Date: Wed, 14 Jan 2004 15:06:10 +0100 From: Juan Rodriguez Hervella <jrh@it.uc3m.es> To: Luigi Rizzo <rizzo@icir.org>, net@freebsd.org Subject: Re: 'ipv6' type in /etc/protocols ? Message-ID: <200401141506.11400.jrh@it.uc3m.es> In-Reply-To: <20040114012913.A91612@xorpc.icir.org> References: <20040114012913.A91612@xorpc.icir.org>
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On Wednesday 14 January 2004 10:29, 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 ? I think that it makes sense if you want to parse IPv6 in IPv4 packets. > And in this case, > what name do we use for it to avoid conflicts ? Ipv6-encap ? ipv6-in-ipv4 ? ipv64 ? .....I dont know... I agree with you that if somebody specifies the word "Ipv6", what he/she wants to is to get normal IPv6 packets, not IPv6 in IPv4 packets....imho. > Looking at /sys/netinet/in.h, it appears that > ip_proto == 4 and 41 refer to encapsulations of ipv4 and ipv6 > into ip... You are right. -- ****** JFRH ****** In seeking the unattainable, simplicity only gets in the way. -- Epigrams in Programming, ACM SIGPLAN Sept. 1982
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