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diff --git a/README_FILES/IPV6_README b/README_FILES/IPV6_README new file mode 100644 index 0000000..872756e --- /dev/null +++ b/README_FILES/IPV6_README @@ -0,0 +1,264 @@ +PPoossttffiixx IIPPvv66 SSuuppppoorrtt + +------------------------------------------------------------------------------- + +IInnttrroodduuccttiioonn + +Postfix 2.2 introduces support for the IPv6 (IP version 6) protocol. IPv6 +support for older Postfix versions was available as an add-on patch. The +section "Compatibility with Postfix <2.2 IPv6 support" below discusses the +differences between these implementations. + +The main feature of interest is that IPv6 uses 128-bit IP addresses instead of +the 32-bit addresses used by IPv4. It can therefore accommodate a much larger +number of hosts and networks without ugly kluges such as NAT. A side benefit of +the much larger address space is that it makes random network scanning +impractical. + +Postfix uses the same SMTP protocol over IPv6 as it already uses over the older +IPv4 network, and does AAAA record lookups in the DNS in addition to the older +A records. Information about IPv6 can be found at http://www.ipv6.org/. + +This document provides information on the following topics: + + * Supported platforms + * Configuration + * Known limitations + * Compatibility with Postfix <2.2 IPv6 support + * IPv6 Support for unsupported platforms + * Credits + +SSuuppppoorrtteedd PPllaattffoorrmmss + +Postfix version 2.2 supports IPv4 and IPv6 on the following platforms: + + * AIX 5.1+ + * Darwin 7.3+ + * FreeBSD 4+ + * Linux 2.4+ + * NetBSD 1.5+ + * OpenBSD 2+ + * Solaris 8+ + * Tru64Unix V5.1+ + +On other platforms Postfix will simply use IPv4 as it has always done. + +See below for tips how to port Postfix IPv6 support to other environments. + +CCoonnffiigguurraattiioonn + +Postfix IPv6 support introduces two new main.cf configuration parameters, and +introduces an important change in address syntax notation in match lists such +as mynetworks or debug_peer_list. + +Postfix IPv6 address syntax is a little tricky, because there are a few places +where you must enclose an IPv6 address inside "[]" characters, and a few places +where you must not. It is a good idea to use "[]" only in the few places where +you have to. Check out the postconf(5) manual whenever you do IPv6 related +configuration work with Postfix. + + * Instead of hard-coding 127.0.0.1 and ::1 loopback addresses in master.cf, + specify "inet_interfaces = loopback-only" in main.cf. This way you can use + the same master.cf file regardless of whether or not Postfix will run on an + IPv6-enabled system. + + * The first new parameter is called inet_protocols. This specifies what + protocols Postfix will use when it makes or accepts network connections, + and also controls what DNS lookups Postfix will use when it makes network + connections. + + /etc/postfix/main.cf: + # You must stop/start Postfix after changing this parameter. + inet_protocols = ipv4 (DEFAULT: enable IPv4 only) + inet_protocols = all (enable IPv4, and IPv6 if supported) + inet_protocols = ipv4, ipv6 (enable both IPv4 and IPv6) + inet_protocols = ipv6 (enable IPv6 only) + + By default, Postfix uses IPv4 only, because most systems aren't attached to + an IPv6 network. + + o On systems with combined IPv4/IPv6 stacks, attempts to deliver mail via + IPv6 would always fail with "network unreachable", and those attempts + would only slow down Postfix. + + o Linux kernels don't even load IPv6 protocol support by default. Any + attempt to use it would fail immediately. + + Note 1: you must stop and start Postfix after changing the inet_protocols + configuration parameter. + + Note 2: if you see error messages like the following, then you're running + Linux and need to turn on IPv6 in the