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From: Robert Watson <rwatson@FreeBSD.org>
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To: JINMEI Tatuya / =?ISO-2022-JP?B?GyRCP0BMQEMjOkgbKEI=?=
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Cc: freebsd-net@freebsd.org, Hideki Yamamoto <yamamoto436@oki.com>,
	freebsd-pf@freebsd.org
Subject: Re: IPv6 raw socket to send original udp
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On Tue, 16 May 2006, JINMEI Tatuya / [ISO-2022-JP] =BF=C0=CC=C0=C3=A3=BA=C8=
 wrote:

> So, if a program needs to specify an arbitrary source IPv6 address for=20
> outgoing packets, it should use other "packet injection" interface such a=
s=20
> BPF.

One problem with using BPF for packet injection in IPv4 is that it requires=
=20
the sender to provide the link layer encapsulation, make the routing decisi=
on,=20
and perform any address resolution.  Using raw sockets with the full header=
=20
option allows the sender to generate a datagram from an arbitrary source ye=
t=20
not perform those routing and link layer activities, which require more=20
intimate knowledge of the link type.  It might be desirable to add a socket=
=20
option to allow the specification of the source address in order to allow=
=20
packet replay tools, etc, to work without link layer knowledge.

Robert N M Watson
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