baNs2umgWyUFd7Dwb6qmbw+AYWKy49bVslZc9mNvz23+l76H7khw+uDhN3lAe9JA== MIME-Version: 1.0 X-Received: by 10.50.100.135 with SMTP id ey7mr16824219igb.41.1462897833157; Tue, 10 May 2016 09:30:33 -0700 (PDT) Sender: jinmei.tatuya@gmail.com Received: by 10.107.19.218 with HTTP; Tue, 10 May 2016 09:30:33 -0700 (PDT) In-Reply-To: References: Date: Tue, 10 May 2016 09:30:33 -0700 X-Google-Sender-Auth: uWQ-VqQD01W-n1VX2jkl0ZqGIeM Message-ID: Subject: Re: ping6: failed to get receiving hop limit From: =?UTF-8?B?56We5piO6YGU5ZOJ?= To: Dmitry Sivachenko Cc: FreeBSD Net Content-Type: text/plain; charset=UTF-8 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 May 2016 16:30:34 -0000 At Tue, 10 May 2016 10:26:59 +0300, Dmitry Sivachenko wrote: > Sometimes ping6 command writes the following warning to stderr: > > ping6: failed to get receiving hop limit > > I can easily reproduce this with > for n in `jot - 1 1000` ; do /sbin/ping6 -n -c 5 $HOST > /dev/null ; done > > It is very likely that even 100 repetitions is enough to catch this. > > Other than this warning IPv6 network seems to work properly. > > What does it mean? That should mean the IPV6_RECVHOPLIMIT socket option somehow didn't work as expected: the kernel didn't provide the information in the ancillary data chain. I have no idea about how this could happen - it's quite likely to be some kind of kernel bug, but I have no specific idea. -- JINMEI, Tatuya