kernel: see http://www.ipv6.org/ for + hints and tips. Unlike other systems, Linux does not have a combined stack + for IPv4 and IPv6, and IPv6 protocol support is not loaded by default. + + postconf: warning: inet_protocols: IPv6 support is disabled: Address + family not supported by protocol + postconf: warning: inet_protocols: configuring for IPv4 support only + + Note 3: on older Linux and Solaris systems, the setting "inet_protocols = + ipv6" will not prevent Postfix from accepting IPv4 connections. Postfix + will present the client IP addresses in IPv6 format, though. In all other + cases, Postfix always presents IPv4 client IP addresses in the traditional + dotted quad IPv4 format. + + * The other new parameter is smtp_bind_address6. This sets the local + interface address for outgoing IPv6 SMTP connections, just like the + smtp_bind_address parameter does for IPv4: + + /etc/postfix/main.cf: + smtp_bind_address6 = 2001:240:587:0:250:56ff:fe89:1 + + * If you left the value of the mynetworks parameter at its default (i.e. no + mynetworks setting in main.cf) Postfix will figure out by itself what its + network addresses are. This is what a typical setting looks like: + + % postconf mynetworks + mynetworks = 127.0.0.0/8 168.100.189.0/28 [::1]/128 [fe80::]/10 [2001: + 240:587::]/64 + + If you did specify the mynetworks parameter value in main.cf, you need + update the mynetworks value to include the IPv6 networks the system is in. + Be sure to specify IPv6 address information inside "[]", like this: + + /etc/postfix/main.cf: + mynetworks = ...IPv4 networks... [::1]/128 [2001:240:587::]/64 ... + +NNOOTTEE:: wwhheenn ccoonnffiigguurriinngg PPoossttffiixx mmaattcchh lliissttss ssuucchh aass mmyynneettwwoorrkkss oorr +ddeebbuugg__ppeeeerr__lliisstt,, yyoouu mmuusstt ssppeecciiffyy IIPPvv66 aaddddrreessss iinnffoorrmmaattiioonn iinnssiiddee ""[[]]"" iinn tthhee +mmaaiinn..ccff ppaarraammeetteerr vvaalluuee aanndd iinn ffiilleess ssppeecciiffiieedd wwiitthh aa ""//ffiillee//nnaammee"" ppaatttteerrnn.. +IIPPvv66 aaddddrreesssseess ccoonnttaaiinn tthhee ""::"" cchhaarraacctteerr,, aanndd wwoouulldd ootthheerrwwiissee bbee ccoonnffuusseedd wwiitthh +aa ""ttyyppee::ttaabbllee"" ppaatttteerrnn.. + +KKnnoowwnn LLiimmiittaattiioonnss + + * Postfix SMTP clients before version 2.8 try to connect over IPv6 before + trying IPv4. With more recent Postfix versions, the order of IPv6 versus + IPv4 outgoing connection attempts is configurable with the + smtp_address_preference parameter. + + * Postfix versions before 2.6 do not support DNSBL (real-time blackhole list) + lookups for IPv6 client IP addresses. + + * IPv6 does not have class A, B, C, etc. networks. With IPv6 networks, the + setting "mynetworks_style = class" has the same effect as the setting + "mynetworks_style = subnet". + + * On Tru64Unix and AIX, Postfix can't figure out the local subnet mask and + always assumes a /128 network. This is a problem only with + "mynetworks_style = subnet" and no explicit mynetworks setting in main.cf. + +CCoommppaattiibbiilliittyy wwiitthh PPoossttffiixx <<22..22 IIPPvv66 ssuuppppoorrtt + +Postfix version 2.2 IPv6 support is based on the Postfix/IPv6 patch by Dean +Strik and others, but differs in a few minor ways. + + * main.cf: The inet_interfaces parameter does not support the notation "ipv6: + all" or "ipv4:all". Use the inet_protocols parameter instead. + + * main.cf: Specify "inet_protocols = all" or "inet_protocols = ipv4, ipv6" in + order to enable both IPv4 and IPv6 support. + + * main.cf: The inet_protocols parameter also controls what DNS lookups + Postfix will attempt to make when delivering or receiving mail. + + * main.cf: Specify "inet_interfaces = loopback-only" to listen on loopback + network interfaces only. + + * The lmtp_bind_address and lmtp_bind_address6 features were