From owner-freebsd-net@freebsd.org Thu Jan 4 17:28:38 2018 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 0B394EA77F2 for ; Thu, 4 Jan 2018 17:28:38 +0000 (UTC) (envelope-from karl@denninger.net) Received: from colo1.denninger.net (colo1.denninger.net [67.205.158.196]) by mx1.freebsd.org (Postfix) with ESMTP id BD35E74E66 for ; Thu, 4 Jan 2018 17:28:37 +0000 (UTC) (envelope-from karl@denninger.net) Received: from denninger.net (ip68-1-57-197.pn.at.cox.net [68.1.57.197]) by colo1.denninger.net (Postfix) with ESMTP id C740427502 for ; Thu, 4 Jan 2018 12:28:07 -0500 (EST) Received: from [192.168.10.23] (D13.Denninger.Net [192.168.10.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by denninger.net (Postfix) with ESMTPSA id E469F1080EC for ; Thu, 4 Jan 2018 11:28:05 -0600 (CST) Subject: Re: IP networking single socket, both IPv4 and V6? To: freebsd-net@freebsd.org References: <2b3944fc-df1a-9998-876e-ad74f8cc073d@denninger.net> From: Karl Denninger Message-ID: <1d904614-1a3e-bfae-d8d4-843faf528be3@denninger.net> Date: Thu, 4 Jan 2018 11:28:02 -0600 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-512; boundary="------------ms010806010102080303090803" X-Content-Filtered-By: Mailman/MimeDel 2.1.25 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 04 Jan 2018 17:28:38 -0000 This is a cryptographically signed message in MIME format. --------------ms010806010102080303090803 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 1/4/2018 10:32, Lewis Donzis wrote: > On Jan 4, 2018, at 10:17 AM, Karl Denninger wrote:= >> I've written a fair bit of code that binds to both Ipv4 and v6 for >> incoming connections, using two sockets (one for each.) >> >> Perusing around the 'net I see an implementation note written by IBM >> that implies that on their Unix implementation you can set up an INET6= >> listener and it will open listeners on *both* IPv4 and v6; you code it= >> as an Ipv6 socket/bind/listen/accept, and if an Ipv4 connection comes = in >> you get a prefix'd IPv4 address back when you call getpeername(). >> >> This would obviously shorten up code and remove the need to open the >> second listener socket, but playing with this on FreeBSD it doesn't >> appear to work -- I only get the IPv6 listener in "netstat -a -n" >> showing up and as expected a connection to a v4 address on that port >> fails (refused, since there's no listener.) >> >> Is this something that *should* work on FreeBSD? > It works. We do it all the time. You either have to set the sysctl: > > net.inet6.ip6.v6only=3D0 > > which you can do in /etc/sysctl.conf or with the sysctl utility, or, in= your program, use setsockopt to turn off the V6ONLY option, e.g.: > > setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, &(int){0}, sizeof (int)); /= / Turn off v6-only > > We use the first method, which is broken in FreeBSD 11.1 prior to patch= level 5 or 6, I can=E2=80=99t remember which, but works in all others. = The second method is considered to be more portable. > > FWIW, Linux, by default, sets v6only off, so it doesn't require anythin= g special. > Well that explains why it didn't work as expected... thanks :-) --=20 Karl Denninger karl@denninger.net /The Market Ticker/ /[S/MIME encrypted email preferred]/ --------------ms010806010102080303090803 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature 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