FAQ

KAME FAQ
$KAME: FAQ,v 1.33 2001/07/16 03:32:29 itojun Exp $


GENERAL
=======
Q: What is the KAME project?
	The KAME Project is a joint effort to create single solid software set,
	especially targeted at IPv6/IPsec.  Talented researchers from several
	Japanese major companies joined the project.  This joint effort will
	avoid unnecessary duplicated development in the same area, and
	effectively provides a high quality, advanced featured package. 

	The project aims to revamp BSD sys/net* tree, and:

	- to provide a FREE IPv6 protocol stack for research/commercial use.
	  (under BSD copyright)
	- to provide FREE IPsec to all over the world. (For free software,
	  crypto export from Japan seems to be legal.)
	- to provide FREE reference code for advanced internetworking.
	    (Advanced packet queuing, ATM, mobility, and whatever interesting.)

	To understand more about the KAME project itself, please proceed to
	http://www.kame.net/project-overview.html.

Q: How can I contribute?
	- Implement "ports" or "pkgsrc" for IPv6 apps
	  Sometimes nontrivial steps are needed to install IPv6 applications,
	  because IPv6 patches are redistributed separately from the original
	  application.  Please create FreeBSD/OpenBSD "ports", or NetBSD
	  "pkgsrc" and contribute those to *BSD projects.

	- Submit bug reports
	  PLEASE go through the top of http://www.kame.net/dev/send-pr.html
	  and supply enough information.

	- Review documents
	  Since the KAME core team does not have a native English speaker,
	  documents in English include many typos, wording mistakes,
	  and so forth.  We would be very grateful if you review our
	  documents and send us updates.

Q: What is the standard document the KAME code is based upon?
Which version of IPv6/IPsec does KAME support?
	The KAME project tries to support the latest specification possible.

	For list of currently-supported standard documents, please refer to
	IMPLEMENTATION in the distribution kit, or
	http://www.kame.net/dev/cvsweb.cgi/kame/IMPLEMENTATION.

Q: Why does KAME separate ping6 from ping (for IPv4), and traceroute6 from
   traceroute (for IPv4)?
	There have been many discussions on why we separate ping6(8)
	and ping(8).  Some people argued that it would be more
	convenient to uniform the ping command for both IPv4 and
	IPv6.  The followings are an answer to the request.

	From a developer's point of view: since the underlying raw socket API
	is totally different between IPv4 and IPv6, we would end
	up having two types of code base.  There would actually be
	less benefit to unify the two commands into a single
	command from the developer's standpoint.

	From an operator's point of view: unlike ordinary network
	applications like web, mail, and remote login tools, we are
	usually aware of address family when using network management
	tools.  We do not just want to know the reachability to the
	host, but want to know the reachability to the host via a
	particular network protocol such as IPv6.  Thus, even if we
	had a unified ping(8) command for both IPv4 and IPv6, we would
	usually type a -6 or -4 option (or something like those) to
	specify the particular address family.  This essentially means
	that we have two different commands.

Q: Are there other documents/FAQ lists I may want to check?
	- Depending on which BSD you are using, you will want to check the
	  project webpages, like http://www.openbsd.org/,
	  http://www.netbsd.org/, or http://www.freebsd.org/.
	- If you are using a KAME patch kit (like weekly snap, not the
	  integrated *BSD releases), you really need to go through all the
	  documents shipped in tar.gz.
	- http://www.kame.net/ has links to a set of good documents.
	- http://www.ipv6.org/, and http://www.jp.ipv6.org/ (if you can read
	  Japanese texts).
	- http://www.netbsd.org/Documentation/network/ipv6/

Q: Which operating systems/vendor routers use KAME stack?
	Operating systems:
	- OpenBSD, http://www.openbsd.org/
	- NetBSD, http://www.netbsd.org/
	- FreeBSD, http://www.freebsd.org/
	- BSD/OS, http://www.bsdi.com/
	- Apple Darwin

	Vendor routers:
	- Hitachi GR2000, http://www.v6.hitachi.co.jp/GR2000/
	- IIJ SEIL-T1, http://www.seil-t1.com/
	- (more)


INSTALLATION
============
Q: I heard that the *BSDs have integrated KAME code already.  Do I still need to
install KAME patches?
	Depends on your goal.  Roughly speaking,
	- If you want IPv6 for normal day-to-day use, you will be happy with
	  *BSD integrated code (no need for KAME patches).
	- If you want a bleeding-edge IPv6 code (including experimental and
	  unstable ones) you'd need to install KAME patches.

	http://www.kame.net/project-overview.html#release talks about this
	topic in more detail.

