ICMP6(4P) Protocols ICMP6(4P)

NAME

icmp6 - Internet Control Message Protocol for Internet Protocol Version 6

SYNOPSIS

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


s = socket(AF_INET6, SOCK_RAW, proto);


t = t_open("/dev/icmp6", O_RDWR);

DESCRIPTION

The ICMP6 protocol is the error and control message protocol used with
Version 6 of the Internet Protocol. It is used by the kernel to handle
and report errors in protocol processing. It is also used for IPv6
neighbor and router discovery, and for multicast group membership queries
and reports. It may also be accessed by programs using the socket
interface or the Transport Level Interface (TLI) for network monitoring
and diagnostic functions. When used with the socket interface, a "raw
socket" type is used. The protocol number for ICMP6, used in the proto
parameter to the socket call, can be obtained from
getprotobyname(3SOCKET). ICMP6 file descriptors and sockets are
connectionless and are normally used with the t_sndudata / t_rcvudata and
the sendto() / recvfrom() calls. They may also be used with the
sendmsg()/recvgmsg() calls when sending or receiving ancillary data. In
order to send ICMP6 packets, a process needs the PRIV_NET_ICMPACCESS
privilege. (See privileges(7) for more information on privileges.)


Outgoing packets automatically have an Internet Protocol Version 6 (IPv6)
header and zero or more IPv6 extension headers prepended. These headers
are prepended by the kernel. Unlike ICMP for IPv4, the IP_HDRINCL option
is not supported for ICMP6, so ICMP6 applications neither build their own
outbound IPv6 headers, nor do they receive the inbound IPv6 headers with
received data. IPv6 extension headers and relevant fields of the IPv6
header may be set or received as ancillary data to a sendmsg(3SOCKET) or
recvmsg(3SOCKET) system call. Each of these fields and extension headers
may also be set on a per socket basis with the setsockopt(3SOCKET) system
call. Such "sticky" options are used on all outgoing packets unless
overridden by ancillary data. When any ancillary data is present with a
sendmsg(3SOCKET) system call, all sticky options are ignored for that
system call, but subsequently remain configured.


ICMP6 is a datagram protocol layered above IPv6. Received ICMP6 messages
may be reflected back to users of higher-level protocols such as TCP or
UDP as error returns from system calls. A copy of each ICMP6 error
message received by the system is provided to every holder of an open
ICMP6 socket or TLI descriptor.

SEE ALSO

t_rcvudata(3NSL), t_sndudata(3NSL), getprotobyname(3SOCKET),
recv(3SOCKET), recvmsg(3SOCKET), send(3SOCKET), sendmsg(3SOCKET),
setsockopt(3SOCKET), inet6(4P), ip6(4P), routing(4P), privileges(7)


Conta, A. and Deering, S., RFC 2463, Internet Control Message Protocol
(ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification, The
Internet Society, December 1998.

DIAGNOSTICS

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

EISCONN
An attempt was made 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 connected.


ENOTCONN
An attempt was made to send a datagram, but no
destination address is specified, and the socket has not
been connected.


ENOBUFS
The system ran out of memory for an internal data
structure.


EADDRNOTAVAIL
An attempt was made to create a socket with a network
address for which no network interface exists.


ENOMEM
The system was unable to allocate memory for an internal
data structure.


ENOPROTOOPT
An attempt was made to set an IPv4 socket option on an
IPv6 socket.


EINVAL
An attempt was made to set an invalid or malformed
socket option.


EAFNOSUPPORT
An attempt was made to bind or connect to an IPv4 or
mapped address, or to specify an IPv4 or mapped address
as the next hop.


December 3, 2015 ICMP6(4P)