1.\" $KAME: icmp6.4,v 1.6 2004/12/27 05:30:56 itojun Exp $ 2.\" $OpenBSD: icmp6.4,v 1.19 2004/12/23 20:33:03 jaredy Exp $ 3.\" $FreeBSD: src/share/man/man4/icmp6.4,v 1.16 2005/01/23 16:02:48 gnn Exp $ 4.\" $DragonFly: src/share/man/man4/icmp6.4,v 1.6 2007/11/23 23:03:57 swildner Exp $ 5.\" 6.\" Copyright (c) 1986, 1991, 1993 7.\" The Regents of the University of California. All rights reserved. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. Neither the name of the University nor the names of its contributors 18.\" may be used to endorse or promote products derived from this software 19.\" without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.Dd December 20, 2004 33.Dt ICMP6 4 34.Os 35.Sh NAME 36.Nm icmp6 37.Nd Internet Control Message Protocol for IPv6 38.Sh SYNOPSIS 39.In sys/socket.h 40.In netinet/in.h 41.In netinet/icmp6.h 42.Ft int 43.Fn socket AF_INET6 SOCK_RAW IPPROTO_ICMPV6 44.Sh DESCRIPTION 45ICMPv6 is the error and control message protocol used by IPv6 and the 46IPv6 protocol family (see 47.Xr ip6 4 48and 49.Xr inet6 4 ) . 50It may be accessed through a 51.Dq raw socket 52for network monitoring and diagnostic functions. 53.Pp 54The 55.Fa proto 56parameter to the 57.Xr socket 2 58call to create an ICMPv6 socket may be obtained from 59.Xr getprotobyname 3 . 60ICMPv6 sockets are connectionless, and are normally used with the 61.Xr sendto 2 62and 63.Xr recvfrom 2 64calls, though the 65.Xr connect 2 66call may also be used to fix the destination for future packets 67(in which case 68.Xr read 2 69or 70.Xr recv 2 71and 72.Xr write 2 73or 74.Xr send 2 75system calls may be used). 76.Pp 77Outgoing packets automatically have an IPv6 header prepended to them 78(based on the destination address). 79Incoming packets on the socket are received with the IPv6 header and any 80extension headers removed. 81.Ss Types 82ICMPv6 messages are classified according to the type and code fields 83present in the ICMPv6 header. 84The abbreviations for the types and codes may be used in rules in 85.Xr pf.conf 5 . 86The following types are defined: 87.Bl -column x xxxxxxxxxxxx -offset indent 88.It Sy Num Ta Sy Abbrev. Ta Sy Description 89.It 1 Ta unreach Ta "Destination unreachable" 90.It 2 Ta toobig Ta "Packet too big" 91.It 3 Ta timex Ta "Time exceeded" 92.It 4 Ta paramprob Ta "Invalid IPv6 header" 93.It 128 Ta echoreq Ta "Echo service request" 94.It 129 Ta echorep Ta "Echo service reply" 95.It 130 Ta groupqry Ta "Group membership query" 96.It 130 Ta listqry Ta "Multicast listener query" 97.It 131 Ta grouprep Ta "Group membership report" 98.It 131 Ta listenrep Ta "Multicast listener report" 99.It 132 Ta groupterm Ta "Group membership termination" 100.It 132 Ta listendone Ta "Multicast listerner done" 101.It 133 Ta routersol Ta "Router solicitation" 102.It 134 Ta routeradv Ta "Router advertisement" 103.It 135 Ta neighbrsol Ta "Neighbor solicitation" 104.It 136 Ta neighbradv Ta "Neighbor advertisement" 105.It 137 Ta redir Ta "Shorter route exists" 106.It 138 Ta routrrenum Ta "Route renumbering" 107.It 139 Ta fqdnreq Ta "FQDN query" 108.It 139 Ta niqry Ta "Node information query" 109.It 139 Ta wrureq Ta "Who-are-you request" 110.It 140 Ta fqdnrep Ta "FQDN reply" 111.It 140 Ta nirep Ta "Node information reply" 112.It 140 Ta wrurep Ta "Who-are-you reply" 113.It 200 Ta mtraceresp Ta "mtrace response" 114.It 201 Ta mtrace Ta "mtrace messages" 115.El 116.Pp 117The following codes are defined: 118.Bl -column x xxxxxxxxxxxx xxxxxxxx -offset indent 119.It Sy Num Ta Sy Abbrev. Ta Sy Type Ta 120.Sy Description 121.It 0 Ta noroute-unr Ta unreach Ta "No route to destination" 122.It 1 Ta admin-unr Ta unreach Ta "Administratively prohibited" 123.It 2 Ta beyond-unr Ta unreach Ta "Beyond scope of source address" 124.It 2 Ta notnbr-unr Ta unreach Ta "Not a neighbor (obselete)" 125.It 3 Ta addr-unr Ta unreach Ta "Address unreachable" 126.It 4 Ta port-unr Ta unreach Ta "Port unreachable" 127.It 0 Ta transit Ta timex Ta "Time exceeded in transit" 128.It 1 Ta reassemb Ta timex Ta "Time exceeded in reassembly" 129.It 0 Ta badhead Ta paramprob Ta "Erroneous header field" 130.It 1 Ta nxthdr Ta paramprob Ta "Unrecognized next header" 131.It 2 Ta "" Ta redir Ta "Unrecognized option" 132.It 0 Ta redironlink Ta redir Ta "Redirection to on-link node" 133.It 1 Ta redirrouter Ta redir Ta "Redirection to better router" 134.El 135.Ss Headers 136All ICMPv6 messages are prefixed with an ICMPv6 header. 