Q: I replaced the kernel and rebooted, and lost IPv4 connectivity.  Why?
	There are several possibilities, but it is almost always
	due to kernel configuration differences.  If you have
	been using a specific kernel configuration for your IPv4
	kernel, and you have installed a GENERIC.v6 kernel, you lost
	your special configurations.

	One good way to deal with this problem is to, (1) copy
	your original configuration file FOO into FOO.v6, (2)
	incorporate the difference between GENERIC and GENERIC.v6 into
	FOO.v6, (3) carefully look at FOO.v6 and configure a new
	kernel from that one.

Q: Is anything special required for network interface card drivers?
	(freebsd and bsdi) For efficient processing of IPv6 chained headers,
	KAME assumes the network driver will pass the packet to upper layers
	(IPv6 code), in the following form:

	(1) single internal mbuf
	(2) single external mbuf
	(3) multiple external mbufs

	Some of traditional drivers will pass the packet to upper layers in
	two linked internal mbufs.  In this case, the driver must be modified.
	You can check this situation by using netstat -sn.

	The modification is very simple.  You should check the use of MINCLSIZE
	in the driver, change that to MHLEN.  In this way you can avoid two
	linked internal mbufs.

	Multicast support is required for IPv6, since IPv6 uses
	multicast for hardware address (MAC address) resolution.
	Therefore, your network driver has to have multicast support,
	and have IFF_MULTICAST properly set.  Also be sure to check if
	the driver handles multicast ioctls, like SIOCADDMULTI.

	Even though it is better to have a hardware multicast packet
	filter, it is not mandatory; in most cases it is just fine
	to use promiscuous mode as the last resort, if there's no
	multicast packet filter support.


OPERATION AND PROGRAMMING
=========================
Q: /etc/rc scripts do not work after replacing vanilla *BSD kernel by KAME
kernel.
	/etc/rc scripts usually use tools in /sbin, like /sbin/ifconfig.
	In some cases, they do not work on a KAME kernel.  Be very sure to
	use tools in /usr/local/v6 instead.

	Note, however, depending on the ordering of /etc/rc initialization,
	/usr may not be ready when the network interfaces get initialized
	(for NFS-mounted /usr support).
	It may be safer to put network interface initialization into
	/etc/rc.local, and remove all network configurations from /etc/rc.conf
	and/or /etc/netstart.

Q: Why do link-local addresses in the kernel structure have
s6_addr16[1] filled?
	Due to the "scoped address" design in the IPv6 spec, the
	kernel must treat link-local addresses in a special manner.
	Link-local address has to be memorized with the incoming
	interface.  KAME uses s6_addr16[1] to keep the interface index
	(ifp->if_index) in the kernel structure.

	Note that this is only for internal kernel structures.
	Any data coming out of socket file descriptor is not
	affected.  KAME uses advanced API (rfc2292) for passing/getting
	interface index from/to userland.

	Also note that this hack may go away in the near future,
	by introduction of the sin6_ifindex field in sockaddr_in6
	structure.

	See the IMPLEMENTATION document for a full description.

Q: Does KAME support site-local addresses?
	Yes and no.

	KAME can handle site-local address, but it is not aware of
	the site boundary.  Therefore, KAME cannot become a site-border
	router.

	Site-local addressing (the spec itself, not KAME) has a
	bunch of issues/twists to be solved, such as site-border management
	and name servers.  We are trying very hard to solve them.

Q: How can I implement address-family independent applications?
Q: How can I modify my application to support IPv6 as well as IPv4?
	We have a short newsletter for that, titled "implementing AF-
	independent application".  Please visit
	http://www.kame.net/newsletter/19980604/.

	Craig Metz, "Protocol Independence Using the Sockets API",
	Proceedings of the freenix track: 2000 USENIX annual
	technical conference, June 2000.
	http://www.usenix.org/event/usenix2000/freenix/metzprotocol.html

Q: route6d dies with "IPV6_ADD_MEMBERSHIP" failure.
	This error occurs when you have configured an interface
	that is not capable of handling IPv6 packets.  This includes
	the slip interface (sl0) and some other interfaces.  Please
	remove those interfaces from the kernel configuration file.

Q: Which IPv6 routing daemon should I use?
	For easy installation, route6d (implemented by Akira Kato) is
	simple and easy-to-use, but not very configurable.

	For production use, try zebra from http://www.zebra.org/.

Q: How can I connect my host to the worldwide IPv6 network?
	Visit http://www.6bone.net/, all the information you need is there.

	http://www.kame.net/newsletter/19981224/ has detailed discussions
	on how you can be connected to 6bone.  It also has a cgi script to
	help you send a connection request.

Q: When I invoke ifconfig or netstat, garbled output is generated.
	I suspect that you are invoking old (original) ifconfig or netstat.

