IP6(4P) Protocols IP6(4P)

NAME

ip6 - Internet Protocol Version 6

SYNOPSIS

#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip6.h>


s = socket(AF_INET6, SOCK_RAW, proto);


t = t_open ("/dev/rawip6", O_RDWR);

DESCRIPTION

The IPv6 protocol is the next generation of the internetwork datagram
delivery protocol of the Internet protocol family. Programs may use IPv6
through higher-level protocols such as the Transmission Control Protocol
(TCP) or the User Datagram Protocol (UDP), or may interface directly to
IPv6. See tcp(4P) and udp(4P). Direct access may be by means of the
socket interface, using a "raw socket," or by means of the Transport
Level Interface (TLI). The protocol options and IPv6 extension headers
defined in the IPv6 specification may be set in outgoing datagrams.

APPLICATION PROGRAMMING INTERFACE

The STREAMS driver /dev/rawip6 is the TLI transport provider that
provides raw access to IPv6.


Raw IPv6 sockets are connectionless and are normally used with the
sendto() and recvfrom() calls (see send(3SOCKET) and recv(3SOCKET)),
although the connect(3SOCKET) call may also be used to fix the
destination for future datagrams. In this case, the read(2) or
recv(3SOCKET) and write(2) or send(3SOCKET) calls may be used. Ancillary
data may also be sent or received over raw IPv6 sockets using the
sendmsg(3SOCKET) and recvmsg(3SOCKET) system calls.


Unlike raw IP, IPv6 applications do not include a complete IPv6 header
when sending; there is no IPv6 analog to the IP IP_HDRINCL socket option.
IPv6 header values may be specified or received as ancillary data to a
sendmsg(3SOCKET) or recvmsg(3SOCKET) system call, or may be specified as
"sticky" options on a per-socket basis by using the setsockopt(3SOCKET)
system call. Such sticky options are applied to all outbound packets
unless overridden by ancillary data. If any ancillary data is specified
in a sendmsg(3SOCKET) call, all sticky options not explicitly overridden
revert to default values for that datagram only; the sticky options
persist as set for subsequent datagrams.


Since sendmsg(3SOCKET) is not supported for SOCK_STREAM upper level
protocols such as TCP, ancillary data is unsupported for TCP. Sticky
options, however, are supported.


Since sendmsg(3SOCKET) is supported for SOCK_DGRAM upper level protocols,
both ancillary data and sticky options are supported for UDP, ICMP6, and
raw IPv6 sockets.


The socket options supported at the IPv6 level are:

IPV6_BOUND_IF
Limit reception and transmission of packets to
this interface. Takes an integer as an argument;
the integer is the selected interface index.


IPV6_UNSPEC_SRC
Boolean. Allow/disallow sending with a zero
source address.


IPV6_UNICAST_HOPS
Default hop limit for unicast datagrams. This
option takes an integer as an argument. Its value
becomes the new default value for ip6_hops that
IPv6 will use on outgoing unicast datagrams sent
from that socket. The initial default is 60.


IPV6_CHECKSUM
Specify the integer offset in bytes into the user
data of the checksum location. Does not apply to
the ICMP6 protocol. Note: checksums are required
for all IPv6 datagrams; this is different from
IP, in which datagram checksums were optional.
IPv6 will compute the ULP checksum if the value
in the checksum field is zero.


IPV6_SEC_OPT
Enable or obtain IPsec security settings for this
socket. For more details on the protection
services of IPsec, see ipsec(4P).


IPV6_DONTFRAG
Boolean. Control fragmentation.


IPV6_USE_MIN_MTU
Controls whether path MTU discovery is used. If
set to 1, path MTU discovery is never used and
IPv6 packets are sent with the IPv6 minimum MTU.
If set to -1, path MTU discovery is not used for
multicast and multicast packets are sent with the
IPv6 minimum MTU. If set to 0, path MTU is
always performed.


IPV6_V6ONLY
Boolean. If set, only V6 packets can be sent or
received


IPV6_SRC_PREFERENCES
Enable or obtain Source Address Selection rule
settings for this socket. For more details on the
Source Address Selection rules, see inet6(4P).


The following options are boolean switches controlling the reception of
ancillary data:

IPV6_RECVPKTINFO
Enable/disable receipt of the index of the
interface the packet arrived on, and of the
inbound packet's destination address.


IPV6_RECVHOPLIMIT
Enable/disable receipt of the inbound packet's
current hoplimit.


IPV6_RECVHOPOPTS
Enable/disable receipt of the inbound packet's
IPv6 hop-by-hop extension header.


IPV6_RECVDSTOPTS
Enable/disable receipt of the inbound packet's
IPv6 destination options extension header.


IPV6_RECVRTHDR
Enable/disable receipt of the inbound packet's
IPv6 routing header.


IPV6_RECVRTHDRDSTOPTS
Enable/disable receipt of the inbound packet's
intermediate-hops options extension header. This
option is obsolete. IPV6_RECVDSTOPTS turns on
receipt of both destination option headers.


IPV6_RECVTCLASS
Enable/disable receipt of the traffic class of
the inbound packet.


IPV6_RECVPATHMTU
Enable/disable receipt of the path mtu of the
inbound packet.


The following options may be set as sticky options with
setsockopt(3SOCKET) or as ancillary data to a sendmsg(3SOCKET) system
call:

IPV6_PKTINFO
Set the source address and/or interface out which
the packet(s) will be sent. Takes a struct
in6_pktinfo as the parameter.


