1.\" Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the project nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" $Id: inet6.4,v 1.1.1.1 1999/08/08 23:30:37 itojun Exp $ 29.\" $FreeBSD$ 30.\" 31.Dd January 29, 1999 32.Dt INET6 4 33.Os 34.Sh NAME 35.Nm inet6 36.Nd Internet protocol version 6 family 37.Sh SYNOPSIS 38.Fd #include <sys/types.h> 39.Fd #include <netinet/in.h> 40.Sh DESCRIPTION 41The 42.Nm 43family is an updated version of 44.Xr inet 4 45family. 46While 47.Xr inet 4 48implements Internet Protocol version 4, 49.Nm 50implements Internet Protocol version 6. 51.Pp 52.Nm 53is a collection of protocols layered atop the 54.Em Internet Protocol version 6 55.Pq Tn IPv6 56transport layer, and utilizing the IPv6 address format. 57The 58.Nm 59family provides protocol support for the 60.Dv SOCK_STREAM , SOCK_DGRAM , 61and 62.Dv SOCK_RAW 63socket types; the 64.Dv SOCK_RAW 65interface provides access to the 66.Tn IPv6 67protocol. 68.Sh ADDRESSING 69IPv6 addresses are 16 byte quantities, stored in network standard format 70The include file 71.Aq Pa netinet/in.h 72defines this address 73as a discriminated union. 74.Pp 75Sockets bound to the 76.Nm 77family utilize the following addressing structure, 78.Bd -literal -offset indent 79struct sockaddr_in6 { 80 u_char sin6_len; 81 u_char sin6_family; 82 u_int16_t sin6_port; 83 u_int32_t sin6_flowinfo; 84 struct in6_addr sin6_addr; 85 u_int32_t sin6_scope_id; 86}; 87.Ed 88.Pp 89Sockets may be created with the local address 90.Dq Dv :: 91.Po 92which is equal to IPv6 address 93.Dv 0:0:0:0:0:0:0:0 94.Pc 95to effect 96.Dq wildcard 97matching on incoming messages. 98The address in a 99.Xr connect 2 100or 101.Xr sendto 2 102call may be given as 103.Dq Dv :: 104to mean 105.Dq this host . 106.Dq Dv :: 107can be obtained by setting 108.Dv sin6_addr 109field into 0, or by using the address contained in variable 110.Dv in6addr_any . 111.Pp 112IPv6 defines scoped address such as link-local or site-local address. 113To manipulate link-local addresses properly from the userland, 114programs must use advanced API defined in RFC2292. 115Otherwise, the address is ambiguous to the kernel and error will be generated. 116Scoped address is not for daily use at this moment both from specification 117and implementation point of view. 118Most of normal userland program 119like 120.Xr telnet 1 121or 122.Xr telnetd 8 123cannot handle scoped address properly. 124Only special programs, 125like 126.Xr ping6 8 , 127supports scoped address. 128For example, 129.Xr ping6 8 130has special option for specifying outgoing interface 131to disambiguate scoped addresses. 132.Pp 133Scoped addresses are handled specially in the kernel. 134Scoped addresses will have its interface index embedded into the address, 135in routing table or interface structure. 136Therefore, 137the address on some of the kernel structure is not the same as that on the wire. 138The embedded index will be visible on 139.Dv PF_ROUTE 140socket and results from 141.Xr ifconfig 8 , 142HOWEVER, users should never use the embedded form. 143For details please consult 144.Pa IMPLEMENTATION 145supplied with KAME kit. 146.Sh PROTOCOLS 147The 148.Nm 149family is comprised of the 150.Tn IPv6 151network protocol, Internet Control 152Message Protocol version 6 153.Pq Tn ICMPv6 , 154Transmission Control Protocol 155.Pq Tn TCP , 156and User Datagram Protocol 157.Pq Tn UDP . 158.Tn TCP 159is used to support the 160.Dv SOCK_STREAM 161abstraction while 162.Tn UDP 163is used to support the 164.Dv SOCK_DGRAM 165abstraction. 166Note that 167.Tn TCP 168and 169.Tn UDP 170are common to 171.Xr inet 4 172and 173.Nm inet6 . 174A raw interface to 175.Tn IPv6 176is available 177by creating an Internet socket of type 178.Dv SOCK_RAW . 179The 180.Tn ICMPv6 181message protocol is accessible from a raw socket. 182.\" .Pp 183.\" The 128-bit IPv6 address contains both network and host parts. 184.\" However, direct examination of addresses is discouraged. 185.\" For those programs which absolutely need to break addresses 186.