	Currently the KAME kit does not overwrite existing userland
	tools.  Instead, tools provided by KAME will be installed
	into /usr/local/v6/bin and alike.  Therefore, to use
	IPv6-enabled tools, you must invoke /usr/local/v6/sbin/ifconfig
	or such.  You can of course add /usr/local/v6/bin to your
	command search path.  Consult the manpage for your shell.

Q: How can I restrict RIPng route announcement for some of the interfaces?
	First of all, you should choose appropriate routing daemon.

	route6d (by Akira Kato) is designed to be simple and easy,
	so it has no configuration option for ignoring some of the
	interfaces.  You cannot use this for the purpose.

	hroute6d (contributed from Hitachi) has a very complex
	configuration file, which makes it possible to skip some
	of the interfaces.

	bgpd (contributed from Toshiba) also uses a configuration
	file.  You can specify not to listen and/or advertise RIPng
	messages on the specified interfaces.

	Other routing daemons (zebra/mrt/whatever) may have
	configuration options, so please refer to the document
	specific to the tool you chosen.

Q: I would like to configure IPsec for IPv4 only, and I do not need IPv6.
Is it possible to configure KAME for this?
	Of course, it should work.  Try configure a kernel without
	"options INET6".

	If it does not work well, add "options INET6" and ignore
	any IPv6 related things appear on messages/command
	options/whatever.  It is safe to ignore those things.

Q: IPv6 ping from other OSes does not seem to work.
	Are you using link-local address for that? (fe80::x) If
	so, be sure to clear the 2nd 16-bit field to 0.  KAME kernels
	use those bits internally, and some older versions of ifconfig show
	the value, but the value MUST NOT appear on the wire.

	If ifconfig command shows that your KAME host has the
	following address:

	fe80:1::x:y:z:u

	the address the host actually has is

	fe80::x:y:z:u

	Also, on many of existing operating systems, it is suggested (or even
	mandatory) to specify the outgoing link, when you try to ping
	(or ping6) link-local addresses.  This is to disambiguate link-local
	addresses on multiple links.

Q: How do I configure a IPv6-over-IPv4 tunnel?
	The simplest way to do this is to configure outer IPv4 address only, by
	the following command:

	hostA# gifconfig gif0 a.a.a.1 b.b.b.1

	hostB# gifconfig gif0 b.b.b.1 a.a.a.1

	As a gif interface has a link-local address, it is not
	necessary to configure inner IPv6 addresses.  Routing
	daemons will work just fine and packets will get forwarded
	between the two routers.  If you want to configure a global IPv6
	address on such a host, configure it to an ethernet interface.

	NOTE: on netbsd and openbsd, gifconfig is integrated into ifconfig(8).

Q: Some of my IPv6-ready programs show strange behavior after kernel update.
	As the IPv6 socket API is still an moving target, the KAME team
	sometimes have to change important structure definitions
	used in the socket API.  We have experienced changes in struct
	sockaddr_in6 several times already.

	If you have installed your IPv6-ready programs before the
	change, and the kernel is built from the KAME tree after
	the change, your programs will not work properly.  Be sure
	to update, or re-compile, userland tools too.

	We try to announce important changes to snap-users mailing
	list.  Please subscribe to snap-users mailing list, if you
	are willing to use SNAP kits.  See http://www.kame.net/snap-users/
	for detail.

Q: How do I configure IPsec?
	http://www.kame.net/newsletter/19980626/ covers the topic.

Q: I would like to connect from an IPv6-only host to an IPv4-only host.
	You MUST have a translator box between those two host, for
	protocol conversion.  http://www.kame.net/newsletter/19981001/
	covers the topic.

	socks64, which is a modified version of socks5, can be used
	so that IPv6-only host can make a proxy connection via a
	"socks64 server" on a dual-stack host.  For implementation
	please visit ftp://ftp.kame.net/pub/kame/misc/.

Q: How can I enable FAITH IPv6-to-IPv4 tcp relay?
	Please consult KAME faithd/README.* for details.

Q: How do I configure ATM PVC?
	KAME includes ATM PVC support, from the ALTQ package.  No SVC support is
	implemented.  A very limited variety of ATM cards are supported.

	http://www.kame.net/newsletter/19980701/ covers this topic
	(though it is a bit dated).

Q: I think I have problem with my tunnel; how do I track it?
	assume that your tunnel interface is "gif0".

	try: ping6 -I gif0 -n ff02::1

	If you get replies from two different nodes, your tunnel is
	working right.  It can be routing problem.  The two nodes
	are your node and the peer's node.

