266 lines
8.7 KiB
Groff
266 lines
8.7 KiB
Groff
.\" $KAME: icmp6.4,v 1.6 2004/12/27 05:30:56 itojun Exp $
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.\" $OpenBSD: icmp6.4,v 1.19 2004/12/23 20:33:03 jaredy Exp $
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.\"
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.\" Copyright (c) 1986, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 20, 2004
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.Dt ICMP6 4
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.Os
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.Sh NAME
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.Nm icmp6
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.Nd Internet Control Message Protocol for IPv6
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.Sh SYNOPSIS
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.In sys/socket.h
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.In netinet/in.h
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.In netinet/icmp6.h
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.Ft int
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.Fn socket AF_INET6 SOCK_RAW IPPROTO_ICMPV6
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.Sh DESCRIPTION
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ICMPv6 is the error and control message protocol used by IPv6 and the
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IPv6 protocol family (see
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.Xr ip6 4
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and
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.Xr inet6 4 ) .
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It may be accessed through a
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.Dq raw socket
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for network monitoring and diagnostic functions.
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.Pp
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The
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.Fa proto
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parameter to the
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.Xr socket 2
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call to create an ICMPv6 socket may be obtained from
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.Xr getprotobyname 3 .
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ICMPv6 sockets are connectionless, and are normally used with the
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.Xr sendto 2
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and
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.Xr recvfrom 2
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calls, though the
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.Xr connect 2
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call may also be used to fix the destination for future packets
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(in which case
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.Xr read 2
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or
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.Xr recv 2
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and
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.Xr write 2
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or
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.Xr send 2
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system calls may be used).
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.Pp
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Outgoing packets automatically have an IPv6 header prepended to them
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(based on the destination address).
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Incoming packets on the socket are received with the IPv6 header and any
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extension headers removed.
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.Ss Types
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ICMPv6 messages are classified according to the type and code fields
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present in the ICMPv6 header.
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The abbreviations for the types and codes may be used in rules in
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.Xr pf.conf 5 .
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The following types are defined:
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.Bl -column x xxxxxxxxxxxx -offset indent
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.It Sy Num Ta Sy Abbrev. Ta Sy Description
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.It 1 Ta unreach Ta "Destination unreachable"
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.It 2 Ta toobig Ta "Packet too big"
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.It 3 Ta timex Ta "Time exceeded"
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.It 4 Ta paramprob Ta "Invalid IPv6 header"
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.It 128 Ta echoreq Ta "Echo service request"
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.It 129 Ta echorep Ta "Echo service reply"
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.It 130 Ta groupqry Ta "Group membership query"
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.It 130 Ta listqry Ta "Multicast listener query"
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.It 131 Ta grouprep Ta "Group membership report"
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.It 131 Ta listenrep Ta "Multicast listener report"
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.It 132 Ta groupterm Ta "Group membership termination"
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.It 132 Ta listendone Ta "Multicast listener done"
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.It 133 Ta routersol Ta "Router solicitation"
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.It 134 Ta routeradv Ta "Router advertisement"
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.It 135 Ta neighbrsol Ta "Neighbor solicitation"
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.It 136 Ta neighbradv Ta "Neighbor advertisement"
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.It 137 Ta redir Ta "Shorter route exists"
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.It 138 Ta routrrenum Ta "Route renumbering"
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.It 139 Ta fqdnreq Ta "FQDN query"
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.It 139 Ta niqry Ta "Node information query"
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.It 139 Ta wrureq Ta "Who-are-you request"
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.It 140 Ta fqdnrep Ta "FQDN reply"
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.It 140 Ta nirep Ta "Node information reply"
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.It 140 Ta wrurep Ta "Who-are-you reply"
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.It 200 Ta mtraceresp Ta "mtrace response"
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.It 201 Ta mtrace Ta "mtrace messages"
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.El
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.Pp
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The following codes are defined:
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.Bl -column x xxxxxxxxxxxx xxxxxxxx -offset indent
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.It Sy Num Ta Sy Abbrev. Ta Sy Type Ta
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.Sy Description
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.It 0 Ta noroute-unr Ta unreach Ta "No route to destination"
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.It 1 Ta admin-unr Ta unreach Ta "Administratively prohibited"
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.It 2 Ta beyond-unr Ta unreach Ta "Beyond scope of source address"
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.It 2 Ta notnbr-unr Ta unreach Ta "Not a neighbor (obsolete)"
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.It 3 Ta addr-unr Ta unreach Ta "Address unreachable"
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.It 4 Ta port-unr Ta unreach Ta "Port unreachable"
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.It 0 Ta transit Ta timex Ta "Time exceeded in transit"
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.It 1 Ta reassemb Ta timex Ta "Time exceeded in reassembly"
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.It 0 Ta badhead Ta paramprob Ta "Erroneous header field"
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.It 1 Ta nxthdr Ta paramprob Ta "Unrecognized next header"
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.It 2 Ta "" Ta redir Ta "Unrecognized option"
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.It 0 Ta redironlink Ta redir Ta "Redirection to on-link node"
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.It 1 Ta redirrouter Ta redir Ta "Redirection to better router"
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.El
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.Ss Headers
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All ICMPv6 messages are prefixed with an ICMPv6 header.
