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1 perry 1 IPV6
2 !!!IPV6
3 NAME
4 SYNOPSIS
5 DESCRIPTION
6 ADDRESS FORMAT
7 SOCKET OPTIONS
8 VERSIONS
9 PORTING NOTES
10 BUGS
11 SEE ALSO
12 ----
13 !!NAME
14
15
16 ipv6, PF_INET6 - Linux IPv6 protocol implementation
17 !!SYNOPSIS
18
19
20 __#include __
21 #include __
22
23
24 ''tcp6_socket'' __= socket(PF_INET6, SOCK_STREAM,
25 0);__''
26 raw6_socket'' __= socket(PF_INET6, SOCK_RAW,__
27 ''protocol''__);__''
28 udp6_socket'' __= socket(PF_INET6, SOCK_DGRAM,__
29 ''protocol''__);__
30 !!DESCRIPTION
31
32
33 Linux 2.2 optionally implements the Internet Protocol,
34 version 6. This man page contains a description of the IPv6
35 basic API as implemented by the Linux kernel and glibc 2.1.
36 The interface is based on the BSD sockets interface; see
37 socket(7).
38
39
40 The IPv6 API aims to be mostly compatible with the
41 ip(7) v4 API. Only differences are described in this
42 man page.
43
44
45 To bind an ''AF_INET6'' socket to any process the local
46 address should be copied from the __in6addr_any__
47 variable which has ''in6_addr'' type. In static
48 initializations __IN6ADDR_ANY_INIT__ may also be used,
49 which expands to a constant expression. Both of them are in
50 network order.
51
52
53 The IPv6 loopback address (::1) is available in the global
54 __in6addr_loopback__ variable. For initializations
55 __IN6ADDR_LOOPBACK_INIT__ should be used.
56
57
58 IPv4 connections can be handled with the v6 API by using the
59 v4-mapped-on-v6 address type; thus a program only needs only
60 to support this API type to support both protocols. This is
61 handled transparently by the address handling functions in
62 libc.
63
64
65 IPv4 and IPv6 share the local port space. When you get an
66 IPv4 connection or packet to a IPv6 socket its source
67 address will be mapped to v6 and it'll be mapped to
68 v6.
69 !!ADDRESS FORMAT
70
71
72 struct sockaddr_in6 {
73 u_int16_t sin6_family;/* AF_INET6 */
74 u_int16_t sin6_port;/* port number */
75 u_int32_t sin6_flowinfo;/* IPv6 flow information */
76 struct in6_addr sin6_addr;/* IPv6 address */
77 u_int32_t sin6_scope_id; /* Scope id (new in 2.4) */
78 };
79 struct in6_addr {
80 unsigned char s6_addr[[16];/* IPv6 address */
81 };
82
83
84 __sin6_family__ is always set to __AF_INET6;
85 sin6_port__ is the protocol port (see __sin_port__ in
86 ip(7)); __sin6_flowinfo__ is the IPv6 flow
87 identifier; __sin6_addr__ is the 128bit IPv6 address.
88 __sin6_scope_id__ is an id of depending of on the scope
89 of the address. It is new in Linux 2.4. Linux only supports
90 it for link scope addresses, in that case
91 ''sin6_scope_id'' contains the interface index (see
92 netdevice(7))
93
94
95 IPv6 supports several address types: unicast to address a
96 single host, multicast to address a group of hosts, anycast
97 to address the nearest member of a group of hosts (not
98 implemented in Linux), IPv4-on-IPv6 to address a IPv4 host,
99 and other reserved address types.
100
101
102 The address notation for IPv6 is a group of 16 2 digit
103 hexadecimal numbers, separated with a ':'. '::' stands for a
104 string of 0 bits. Special addresses are ::1 for loopback and
105 FFFF::
106
107
108 The port space of IPv6 is shared with IPv4.
109 !!SOCKET OPTIONS
110
111
112 IPv6 supports some protocol specific socket options that can
113 be set with setsockopt(2) and read with
114 getsockopt(2). The socket option level for IPv6 is
115 __IPPROTO_IPV6__. A boolean integer flag is zero when it
116 is false, otherwise true.
117
118
119 __IPV6_UNICAST_HOPS__
120
121
122 Set the unicast hop limit for the socket. Argument is an
123 pointer to an integer. -1 in the value means use the route
124 default, otherwise it should be between 0 and
125 255.
126
127
128 __IPV6_MULTICAST_HOPS__
129
130
131 Set the multicast hop limit for the socket. Argument is a
132 pointer to an integer. -1 in the value means use the route
133 default, otherwise it should be between 0 and
134 255.
135
136
137 __IPV6_MULTICAST_IF__
138
139
140 Set the device for outgoing multicast packets on the socket.
141 This is only allowed for ''SOCK_DGRAM'' and
142 ''SOCK_RAW'' socket. The argument is an pointer to an
143 interface index (see netdevice(7)) in an
144 integer.
