Date: Wed, 14 Jan 2004 11:58:14 +0200 From: John Hay <jhay@icomtek.csir.co.za> To: Luigi Rizzo <rizzo@icir.org> Cc: net@freebsd.org Subject: Re: 'ipv6' type in /etc/protocols ? Message-ID: <20040114095814.GA96762@zibbi.icomtek.csir.co.za> In-Reply-To: <20040114012913.A91612@xorpc.icir.org> References: <20040114012913.A91612@xorpc.icir.org>
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On Wed, Jan 14, 2004 at 01:29:13AM -0800, Luigi Rizzo wrote:
> hi,
> in implementing ipv6 support for ipfw2, i hit the following
> problem: /etc/protocols has an entry:
>
> ipv6 41 IPV6 # ipv6
>
> which is somewhat confusing for the parser -- if you
> type something like
>
> ipfw add allow ipv6 from foo to bar
>
> the "ipv6" will match in the call to getprotobyname() and
> the above will be translated into a rule that matches packets with
> ip->ip_proto == 41 (6 is TCP, 17 is UDP, etc.), while i presume
> that what one would really want with the above notation is to
> match IPv6 packets, i.e.
>
> + layer2 packets with mac-type 0x86dd (ipv6)
> + layer3 packets with ip->ip_v == 6
>
> Now, i can put a special case for the keyword 'ipv6', but
> I wonder, what do we do with ip->ip_proto == 41 ? Does it
> make sense to handle this request ? And in this case,
> what name do we use for it to avoid conflicts ?
> Looking at /sys/netinet/in.h, it appears that
> ip_proto == 4 and 41 refer to encapsulations of ipv4 and ipv6
> into ip...
That is used when transporting IPv6 packets over parts of the network
that doesn't have native IPv6 support. It is used when configuring a
gif(4) tunnel for instance:
ifconfig gif0
gif0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1280
tunnel inet xxx.xx.8.68 --> xxx.xx.223.30
inet6 fe80::290:27ff:fe06:5b24%gif0 prefixlen 64 scopeid 0x5
John
--
John Hay -- John.Hay@icomtek.csir.co.za / jhay@FreeBSD.org
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