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150 lines
5.0 KiB
Plaintext
150 lines
5.0 KiB
Plaintext
Configuring FAITH IPv6-to-IPv4 TCP relay
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Kazu Yamamoto and Jun-ichiro itojun Hagino
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$KAME: README,v 1.8 2001/09/05 03:04:20 itojun Exp $
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$FreeBSD$
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Introduction
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============
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FAITH is an IPv6-to-IPv4 TCP relay. It performs tcp relay just as some of
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firewall-oriented gateway does, but between IPv6 and IPv4 with address
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translation.
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TCP connections has to be made from IPv6 node to IPv4 node. FAITH will
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not relay connections for the opposite direction.
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To perform relays, FAITH daemon needs to be executed on a router between
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your local IPv6 site and outside IPv4 network. The daemon needs to be
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invoked per each TCP services (TCP port number).
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IPv4 node "dest" = 123.4.5.6
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[[[[ outside IPv4 ocean ]]]]
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node that runs FAITH-daemon (usually a router)
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==+=====+===+==== IPv6, or IPv4/v6 network in your site ^
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| | | connection
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clients IPv6 node "src" |
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You will have to allocate an IPv6 address prefix to map IPv4 addresses into.
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The following description uses 3ffe:0501:ffff:0000:: as example.
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Please use a prefix which belongs to your site.
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FAITH will make it possible to make an IPv6 TCP connection From IPv6 node
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"src", toward IPv4 node "dest", by specifying FAITH-mapped address
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3ffe:0501:ffff:0000::123.4.5.6
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(which is, 3ffe:0501:ffff:0000:0000:0000:7b04:0506).
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The address mapping can be performed by hand:-), by special nameserver on
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the network, or by special resolver on the source node.
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Setup
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=====
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The following example assumes:
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- You have assigned 3ffe:0501:ffff:0000:: as FAITH adderss prefix.
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- You are willing to provide IPv6-to IPv4 TCP relay for telnet.
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<<On the translating router on which faithd runs>>
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(1) If you have IPv6 TCP server for the "telnet" service, i.e. telnetd via
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inet6d, disable that daemon. Comment out the line from "inet6d.conf"
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and send the HUP signal to "inet6d".
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(2) Execute sysctl as root to enable FAITH support in the kernel.
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# sysctl net.inet6.ip6.keepfaith=1
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(3) Route packets toward FAITH prefix into "faith0" interface.
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# ifconfig faith0 up
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# route add -inet6 3ffe:0501:ffff:0000:: -prefixlen 64 ::1
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# route change -inet6 3ffe:0501:ffff:0000:: -prefixlen 64 -ifp faith0
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(4) Execute "faithd" by root as follows:
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# faithd telnet /usr/libexec/telnetd telnetd
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1st argument is a service name you are willing to provide TCP relay.
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(it can be specified either by number "23" or by string "telnet")
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2nd argument is a path name for local IPv6 TCP server. If there is a
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connection toward the router itself, this program will be invoked.
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3rd and the following arguments are arguments for the local IPv6 TCP
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server. (3rd argument is typically the program name without its path.)
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More examples:
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# faithd login /usr/libexec/rlogin rlogind
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# faithd shell /usr/libexec/rshd rshd
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# faithd ftpd /usr/libexec/ftpd ftpd -l
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# faithd sshd
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If inetd(8) on your platform have special support for faithd, it is possible
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to setup faithd services via inetd(8). Consult manpage for details.
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<<Routing>>
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(4) Make sure that packets whose destinations match the prefix can
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reach from the IPv6 host to the translating router.
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<<On the IPv6 host>>
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There are two ways to translate IPv4 address to IPv6 address:
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(a) Faked by DNS
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(b) Faked by /etc/hosts.
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(5.a) Install "newbie" and set up FAITH mode. See kit/ports/newbie.
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(5.b) Add an entry into /etc/hosts so that you can resolve hostname into
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faked IPv6 addrss. For example, add the following line for www.netbsd.org:
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3ffe:0501:ffff:0000::140.160.140.252 www.netbsd.org
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<<On the translating router on which faithd runs.>>
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(6) To see if "faithd" works, watch "/var/log/daemon". Note: please
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setup "/etc/syslog.conf" so that LOG_DAEMON messages are to be stored
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in "/var/log/daemon".
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<e.g.>
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daemon.* /var/log/daemon
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Access control
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==============
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Since faithd implements TCP relaying service, it is critical to implement
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proper access control to cope with malicious use. Bad guy may try to
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use your relay router to circumvent access controls, or may try to
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abuse your network (like sending SPAMs from IPv4 address that belong to you).
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Install IPv6 packet filter directives that would reject traffic from
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unwanted source. If you are using inetd-based setup, you may be able to
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use access control mechanisms in inetd.
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Advanced configuration
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======================
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If you would like to restrict IPv4 destination for translation, you may
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want to do the following:
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# route add -inet6 3ffe:0501:ffff:0000::123.0.0.0 -prefixlen 104 ::1
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# route change -inet6 3ffe:0501:ffff:0000::123.0.0.0 -prefixlen 104 \
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-ifp faith0
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By this way, you can restrict IPv4 destination to 123.0.0.0/8.
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You may also want to reject packets toward 3ffe:0501:ffff:0000::/64 which
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is not in 3ffe:0501:ffff:0000::123.0.0.0/104. This will be left as excerside
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for the reader.
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By doing this, you will be able to provide your IPv4 web server to outside
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IPv6 customers, without risks of unwanted open relays.
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[[[[ IPv6 network outside ]]]] |
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| | connection
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node that runs FAITH-daemon (usually a router) v
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========+======== IPv4/v6 network in your site
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| (123.0.0.0/8)
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IPv4 web server
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