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Date:      Thu, 08 Jan 2009 20:04:03 -0500
From:      Bruce Walker <bmw@wezel.com>
To:        Peter Steele <psteele@maxiscale.com>
Cc:        freebsd-net@freebsd.org
Subject:   Re: Having problems with limited broadcast
Message-ID:  <4966A283.4070505@wezel.com>
In-Reply-To: <49668C71.4090407@FreeBSD.org>
References:  <2ACA3DE8F9758A48B8BE2C7A847F91F2479DF2@polaris.maxiscale.com>	<28b9b4180901070039x27a25bb4m6b50c8bfae63e0af@mail.gmail.com>	<2ACA3DE8F9758A48B8BE2C7A847F91F2479E9A@polaris.maxiscale.com>	<4964CA2E.5090708@wezel.com>	<2ACA3DE8F9758A48B8BE2C7A847F91F2479FB0@polaris.maxiscale.com>	<2ACA3DE8F9758A48B8BE2C7A847F91F2479FCE@polaris.maxiscale.com>	<d763ac660901081411l59120580yb4919a16b451e3ee@mail.gmail.com>	<2ACA3DE8F9758A48B8BE2C7A847F91F2479FD9@polaris.maxiscale.com> <49668C71.4090407@FreeBSD.org>

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Bruce M. Simpson wrote:
>
> The folk who point out that link-local addresses could be used, have 
> an interesting suggestion which might work for you.

Peter, I understand your issue with the (apparent) restriction of the 
169.254/16 range, though I'd point out that the IPv4-LL addressing 
scheme is considered a fall-back plan by most systems implementors.  
Your systems could look  for DHCP first then failing that, drop back to 
IPv4-LL and get an address.  The picky customers would simply be 
required to supply a DHCP server.  Everyone else presumably doesn't care 
as long as the boxes can communicate.


But there's another useful point to pickup from the ZeroConf stuff.  I 
implemented a small standalone IPv4-LLA daemon using libevent, libnet 
and libpcap.  IPv4-LLA needs to muck around with a completely 
unaddressed interface (like you are doing with your DHCP-lite), sending 
and listening-for broadcast and directed ARP packets, per RFC 3927.  It 
was trivial to do this in a completely portable way using libpcap and 
libnet.  I'd highly recommend to you that you link those libraries into 
your Python DHCP-lite app and you will be able to deploy relatively 
painlessly on any platform that those libraries are ported to.

http://sourceforge.net/projects/pylibpcap/
http://pylibnet.sourceforge.net/

Cheers!

-bmw



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