omitted. The + Postfix LMTP client will be absorbed into the SMTP client, so there is no + reason to keep adding features to the LMTP client. + + * The SMTP server now requires that IPv6 addresses in SMTP commands are + specified as [ipv6:ipv6address], as described in RFC 2821. + + * The IPv6 network address matching code was rewritten from the ground up, + and is expected to be closer to the specification. The result may be + incompatible with the Postfix/IPv6 patch. + +IIPPvv66 SSuuppppoorrtt ffoorr uunnssuuppppoorrtteedd ppllaattffoorrmmss + +Getting Postfix IPv6 working on other platforms involves the following steps: + + * Specify how Postfix should find the local network interfaces. Postfix needs + this information to avoid mailer loops and to find out if mail for user@ + [ipaddress] is a local or remote destination. + + If your system has the getifaddrs() routine then add the following to your + platform-specific section in src/util/sys_defs.h: + + #ifndef NO_IPV6 + # define HAS_IPV6 + # define HAVE_GETIFADDRS + #endif + + Otherwise, if your system has the SIOCGLIF ioctl() command in /usr/include/ + */*.h, add the following to your platform-specific section in src/util/ + sys_defs.h: + + #ifndef NO_IPV6 + # define HAS_IPV6 + # define HAS_SIOCGLIF + #endif + + Otherwise, Postfix will have to use the old SIOCGIF commands and get along + with reduced IPv6 functionality (it won't be able to figure out your IPv6 + netmasks, which are needed for "mynetworks_style = subnet". Add this to + your platform-specific section in src/util/sys_defs.h: + + #ifndef NO_IPV6 + # define HAS_IPV6 + #endif + + * Test if Postfix can figure out its interface information. + + After compiling Postfix in the usual manner, step into the src/util + directory and type "mmaakkee iinneett__aaddddrr__llooccaall". Running this file by hand should + produce all the interface addresses and network masks, for example: + + % make + % cd src/util + % make inet_addr_local + [... some messages ...] + % ./inet_addr_local + [... some messages ...] + ./inet_addr_local: inet_addr_local: configured 2 IPv4 addresses + ./inet_addr_local: inet_addr_local: configured 4 IPv6 addresses + 168.100.189.2/255.255.255.224 + 127.0.0.1/255.0.0.0 + fe80:1::2d0:b7ff:fe88:2ca7/ffff:ffff:ffff:ffff:: + 2001:240:587:0:2d0:b7ff:fe88:2ca7/ffff:ffff:ffff:ffff:: + fe80:5::1/ffff:ffff:ffff:ffff:: + ::1/ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff + + The above is for an old FreeBSD machine. Other systems produce slightly + different results, but you get the idea. + +If none of all this produces a usable result, send email to the postfix- +users@postfix.org mailing list and we'll try to help you through this. + +CCrreeddiittss + +The following information is in part based on information that was compiled by +Dean Strik. + + * Mark Huizer wrote the original Postfix IPv6 patch. + + * Jun-ichiro 'itojun' Hagino of the KAME project made substantial + improvements. Since then, we speak of the KAME patch. + + * The PLD Linux Distribution ported the code to other stacks (notably USAGI). + We speak of the PLD patch. A very important feature of the PLD patch was + that it can work with Lutz Jaenicke's TLS patch for Postfix. + + * Dean Strik extended IPv6 support to platforms other than KAME and USAGI, + updated the patch to keep up with Postfix development, and provided a + combined IPv6 + TLS patch. Information about his effort can be found on + Dean Strik's Postfix website at http://www.ipnet6.org/postfix/. + + * Wietse Venema took Dean Strik's IPv6 patch, merged it into Postfix 2.2, and + took the opportunity to eliminate all IPv4-specific code from Postfix that + could be removed. For systems without IPv6 support in the kernel and system + libraries, Postfix has a simple compatibility layer, so that it will use + IPv4 as before. + |