137This header corresponds to the 138.Vt icmp6_hdr 139structure and has the following definition: 140.Bd -literal -offset indent 141struct icmp6_hdr { 142 u_int8_t icmp6_type; /* type field */ 143 u_int8_t icmp6_code; /* code field */ 144 u_int16_t icmp6_cksum; /* checksum field */ 145 union { 146 u_int32_t icmp6_un_data32[1]; /* type-specific */ 147 u_int16_t icmp6_un_data16[2]; /* type-specific */ 148 u_int8_t icmp6_un_data8[4]; /* type-specific */ 149 } icmp6_dataun; 150} __packed; 151 152#define icmp6_data32 icmp6_dataun.icmp6_un_data32 153#define icmp6_data16 icmp6_dataun.icmp6_un_data16 154#define icmp6_data8 icmp6_dataun.icmp6_un_data8 155#define icmp6_pptr icmp6_data32[0] /* parameter prob */ 156#define icmp6_mtu icmp6_data32[0] /* packet too big */ 157#define icmp6_id icmp6_data16[0] /* echo request/reply */ 158#define icmp6_seq icmp6_data16[1] /* echo request/reply */ 159#define icmp6_maxdelay icmp6_data16[0] /* mcast group membership*/ 160.Ed 161.Pp 162.Va icmp6_type 163describes the type of the message. 164Suitable values are defined in 165.In netinet/icmp6.h . 166.Va icmp6_code 167describes the sub-type of the message and depends on 168.Va icmp6_type . 169.Va icmp6_cksum 170contains the checksum for the message and is filled in by the 171kernel on outgoing messages. 172The other fields are used for type-specific purposes. 173.Ss Filters 174Because of the extra functionality of ICMPv6 in comparison to ICMPv4, 175a larger number of messages may be potentially received on an ICMPv6 176socket. 177Input filters may therefore be used to restrict input to a subset of the 178incoming ICMPv6 messages so only interesting messages are returned by the 179.Xr recv 2 180family of calls to an application. 181.Pp 182The 183.Vt icmp6_filter 184structure may be used to refine the input message set according to the 185ICMPv6 type. 186By default, all messages types are allowed on newly created raw ICMPv6 187sockets. 188The following macros may be used to refine the input set: 189.Bl -tag -width Ds 190.It Ft void Fn ICMP6_FILTER_SETPASSALL "struct icmp6_filter *filterp" 191Allow all incoming messages. 192.Va filterp 193is modified to allow all message types. 194.It Ft void Fn ICMP6_FILTER_SETBLOCKALL "struct icmp6_filter *filterp" 195Ignore all incoming messages. 196.Va filterp 197is modified to ignore all message types. 198.It Ft void Fn ICMP6_FILTER_SETPASS "int type" "struct icmp6_filter *filterp" 199Allow ICMPv6 messages with the given 200.Fa type . 201.Va filterp 202is modified to allow such messages. 203.It Ft void Fn ICMP6_FILTER_SETBLOCK "int type" "struct icmp6_filter *filterp" 204Ignore ICMPv6 messages with the given 205.Fa type . 206.Va filterp 207is modified to ignore such messages. 208.It Ft int Fn ICMP6_FILTER_WILLPASS "int type" \ 209 "const struct icmp6_filter *filterp" 210Determine if the given filter will allow an ICMPv6 message of the given 211type. 212.It Ft int Fn ICMP6_FILTER_WILLBLOCK "int type" \ 213 "const struct icmp6_filter *filterp" 214Determine if the given filter will ignore an ICMPv6 message of the given 215type. 216.El 217.Pp 218The 219.Xr getsockopt 2 220and 221.Xr setsockopt 2 222calls may be used to obtain and install the filter on ICMPv6 sockets at 223option level 224.Dv IPPROTO_ICMPV6 225and name 226.Dv ICMP6_FILTER 227with a pointer to the 228.Vt icmp6_filter 229structure as the option value. 230.Sh SEE ALSO 231.Xr getsockopt 2 , 232.Xr recv 2 , 233.Xr send 2 , 234.Xr setsockopt 2 , 235.Xr socket 2 , 236.Xr getprotobyname 3 , 237.Xr inet6 4 , 238.Xr ip6 4 , 239.Xr netintro 4 240.Rs 241.%A W. Stevens 242.%A M. Thomas 243.%T Advanced Sockets API for IPv6 244.%N RFC 2292 245.%D February 1998 246.Re 247.Rs 248.%A A. Conta 249.%A S. Deering 250.%T "Internet Control Message Protocol (ICMPv6) for the Internet" \ 251 "Protocol Version 6 (IPv6) Specification" 252.%N RFC 2463 253.%D December 1998 254.Re 255