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Date:      Mon, 8 Jan 2007 13:36:36 +0300
From:      Eygene Ryabinkin <rea-fbsd@codelabs.ru>
To:        Tadaaki Nagao <nagao@iij.ad.jp>
Cc:        freebsd-net@freebsd.org, andre@FreeBSD.org, delphij@delphij.net
Subject:   Re: Different behavior of ping'ing INADDR_BROADCAST?
Message-ID:  <20070108103635.GI37482@codelabs.ru>
In-Reply-To: <20070108.175354.26933985.nagao@iij.ad.jp>
References:  <459D4D88.2030708@delphij.net> <20070105113442.GH37482@codelabs.ru> <20070105162022.GA1503@twilight.mbslab.kiae.ru> <20070108.175354.26933985.nagao@iij.ad.jp>

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Tadaaki, good day!

> This seems to be the same problem as kern/99558: "FreeBSD 6.1 can't send
> packets to INADDR_BROADCAST".
> 
> Maybe andre has some thoughts on how to fix this issue? (I'm CC'ing him.)

Exactly, thank you very much for the pointer!

> It seems to me from the PR above, that before patching `ping', ip_output.c
> should receive some sort of fix in handling INADDR_BROADCAST.

If ip_output.c will receive patching, it probably will be unneccessary to
patch `ping' ;)) The problem with ip_output.c patch is that it is rather
hard to spot the right interface to output the broadcast to: no pointers
are given when the packet just destined to 255.255.255.255. Probably
the best way will be to

- output it to all interfaces with broadcast capability,
- limit the TTL to 1.

The patch for `ping' introduces '-b' flag namely for the purpose of
identifying the interface the broadcast will go to.
-- 
Eygene



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