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.\" 4.\" Copyright (c) 1986, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.Dd November 1, 2018 32.Dt ICMP6 4 33.Os 34.Sh NAME 35.Nm icmp6 36.Nd Internet Control Message Protocol for IPv6 37.Sh SYNOPSIS 38.In sys/socket.h 39.In netinet/in.h 40.In netinet/icmp6.h 41.Ft int 42.Fn socket AF_INET6 SOCK_RAW IPPROTO_ICMPV6 43.Sh DESCRIPTION 44ICMPv6 is the error and control message protocol used by IPv6 and the 45IPv6 protocol family (see 46.Xr ip6 4 47and 48.Xr inet6 4 ) . 49It may be accessed through a 50.Dq raw socket 51for network monitoring and diagnostic functions. 52.Pp 53The 54.Fa proto 55parameter to the 56.Xr socket 2 57call to create an ICMPv6 socket may be obtained from 58.Xr getprotobyname 3 . 59ICMPv6 sockets are connectionless, and are normally used with the 60.Xr sendto 2 61and 62.Xr recvfrom 2 63calls, though the 64.Xr connect 2 65call may also be used to fix the destination for future packets 66(in which case 67.Xr read 2 68or 69.Xr recv 2 70and 71.Xr write 2 72or 73.Xr send 2 74system calls may be used). 75.Pp 76Outgoing packets automatically have an IPv6 header prepended to them 77(based on the destination address). 78Incoming packets on the socket are received with the IPv6 header and any 79extension headers removed. 80.Ss Types 81ICMPv6 messages are classified according to the type and code fields 82present in the ICMPv6 header. 83The abbreviations for the types and codes may be used in rules in 84.Xr pf.conf 5 . 85The following types are defined: 86.Bl -column x xxxxxxxxxxxx -offset indent 87.It Sy Num Ta Sy Abbrev. Ta Sy Description 88.It 1 Ta unreach Ta "Destination unreachable" 89.It 2 Ta toobig Ta "Packet too big" 90.It 3 Ta timex Ta "Time exceeded" 91.It 4 Ta paramprob Ta "Invalid IPv6 header" 92.It 128 Ta echoreq Ta "Echo service request" 93.It 129 Ta echorep Ta "Echo service reply" 94.It 130 Ta groupqry Ta "Group membership query" 95.It 130 Ta listqry Ta "Multicast listener query" 96.It 131 Ta grouprep Ta "Group membership report" 97.It 131 Ta listenrep Ta "Multicast listener report" 98.It 132 Ta groupterm Ta "Group membership termination" 99.It 132 Ta listendone Ta "Multicast listener done" 100.It 133 Ta routersol Ta "Router solicitation" 101.It 134 Ta routeradv Ta "Router advertisement" 102.It 135 Ta neighbrsol Ta "Neighbor solicitation" 103.It 136 Ta neighbradv Ta "Neighbor advertisement" 104.It 137 Ta redir Ta "Shorter route exists" 105.It 138 Ta routrrenum Ta "Route renumbering" 106.It 139 Ta fqdnreq Ta "FQDN query" 107.It 139 Ta niqry Ta "Node information query" 108.It 139 Ta wrureq Ta "Who-are-you request" 109.It 140 Ta fqdnrep Ta "FQDN reply" 110.It 140 Ta nirep Ta "Node information reply" 111.It 140 Ta wrurep Ta "Who-are-you reply" 112.It 200 Ta mtraceresp Ta "mtrace response" 113.It 201 Ta mtrace Ta "mtrace messages" 114.El 115.Pp 116The following codes are defined: 117.Bl -column x xxxxxxxxxxxx xxxxxxxx -offset indent 118.It Sy Num Ta Sy Abbrev. Ta Sy Type Ta 119.Sy Description 120.It 0 Ta noroute-unr Ta unreach Ta "No route to destination" 121.It 1 Ta admin-unr Ta unreach Ta "Administratively prohibited" 122.It 2 Ta beyond-unr Ta unreach Ta "Beyond scope of source address" 123.It 2 Ta notnbr-unr Ta unreach Ta "Not a neighbor (obsolete)" 124.It 3 Ta addr-unr Ta unreach Ta "Address unreachable" 125.It 4 Ta port-unr Ta unreach Ta "Port unreachable" 126.It 0 Ta transit Ta timex Ta "Time exceeded in transit" 127.It 1 Ta reassemb Ta timex Ta "Time exceeded in reassembly" 128.It 0 Ta badhead Ta paramprob Ta "Erroneous header field" 129.It 1 Ta nxthdr Ta paramprob Ta "Unrecognized next header" 130.It 2 Ta "" Ta redir Ta "Unrecognized option" 131.It 0 Ta redironlink Ta redir Ta "Redirection to on-link node" 132.It 1 Ta redirrouter Ta redir Ta "Redirection to better router" 133.El 134.Ss Headers 135All ICMPv6 messages are prefixed with an ICMPv6 header. 