From owner-freebsd-net@freebsd.org  Thu Aug 18 21:43:11 2016
Return-Path: <owner-freebsd-net@freebsd.org>
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 EC16DBBFC9D
 for <freebsd-net@mailman.ysv.freebsd.org>;
 Thu, 18 Aug 2016 21:43:11 +0000 (UTC) (envelope-from paul@prt.org)
Received: from smtp3.mail.clearhost.co.uk (smtp3.mail.clearhost.co.uk
 [IPv6:2001:1420::25:103])
 (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
 (Client CN "*.mail.clearhost.co.uk", Issuer "RapidSSL CA" (not verified))
 by mx1.freebsd.org (Postfix) with ESMTPS id BB8891911
 for <freebsd-net@freebsd.org>; Thu, 18 Aug 2016 21:43:11 +0000 (UTC)
 (envelope-from paul@prt.org)
Received: from [2001:1420:a:105:c62c:3ff:fe2f:bf] (port=50867
 helo=parsnip.heronsbrook.org.uk)
 by smtp3.mail.clearhost.co.uk with esmtpsa (TLSv1:AES128-SHA:128)
 (Exim 4.76 (FreeBSD)) (envelope-from <paul@prt.org>)
 id 1baV5g-000MGl-Vd
 for freebsd-net@freebsd.org; Thu, 18 Aug 2016 21:43:09 +0000
Subject: Re: How can I send packets to 255.255.255.255 from the command line?
To: freebsd-net@freebsd.org
References: <CAFMmRNwXKhNUg35eYS4bE4UZQxTrAhYDatnokDuMtTT33SUMwQ@mail.gmail.com>
 <20160818204822.GB18759@workvm.myhome>
 <CAFMmRNzG_Xo=D0szCSv3=SBnZEiKmsv3arw=32k1dSoftnRR_w@mail.gmail.com>
From: Paul Thornton <paul@prt.org>
Message-ID: <6bc1bbb9-c530-92bc-8e26-6d4ca7e4ecb9@prt.org>
Date: Thu, 18 Aug 2016 22:43:36 +0100
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:45.0)
 Gecko/20100101 Thunderbird/45.1.0
MIME-Version: 1.0
In-Reply-To: <CAFMmRNzG_Xo=D0szCSv3=SBnZEiKmsv3arw=32k1dSoftnRR_w@mail.gmail.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net/>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 18 Aug 2016 21:43:12 -0000

On 18/08/2016 21:55, Ryan Stone wrote:
> On Thu, Aug 18, 2016 at 4:48 PM, Paul A. Procacci <pprocacci@datapipe.com>
> wrote:
>
>> You should be able to ping the local subnet.
>> Alternatively you can use net/arping.
>>
>> ~Paul
>>
>
> I'm specifically looking to test the handling of 255.255.255.255, so a
> local broadcast address is out.  Unfortunately, arping doesn't seem to do
> the right thing on FreeBSD.  It manages to get the kernel to try arp'ing
> for 255.255.255.255.

This very likely comes under the heading of "horrible bodges" but when I 
needed to do this, after much experimenting I added a static route to 
255.255.255.0/24 pointing to the local LAN broadcast address.

For example, on a machine with address 192.168.10.10/24 the "fix" would be:
route add 255.255.255.0/24 192.168.10.255

My code could then happily send UDP to 255.255.255.255 without issue, 
and the packets make it out onto the wire with a broadcast destination 
MAC address.

This was under 10.1-RELEASE; things may have changed that make it no 
longer work.

I did warn you that it came under the heading of "horrible bodges" :)

Paul.