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NAME    [Toc]    [Back]

     icmp6 - Internet Control Message Protocol for IPv6

SYNOPSIS    [Toc]    [Back]

     #include <sys/socket.h>
     #include <netinet/in.h>
     #include <netinet/icmp6.h>

     socket(AF_INET6, SOCK_RAW, proto);

DESCRIPTION    [Toc]    [Back]

     ICMPv6 is the error and control  message  protocol  used  by
IPv6 and the Internet
  protocol family.  It may be accessed through a ``raw
socket'' for
     network monitoring and diagnostic functions.  The proto  parameter to the
     socket call to create an ICMPv6 socket is obtained from
     getprotobyname(3),  or  you  can use IPPROTO_ICMPV6.  ICMPv6
sockets are
     connectionless, and are normally used with the sendto(2) and
     calls,  though  the  connect(2) call may also be used to fix
the destination
     for future packets (in which case the read(2) or recv(2) and
write(2) or
     send(2) system calls may be used).

     Outgoing packets automatically have an IPv6 header prepended
to them
     (based on the destination address).  The ICMPv6 pseudo-header checksum
     field  (icmp6_cksum)  is filled automatically by the kernel.
     packets are received without the IPv6 header or IPv6  extension headers.
     Notice  that  this  behavior is opposite to that of IPv4 raw
sockets and
     ICMPv4 sockets.

   ICMPv6 type/code filter
     Each ICMPv6  raw  socket  has  an  associated  filter  whose
datatype is defined
     as struct icmp6_filter;

     This  structure, along with the macros and constants defined
later in this
     section,  are  defined  as  a  result   of   including   the
<netinet/icmp6.h> header.

     The current filter is fetched and stored using getsockopt(2)
     setsockopt(2) with a level of IPPROTO_ICMPV6 and  an  option
name of

     Six macros operate on an icmp6_filter structure:

           void ICMP6_FILTER_SETPASSALL(struct icmp6_filter *)
           void ICMP6_FILTER_SETBLOCKALL(struct icmp6_filter *)
           void ICMP6_FILTER_SETPASS(int, struct icmp6_filter *)
           void ICMP6_FILTER_SETBLOCK(int, struct icmp6_filter *)
           int    ICMP6_FILTER_WILLPASS(int,     const     struct
icmp6_filter *)
           int     ICMP6_FILTER_WILLBLOCK(int,    const    struct
icmp6_filter *)

     The first argument to the last four macros (an  integer)  is
an ICMPv6 message
  type,  between 0 and 255.  The pointer argument to all
six macros is
     a pointer to a filter that is modified  by  the  first  four
macros examined
     by the last two macros.

     The  first  two  macros, SETPASSALL and SETBLOCKALL, specify
that all ICMPv6
     messages are passed to the application or  that  all  ICMPv6
messages are
     blocked from being passed to the application.

     The next two macros, SETPASS and SETBLOCK, specify that messages of a
     given ICMPv6 type should be passed to the application or not
passed to
     the application (blocked).

     The final two macros, WILLPASS and WILLBLOCK, return true or
false depending
 on whether the specified message type is  passed  to
the application
  or blocked from being passed to the application by the
filter pointed
 to by the second argument.

     When an ICMPv6 raw socket is created,  it  will  by  default
pass all ICMPv6
     message types to the application.

     For further discussions see RFC 2292.

DIAGNOSTICS    [Toc]    [Back]

     A socket operation may fail with one of the following errors

     [EISCONN]        when trying to establish a connection on  a
socket which
                      already  has  one, or when trying to send a
datagram with
                      the destination address specified  and  the
socket is already

     [ENOTCONN]       when trying to send a datagram, but no destination address
 is specified, and the  socket  hasn't
been connected.

     [ENOBUFS]         when  the system runs out of memory for an
internal data

     [EADDRNOTAVAIL]  when an attempt is made to create a  socket
with a network
 address for which no network interface

SEE ALSO    [Toc]    [Back]

     recv(2), send(2), inet6(4), ip6(4), netintro(4)

     W. Stevens and M. Thomas, Advanced Sockets API for IPv6, RFC
     February 1998.

     A.  Conta  and S. Deering, Internet Control Message Protocol
(ICMPv6) for
     the Internet Protocol Version 6  (IPv6)  Specification,  RFC
2463, December

HISTORY    [Toc]    [Back]

     The  implementation  is  based on KAME stack (which is a descendant of WIDE
     hydrangea IPv6 stack kit).

     Part of the document was shamelessly copied from RFC 2292.

OpenBSD     3.6                        December     17,      1999
[ Back ]
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