136This header corresponds to the 137.Vt icmp6_hdr 138structure and has the following definition: 139.Bd -literal -offset indent 140struct icmp6_hdr { 141 uint8_t icmp6_type; /* type field */ 142 uint8_t icmp6_code; /* code field */ 143 uint16_t icmp6_cksum; /* checksum field */ 144 union { 145 uint32_t icmp6_un_data32[1]; /* type-specific */ 146 uint16_t icmp6_un_data16[2]; /* type-specific */ 147 uint8_t icmp6_un_data8[4]; /* type-specific */ 148 } icmp6_dataun; 149} __packed; 150 151#define icmp6_data32 icmp6_dataun.icmp6_un_data32 152#define icmp6_data16 icmp6_dataun.icmp6_un_data16 153#define icmp6_data8 icmp6_dataun.icmp6_un_data8 154#define icmp6_pptr icmp6_data32[0] /* parameter prob */ 155#define icmp6_mtu icmp6_data32[0] /* packet too big */ 156#define icmp6_id icmp6_data16[0] /* echo request/reply */ 157#define icmp6_seq icmp6_data16[1] /* echo request/reply */ 158#define icmp6_maxdelay icmp6_data16[0] /* mcast group membership*/ 159.Ed 160.Pp 161.Va icmp6_type 162describes the type of the message. 163Suitable values are defined in 164.Aq Pa netinet/icmp6.h . 165.Va icmp6_code 166describes the sub-type of the message and depends on 167.Va icmp6_type . 168.Va icmp6_cksum 169contains the checksum for the message and is filled in by the 170kernel on outgoing messages. 171The other fields are used for type-specific purposes. 172.Ss Filters 173Because of the extra functionality of ICMPv6 in comparison to ICMPv4, 174a larger number of messages may be potentially received on an ICMPv6 175socket. 176Input filters may therefore be used to restrict input to a subset of the 177incoming ICMPv6 messages so only interesting messages are returned by the 178.Xr recv 2 179family of calls to an application. 180.Pp 181The 182.Vt icmp6_filter 183structure may be used to refine the input message set according to the 184ICMPv6 type. 185By default, all messages types are allowed on newly created raw ICMPv6 186sockets. 187The following macros may be used to refine the input set: 188.Bl -tag -width Ds 189.It Ft void Fn ICMP6_FILTER_SETPASSALL "struct icmp6_filter *filterp" 190Allow all incoming messages. 191.Va filterp 192is modified to allow all message types. 193.It Ft void Fn ICMP6_FILTER_SETBLOCKALL "struct icmp6_filter *filterp" 194Ignore all incoming messages. 195.Va filterp 196is modified to ignore all message types. 197.It Xo 198.Ft void 199.Fn ICMP6_FILTER_SETPASS "int type" "struct icmp6_filter *filterp" 200.Xc 201Allow ICMPv6 messages with the given 202.Fa type . 203.Va filterp 204is modified to allow such messages. 205.It Xo 206.Ft void 207.Fn ICMP6_FILTER_SETBLOCK "int type" "struct icmp6_filter *filterp" 208.Xc 209Ignore ICMPv6 messages with the given 210.Fa type . 211.Va filterp 212is modified to ignore such messages. 213.It Xo 214.Ft int 215.Fn ICMP6_FILTER_WILLPASS "int type" "const struct icmp6_filter *filterp" 216.Xc 217Determine if the given filter will allow an ICMPv6 message of the given 218type. 219.It Xo 220.Ft int 221.Fn ICMP6_FILTER_WILLBLOCK "int type" "const struct icmp6_filter *filterp" 222.Xc 223Determine if the given filter will ignore an ICMPv6 message of the given 224type. 225.El 226.Pp 227The 228.Xr getsockopt 2 229and 230.Xr setsockopt 2 231calls may be used to obtain and install the filter on ICMPv6 sockets at 232option level 233.Dv IPPROTO_ICMPV6 234and name 235.Dv ICMP6_FILTER 236with a pointer to the 237.Vt icmp6_filter 238structure as the option value. 239.Sh SEE ALSO 240.Xr getsockopt 2 , 241.Xr recv 2 , 242.Xr send 2 , 243.Xr setsockopt 2 , 244.Xr socket 2 , 245.Xr getprotobyname 3 , 246.Xr inet6 4 , 247.Xr ip6 4 , 248.Xr netintro 4 249.Rs 250.%A W. Stevens 251.%A M. Thomas 252.%T Advanced Sockets API for IPv6 253.%N RFC 2292 254.%D February 1998 255.Re 256.Rs 257.%A A. Conta 258.%A S. Deering 259.%T "Internet Control Message Protocol (ICMPv6) for the Internet" \ 260 "Protocol Version 6 (IPv6) Specification" 261.%N RFC 2463 262.%D December 1998 263.Re 264.Rs 265.%A W. Stevens 266.%A M. Thomas 267.%A E. Nordmark 268.%A T. Jinmei 269.%T "Advanced Sockets Application Program Interface (API) for IPv6" 270.%R RFC 3542 271.%D May 2003 272.Re 273.Rs 274.%A A. Conta 275.%A S. Deering 276.%A M. Gupta 277.%T "Internet Control Message Protocol (ICMPv6) for the Internet" \ 278 "Protocol Version 6 (IPv6) Specification" 279.%R RFC 4443 280.%D March 2006 281.Re 282