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This header corresponds to the
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.Vt icmp6_hdr
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structure and has the following definition:
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.Bd -literal -offset indent
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struct icmp6_hdr {
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u_int8_t icmp6_type; /* type field */
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u_int8_t icmp6_code; /* code field */
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u_int16_t icmp6_cksum; /* checksum field */
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union {
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u_int32_t icmp6_un_data32[1]; /* type-specific */
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u_int16_t icmp6_un_data16[2]; /* type-specific */
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u_int8_t icmp6_un_data8[4]; /* type-specific */
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} icmp6_dataun;
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} __packed;
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#define icmp6_data32 icmp6_dataun.icmp6_un_data32
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#define icmp6_data16 icmp6_dataun.icmp6_un_data16
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#define icmp6_data8 icmp6_dataun.icmp6_un_data8
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#define icmp6_pptr icmp6_data32[0] /* parameter prob */
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#define icmp6_mtu icmp6_data32[0] /* packet too big */
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#define icmp6_id icmp6_data16[0] /* echo request/reply */
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#define icmp6_seq icmp6_data16[1] /* echo request/reply */
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#define icmp6_maxdelay icmp6_data16[0] /* mcast group membership*/
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.Ed
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.Pp
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.Va icmp6_type
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describes the type of the message.
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Suitable values are defined in
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.Aq Pa netinet/icmp6.h .
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.Va icmp6_code
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describes the sub-type of the message and depends on
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.Va icmp6_type .
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.Va icmp6_cksum
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contains the checksum for the message and is filled in by the
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kernel on outgoing messages.
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The other fields are used for type-specific purposes.
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.Ss Filters
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Because of the extra functionality of ICMPv6 in comparison to ICMPv4,
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a larger number of messages may be potentially received on an ICMPv6
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socket.
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Input filters may therefore be used to restrict input to a subset of the
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incoming ICMPv6 messages so only interesting messages are returned by the
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.Xr recv 2
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family of calls to an application.
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.Pp
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The
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.Vt icmp6_filter
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structure may be used to refine the input message set according to the
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ICMPv6 type.
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By default, all messages types are allowed on newly created raw ICMPv6
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sockets.
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The following macros may be used to refine the input set:
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.Bl -tag -width Ds
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.It Fn "void ICMP6_FILTER_SETPASSALL" "struct icmp6_filter *filterp"
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Allow all incoming messages.
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.Va filterp
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is modified to allow all message types.
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.It Fn "void ICMP6_FILTER_SETBLOCKALL" "struct icmp6_filter *filterp"
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Ignore all incoming messages.
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.Va filterp
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is modified to ignore all message types.
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.It Xo
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.Ft void
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.Fn ICMP6_FILTER_SETPASS "int type" "struct icmp6_filter *filterp"
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.Xc
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Allow ICMPv6 messages with the given
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.Fa type .
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.Va filterp
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is modified to allow such messages.
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.It Xo
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.Ft void
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.Fn ICMP6_FILTER_SETBLOCK" "int type" "struct icmp6_filter *filterp"
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.Xc
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Ignore ICMPv6 messages with the given
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.Fa type .
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.Va filterp
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is modified to ignore such messages.
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.It Xo
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.Ft int
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.Fn ICMP6_FILTER_WILLPASS" "int type" "const struct icmp6_filter *filterp"
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.Xc
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Determine if the given filter will allow an ICMPv6 message of the given
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type.
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.It Xo
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.Ft int
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.Fn ICMP6_FILTER_WILLBLOCK" "int type" "const struct icmp6_filter *filterp"
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.Xc
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Determine if the given filter will ignore an ICMPv6 message of the given
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type.
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.El
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.Pp
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The
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.Xr getsockopt 2
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and
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.Xr setsockopt 2
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calls may be used to obtain and install the filter on ICMPv6 sockets at
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option level
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.Dv IPPROTO_ICMPV6
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and name
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.Dv ICMPV6_FILTER
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with a pointer to the
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.Vt icmp6_filter
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structure as the option value.
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.Sh SEE ALSO
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.Xr getsockopt 2 ,
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.Xr recv 2 ,
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.Xr send 2 ,
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.Xr setsockopt 2 ,
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.Xr socket 2 ,
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.Xr getprotobyname 3 ,
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.Xr inet6 4 ,
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.Xr ip6 4 ,
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.Xr netintro 4
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.Rs
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.%A W. Stevens
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.%A M. Thomas
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.%T Advanced Sockets API for IPv6
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.%N RFC 2292
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.%D February 1998
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.Re
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.Rs
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.%A A. Conta
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.%A S. Deering
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.%T "Internet Control Message Protocol (ICMPv6) for the Internet" \
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"Protocol Version 6 (IPv6) Specification"
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.%N RFC 2463
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.%D December 1998
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.Re
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