\" into their component parts, the following 187.\" .Xr ioctl 2 188.\" commands are provided for a datagram socket in the 189.\" .Nm 190.\" domain; they have the same form as the 191.\" .Dv SIOCIFADDR 192.\" command (see 193.\" .Xr intro 4 ) . 194.\" .Pp 195.\" .Bl -tag -width SIOCSIFNETMASK 196.\" .It Dv SIOCSIFNETMASK 197.\" Set interface network mask. 198.\" The network mask defines the network part of the address; 199.\" if it contains more of the address than the address type would indicate, 200.\" then subnets are in use. 201.\" .It Dv SIOCGIFNETMASK 202.\" Get interface network mask. 203.\" .El 204.\" .Sh ROUTING 205.\" The current implementation of Internet protocols includes some routing-table 206.\" adaptations to provide enhanced caching of certain end-to-end 207.\" information necessary for Transaction TCP and Path MTU Discovery. The 208.\" following changes are the most significant: 209.\" .Bl -enum 210.\" .It 211.\" All IP routes, except those with the 212.\" .Dv RTF_CLONING 213.\" flag and those to multicast destinations, have the 214.\" .Dv RTF_PRCLONING 215.\" flag forcibly enabled (they are thus said to be 216.\" .Dq "protocol cloning" ). 217.\" .It 218.\" When the last reference to an IP route is dropped, the route is 219.\" examined to determine if it was created by cloning such a route. If 220.\" this is the case, the 221.\" .Dv RTF_PROTO3 222.\" flag is turned on, and the expiration timer is initialized to go off 223.\" in net.inet.ip.rtexpire seconds. If such a route is re-referenced, 224.\" the flag and expiration timer are reset. 225.\" .It 226.\" A kernel timeout runs once every ten minutes, or sooner if there are 227.\" soon-to-expire routes in the kernel routing table, and deletes the 228.\" expired routes. 229.\" .El 230.\" .Pp 231.\" A dynamic process is in place to modify the value of 232.\" net.inet.ip.rtexpire if the number of cached routes grows too large. 233.\" If after an expiration run there are still more than 234.\" net.inet.ip.rtmaxcache unreferenced routes remaining, the rtexpire 235.\" value is multiplied by 3/4, and any routes which have longer 236.\" expiration times have those times adjusted. This process is damped 237.\" somewhat by specification of a minimum rtexpire value 238.\" (net.inet.ip.rtminexpire), and by restricting the reduction to once in 239.\" a ten-minute period. 240.\" .Pp 241.\" If some external process deletes the original route from which a 242.\" protocol-cloned route was generated, the ``child route'' is deleted. 243.\" (This is actually a generic mechanism in the routing code support for 244.\" protocol-requested cloning.) 245.\" .Pp 246.\" No attempt is made to manage routes which were not created by protocol 247.\" cloning; these are assumed to be static, under the management of an 248.\" external routing process, or under the management of a link layer 249.\" (e.g., 250.\" .Tn ARP 251.\" for Ethernets). 252.\" .Pp 253.\" Only certain types of network activity will result in the cloning of a 254.\" route using this mechanism. Specifically, those protocols (such as 255.\" .Tn TCP 256.\" and 257.\" .Tn UDP ) 258.\" which themselves cache a long-lasting reference to route for a destination 259.\" will trigger the mechanism; whereas raw 260.\" .Tn IP 261.\" packets, whether locally-generated or forwarded, will not. 262.Sh SEE ALSO 263.Xr ioctl 2 , 264.Xr socket 2 , 265.Xr sysctl 3 , 266.Xr icmp6 4 , 267.Xr intro 4 , 268.\" .Xr ip6 4 , 269.Xr tcp 4 , 270.Xr ttcp 4 , 271.Xr udp 4 272.Sh CAVEAT 273The IPv6 support is subject to change as the Internet protocols develop. 274Users should not depend on details of the current implementation, 275but rather the services exported. 276.Pp 277Users are suggested to implement 278.Dq version independent 279code as much as possible, as you will need to support both 280.Xr inet 4 281and 282.Nm inet6 . 283.Sh HISTORY 284The 285.Nm 286protocol interface are defined in RFC2553 and RFC2292. 287The implementation described herein appeared in WIDE/KAME project. 288