1 Configuring FAITH IPv6-to-IPv4 TCP relay 2 3 Kazu Yamamoto and Jun-ichiro itojun Hagino 4 $KAME: README,v 1.9 2002/05/09 14:10:06 itojun Exp $ 5 6 7 Introduction 8 ============ 9 10 FAITH is a IPv6-to-IPv4 TCP relay. It performs tcp relay just as some of 11 firewall-oriented gateway does, but between IPv6 and IPv4 with address 12 translation. 13 TCP connections has to be made from IPv6 node to IPv4 node. FAITH will 14 not relay connections for the opposite direction. 15 To perform relays, FAITH daemon needs to be executed on a router between 16 your local IPv6 site and outside IPv4 network. The daemon needs to be 17 invoked per each TCP services (TCP port number). 18 19 IPv4 node "dest" = 123.4.5.6 20 | 21 [[[[ outside IPv4 ocean ]]]] 22 | 23 node that runs FAITH-daemon (usually a router) 24 | 25 ==+=====+===+==== IPv6, or IPv4/v6 network in your site ^ 26 | | | connection 27 clients IPv6 node "src" | 28 29 You will have to allocate an IPv6 address prefix to map IPv4 addresses into. 30 The following description uses 3ffe:0501:ffff:0000:: as example. 31 Please use a prefix which belongs to your site. 32 FAITH will make it possible to make a IPv6 TCP connection From IPv6 node 33 "src", toward IPv4 node "dest", by specifying FAITH-mapped address 34 3ffe:0501:ffff:0000::123.4.5.6 35 (which is, 3ffe:0501:ffff:0000:0000:0000:7b04:0506). 36 The address mapping can be performed by hand:-), by special nameserver on 37 the network, or by special resolver on the source node. 38 39 40 Setup 41 ===== 42 43 The following example assumes: 44 - You have assigned 3ffe:0501:ffff:0000:: as FAITH adderss prefix. 45 - You are willing to provide IPv6-to IPv4 TCP relay for telnet. 46 47 <<On the translating router on which faithd runs>> 48 49 (1) If you have IPv6 TCP server for the "telnet" service, i.e. telnetd via 50 inet6d, disable that daemon. Comment out the line from "inet6d.conf" 51 and send the HUP signal to "inet6d". 52 53 (2) Execute sysctl as root to enable FAITH support in the kernel. 54 55 # sysctl -w net.inet6.ip6.keepfaith=1 56 57 (3) Route packets toward FAITH prefix into "faith0" interface. 58 59 # ifconfig faith0 up 60 # route add -inet6 3ffe:0501:ffff:0000:: -prefixlen 64 ::1 61 # route change -inet6 3ffe:0501:ffff:0000:: -prefixlen 64 -ifp faith0 62 63 (4) Execute "faithd" by root as follows: 64 65 # faithd telnet /usr/libexec/telnetd telnetd 66 67 1st argument is a service name you are willing to provide TCP relay. 68 (it can be specified either by number "23" or by string "telnet") 69 2nd argument is a path name for local IPv6 TCP server. If there is a 70 connection toward the router itself, this program will be invoked. 71 3rd and the following arguments are arguments for the local IPv6 TCP 72 server. (3rd argument is typically the program name without its path.) 73 74 More examples: 75 76 # faithd ftpd /usr/libexec/ftpd ftpd -l 77 # faithd sshd 78 79 If inetd(8) on your platform have special support for faithd, it is possible 80 to setup faithd services via inetd(8). Consult manpage for details. 81 82 83 <<Routing>> 84 85 (4) Make sure that packets whose destinations match the prefix can 86 reach from the IPv6 host to the translating router. 87 88 <<On the IPv6 host>> 89 90 There are two ways to translate IPv4 address to IPv6 address: 91 (a) Faked by DNS 92 (b) Faked by /etc/hosts. 93 94 (5.a) Install "newbie" and set up FAITH mode. See kit/ports/newbie. 95 96 (5.b) Add an entry into /etc/hosts so that you can resolve hostname into 97 faked IPv6 address. For example, add the following line for 98 www.NetBSD.org: 99 100 3ffe:0501:ffff:0000::140.160.140.252 www.NetBSD.org 101 102 <<On the translating router on which faithd runs.>> 103 104 (6) To see if "faithd" works, watch "/var/log/daemon". Note: please 105 setup "/etc/syslog.conf" so that LOG_DAEMON messages are to be stored 106 in "/var/log/daemon". 107 108 <e.g.> 109 daemon.* /var/log/daemon 110 111 112 Access control 113 ============== 114 115 Since faithd implements TCP relaying service, it is critical to implement 116 proper access control to cope with malicious use. Bad guy may try to 117 use your relay router to circumvent access controls, or may try to 118 abuse your network (like sending SPAMs from IPv4 address that belong to you). 119 Install IPv6 packet filter directives that would reject traffic from 120 unwanted source. If you are using inetd-based setup, you may be able to 121 use access control mechanisms in inetd. 122 123 124 Advanced configuration 125 ====================== 126 127 If you would like to restrict IPv4 destination for translation, you may 128 want to do the following: 129 130 # route add -inet6 3ffe:0501:ffff:0000::123.0.0.0 -prefixlen 104 ::1 131 # route change -inet6 3ffe:0501:ffff:0000::123.0.0.0 -prefixlen 104 \ 132 -ifp faith0 133 134 By this way, you can restrict IPv4 destination to 123.0.0.0/8. 135 You may also want to reject packets toward 3ffe:0501:ffff:0000::/64 which 136 is not in 3ffe:0501:ffff:0000::123.0.0.0/104. This will be left as excerside 137 for the reader. 138 139 By doing this, you will be able to provide your IPv4 web server to outside 140 IPv6 customers, without risks of unwanted open relays. 141 142 [[[[ IPv6 network outside ]]]] | 143 | | connection 144 node that runs FAITH-daemon (usually a router) v 145 | 146 ========+======== IPv4/v6 network in your site 147 | (123.0.0.0/8) 148 IPv4 web server 149
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