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ICMP6(4)		 BSD Kernel Interfaces Manual		      ICMP6(4)

     icmp6 -- Internet Control Message Protocol	for IPv6

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

     socket(AF_INET6, SOCK_RAW,	proto);

     ICMPv6 is the error and control message protocol used by IPv6 and the In-
     ternet 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 recvfrom(2)
     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).  ICMPv6 pseudo	header checksum	field
     (icmp6_cksum) will	be filled automatically	by the kernel.	Incoming pack-
     ets are received without the IPv6 header nor IPv6 extension headers.  No-
     tice that this behavior is	opposite from IPv4 raw sockets and.  ICMPv4

   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>

     The current filter	is fetched and stored using getsockopt(2) and
     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 *filterp)

	   void	ICMP6_FILTER_SETBLOCKALL(struct	icmp6_filter *filterp)

	   void	ICMP6_FILTER_SETPASS(int type, struct icmp6_filter *filterp)

	   void	ICMP6_FILTER_SETBLOCK(int type,	struct icmp6_filter *filterp)

	   int ICMP6_FILTER_WILLPASS(int type, const struct icmp6_filter

	   int ICMP6_FILTER_WILLBLOCK(int type,	const struct icmp6_filter

     The first argument	to the last four macros	(an integer) is	an ICMPv6 mes-
     sage 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, let us 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,	let us 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	de-
     pending 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 RFC2292.

     A socket operation	may fail with one of the following errors returned:

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

     [ENOTCONN]		when trying to send a datagram,	but no destination ad-
			dress is specified, and	the socket hasn't been con-

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

     [EADDRNOTAVAIL]	when an	attempt	is made	to create a socket with	a net-
			work address for which no network interface exists.

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

     W.	Stevens	and M. Thomas, Advanced	Sockets	API for	IPv6, RFC, 2292,
     February 1998.

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

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

     Part of the document was shamelessly copied from RFC2292.

BSD				March 13, 2000				   BSD


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