145
146
147 __IPV6_ADDRFORM__
148
149
150 Turn an ''AF_INET6'' socket into a socket of a different
151 address family. Only ''AF_INET'' is currently supported
152 for that. It is only allowed for IPv6 sockets that are
153 connected and bound to a v4-mapped-on-v6 address. The
154 argument is a pointer to a integer containing
155 __AF_INET.__ This is useful to pass v4-mapped sockets as
156 filedescriptors to programs that don't know how to deal with
157 the IPv6 API.
158
159
160 __IPV6_PKTINFO__
161
162
163 Set delivery of the __IPV6_PKTINFO__ control message on
164 incoming datagrams. Only allowed for __SOCK_DGRAM__ or
165 __SOCK_RAW__ sockets. Argument is a pointer to a boolean
166 value in an integer.
167
168
169 __IPV6_RTHDR, IPV6_AUTHHDR, IPV6_DSTOPS, IPV6_HOPOPTS,
170 IPV6_FLOWINFO, IPV6_HOPLIMIT__
171
172
173 Set delivery of control messages for incoming data- grams
174 containing extension headers from the re- ceived packet.
175 ''IPV6_RTHDR'' delivers the routing header,
176 ''IPV6_AUTHHDR'' delivers the authentication header,
177 ''IPV6_DSTOPTS'' delivers the destination op- tions,
178 ''IPV6_HOPOPTS'' delivers the hop options,
179 ''IPV6_FLOWINFO'' delivers an integer containing the flow
180 id, ''IPV6_HOPLIMIT'' delivers an integer contain- ing
181 the hop count of the packet. The control mes- sages have the
182 same type as the socket option. All these header options can
183 also be set for outgoing packets by putting the appropriate
184 control message into the control buffer of
185 sendmsg(2). Only al- lowed for __SOCK_DGRAM__ or
186 __SOCK_RAW__ sockets. Argument is a pointer to a boolean
187 value.
188
189
190 __IPV6_MULTICAST_LOOP__
191
192
193 Control whether the socket sees multicast packets that is
194 has send itself. Argument is a pointer to
195 boolean.
196
197
198 __IPV6_ADD_MEMBERSHIP,
199 IPV6_DROP_MEMBERSHIP__
200
201
202 Control membership in multicast groups. Argument is a
203 pointer to a __struct ipv6_mreq__ structure.
204
205
206 __IPV6_MTU__
207
208
209 Set the MTU to be used for the socket. The MTU is limited by
210 the device MTU or the path mtu when path mtu discovery is
211 enabled. Argument is a pointer to integer.
212
213
214 __IPV6_MTU_DISCOVER__
215
216
217 Control path mtu discovery on the socket. See
218 ''IP_MTU_DISCOVER'' in ip(7) for
219 details.
220
221
222 __IPV6_RECVERR__
223
224
225 Control receiving of asynchronous error options. See
226 ''IP_RECVERR'' in ip(7) for details. Argument is a
227 pointer to boolean.
228
229
230 __IPV6_ROUTER_ALERT__
231
232
233 Pass all forwarded packets containing an router alert option
234 to this socket. Only allowed for datagram sockets and for
235 root. Argument is a point- er to boolean.
236 !!VERSIONS
237
238
239 The older ''libinet6'' libc5 based IPv6 API
240 implementation for Linux is not described here and may vary
241 in details.
242
243
244 Linux 2.4 will break binary compatibility for the sockad-
245 dr_in6 for 64bit hosts by changing the alignment of
246 ''in6_addr'' and adding an additional
247 ''sin6_scope_id'' field. The kernel interfaces stay
248 compatible, but a program including sockaddr_in6 or in6_addr
249 into other structures may not be. This is not a problem for
250 32bit hosts like i386.
251
252
253 The __sin6_flowinfo__ field is new in Linux 2.4. It is
254 trans- parently passed/read by the kernel when the passed
255 address length contains it. Some programs that pass a longer
256 ad- dress buffer and then check the outgoing address length
257 may break.
258 !!PORTING NOTES
259
260
261 The __sockaddr_in6__ structure is bigger than the generic
262 __sockaddr.__ Programs that assume that all address types
263 can be stored safely in a __struct sockaddr__ need to be
264 changed to use __struct sockaddr_storage__ for that
265 instead.
266 !!BUGS
267
268
269 The IPv6 extended API as in RFC2292 is currently only partly
270 implemented; although the 2.2 kernel has near com- plete
271 support for receiving options, the macros for gener- ating
272 IPv6 options are missing in glibc 2.1.
273
274
275 IPSec support for EH and AH headers is missing.
276
277
278 Flow label management is not complete and not documented
279 here.
280
281
282 This man page is not complete.
283 !!SEE ALSO
284
285
286 ip(7), cmsg(3)
287
288
289 RFC2553: IPv6 BASIC API. Linux tries to be compliant to
290 this.
291
292
293 RFC2460: IPv6 specification.
294 ----
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