	If you get replies from single node only, you have a problem
	with your tunnel.  It could be a packet filter between your node
	and peer (like a firewall), IPv4 routing screwup, or anything.
	You need to make sure that IPv4 protocol # 41 goes through.
	If you have a packet filter blocking you, ask your network
	administrator to open up the filters.

	Another hint: always use "-n" when you try ping6 or
	traceroute6.  Reverse lookup timeouts can make it harder to track
	down.

Q: My operating system does not have gifconfig(8).
	On NetBSD and OpenBSD, gifconfig(8) is integrated into ifconfig(8),
	using the "tunnel" keyword (older OpenBSD releases use "giftunnel"
        keyword).

Q: I would like to know the merge status of KAME kit to *BSD.
	See http://www.kame.net/dev/cvsweb.cgi/kame/COVERAGE.

Q: How can I differentiate IPv6 http connections from IPv4 ones on my
web page?  (In other words, how can I provide dancing stuff for IPv6
users only, like www.kame.net?)
	If you are using an apache webserver, you can refer to environment
	variable REMOTE_ADDR to know the address of the client (in textual
	numeric representation).  For example, the following perl script
	fragment would print "IPv6 <address>" or "not IPv6 <address>"
	depending on the clients' address.

		if ($ENV{'REMOTE_ADDR'} =~ /^[a-fA-F0-9:]+$/) {
			print "IPv6 " . $ENV{'REMOTE_ADDR'} . "\n";
		} else {
			print "not IPv6 " . $ENV{'REMOTE_ADDR'} . "\n";
		}


LICENSE AND CRYPTO EXPORT
=========================
Q: What is the crypto export/import situation in Japan?
	NOTE: the following description does not reflect intentions
	of KAME participating companies, employers of KAME core
	team or KAME contributors, or such.  The KAME project and other
	parties are completely separate entity.  Please do not
	misinterpret.

	As far as I checked, there's no legal restriction for
	exporting/import crypto software, if it is done without
	fee.

	Japan seems to be in the Wassenaar agreement, and the Wassenaar
	agreement is reflected to the Japan's export/import control
	law.  It says that business parties must acquire approval
	for crypto export orders larger than 50000JPY.

	We checked with several attorneys to get answers which varied
	widely.  The answer reflected how aggressive/defensive the
	attorney is :-)

	See "crypto law survey page",
	http://cwis.kub.nl/~frw/people/koops/cls2.htm#ja, for more
	information. (the page is really great)

Q: Can I download KAME without infringing crypto law?
	The question can be separated into two parts: export from
	Japan and import to your country.

	For export from Japan, it looks that there's no restriction,
	for free software.  See faqomatic:37 for more info.

	For import to your country, please check "crypto law survey
	page" for your country.  Please proceed to
	http://cwis.kub.nl/~frw/people/koops/lawsurvy.htm.

Q: Under what kind of license is the KAME kit redistributed?
	The KAME kit itself obeys the following BSD-like AS-IS license.
	Contributed or derived software may under other license,
	so please look at each of the files.

	Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
	All rights reserved.

	Redistribution and use in source and binary forms, with or without
	modification, are permitted provided that the following conditions
	are met:
	1. Redistributions of source code must retain the above copyright
	   notice, this list of conditions and the following disclaimer.
	2. Redistributions in binary form must reproduce the above copyright
	   notice, this list of conditions and the following disclaimer in the
	   documentation and/or other materials provided with the distribution.
	3. Neither the name of the project nor the names of its contributors
	   may be used to endorse or promote products derived from this software
	   without specific prior written permission.

	THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
	ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
	FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	SUCH DAMAGE.


FUN STUFF
=========
Q: What is "KAME"?  Why did you choose the name?
	KAME is "turtle" in Japanese.  Then, you may wonder why it is
	"turtle"... :-)  See answers below.

	Official answer #1: Our office is located at Karigome
	village, Fujisawa, Kanagawa JAPAN.  Take the very first
	two letters and last two letters from KArigoME.  Yea, you
	got KAME.

	Official answer #2: In Asian/Indian mythology, the world
	is on a tray supported by elephants, and the elephants are
	on a giant turtle and a giant snake.  The universe consists
	of the turtle and the snake.  We are trying to shake the
	universe by our code, so the name is KAME.

	Real answer: We got together in IPv6 hacking workshop at
	JAIST university (http://www.jaist.ac.jp/).  One of core
	member, itojun, got very tired of tracking bugs.  There
	was big stuffed turtle (http://www.nui.org/Kame/) in the
	laboratory.  Itojun hugged the turtle and mumbled, "Mr
	turtle please help me debug my code...".
	(http://www.itojun.org/diary/19970930-1005/kame.html) This
	is the real reason for the name.