IPV6_HOPLIMIT
Set the initial hoplimit for outbound datagrams.
Takes an integer as the parameter. Note: This option
sets the hoplimit only for ancillary data or sticky
options and does not change the default hoplimit for
the socket; see IPV6_UNICAST_HOPS and
IPV6_MULTICAST_HOPS to change the socket's default
hoplimit.


IPV6_NEXTHOP
Specify the IPv6 address of the first hop, which
must be a neighbor of the sending host. Takes a
struct sockaddr_in6 as the parameter. When this
option specifies the same address as the destination
IPv6 address of the datagram, this is equivalent to
the existing SO_DONTROUTE option.


IPV6_HOPOPTS
Specify one or more hop-by-hop options. Variable
length. Takes a complete IPv6 hop-by-hop options
extension header as the parameter.


IPV6_DSTOPTS
Specify one or more destination options. Variable
length. Takes a complete IPv6 destination options
extension header as the parameter.


IPV6_RTHDR
Specify the IPv6 routing header. Variable length.
Takes a complete IPv6 routing header as the
parameter. Currently, only type 0 routing headers
are supported.


IPV6_RTHDRDSTOPTS
Specify one or more destination options for all
intermediate hops. May be configured, but will not
be applied unless an IPv6 routing header is also
configured. Variable length. Takes a complete IPv6
destination options extension header as the
parameter.


IPV6_PATHMTU
Get the path MTU associated with a connected socket.
Takes a ip6_mtuinfo as the parameter.


IPV6_TCLASS
Set the traffic class associated with outgoing
packets. The parameter is an integer. If the
parameter is less then -1 or greater then 256,
EINVAL is returned. If the parameter is equal to -1,
use the default. If the parameter is between 0 and
255 inclusive, use that value.


The following options affect the socket's multicast behavior:

IPV6_JOIN_GROUP
Join a multicast group. Takes a struct
ipv6_mreq as the parameter; the structure
contains a multicast address and an interface
index.


IPV6_LEAVE_GROUP
Leave a multicast group. Takes a struct
ipv6_mreq as the parameter; the structure
contains a multicast address and an interface
index.


MCAST_JOIN_GROUP
Functionally equivalent to IPV6_JOIN_GROUP.
Takes a struct group_req as the parameter.
The structure contains a multicast address
and an interface index.


MCAST_BLOCK_SOURCE
Block multicast packets on a particular
multicast group whose source address matches
the given source address. The specified group
must be joined previously using
IPV6_JOIN_GROUP or MCAST_JOIN_GROUP. Takes a
struct group_source_req as the parameter. The
structure contains an interface index, a
multicast address, and a source address.


MCAST_UNBLOCK_SOURCE
Unblock multicast packets which were
previously blocked using MCAST_BLOCK_SOURCE.
Takes a struct group_source_req as the
parameter. The structure contains an
interface index, a multicast address, and a
source address.


MCAST_LEAVE_GROUP
Functionally equivalent to IPV6_LEAVE_GROUP.
Takes a struct group_req as the parameter.
The structure contains a multicast address
and an interface index.


MCAST_JOIN_SOURCE_GROUP
Begin receiving packets for the given
multicast group whose source address matches
the specified address. Takes a struct
group_source_req as the parameter. The
structure contains an interface index, a
multicast address, and a source address.


MCAST_LEAVE_SOURCE_GROUP
Stop receiving packets for the given
multicast group whose source address matches
the specified address. Takes a struct
group_source_req as the parameter. The
structure contains an interface index, a
multicast address, and a source address.


IPV6_MULTICAST_IF
The outgoing interface for multicast packets.
This option takes an integer as an argument;
the integer is the interface index of the
selected interface.


IPV6_MULTICAST_HOPS
Default hop limit for multicast datagrams.
This option takes an integer as an argument.
Its value becomes the new default value for
ip6_hops that IPv6 will use on outgoing
multicast datagrams sent from that socket.
The initial default is 1.


IPV6_MULTICAST_LOOP
Loopback for multicast datagrams. Normally
multicast datagrams are delivered to members
on the sending host. Setting the unsigned
character argument to 0 will cause the
opposite behavior.


The multicast socket options can be used with any datagram socket type in
the IPv6 family.


At the socket level, the socket option SO_DONTROUTE may be applied. This
option forces datagrams being sent to bypass routing and forwarding by
forcing the IPv6 hoplimit field to 1, meaning that the packet will not be
forwarded by routers.


Raw IPv6 datagrams can also be sent and received using the TLI
connectionless primitives.


Datagrams flow through the IPv6 layer in two directions: from the network
up to user processes and from user processes down to the network. Using
this orientation, IPv6 is layered above the network interface drivers and
below the transport protocols such as UDP and TCP. The Internet Control
Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) is
logically a part of IPv6. See icmp6(4P).


Unlike IP, IPv6 provides no checksum of the IPv6 header. Also unlike IP,
upper level protocol checksums are required. IPv6 will compute the
ULP/data portion checksum if the checksum field contains a zero (see
IPV6_CHECKSUM option above).


IPv6 extension headers in received datagrams are processed in the IPv6
layer according to the protocol specification. Currently recognized IPv6
extension headers include hop-by-hop options header, destination options
header, routing header (currently, only type 0 routing headers are
supported), and fragment header.


By default, the IPv6 layer will not forward IPv6 packets that are not
addressed to it. This behavior can be overridden by using routeadm(8) to
enable the ipv6-forwarding option. IPv6 forwarding is configured at boot
time based on the setting of routeadm(8)'s ipv6-forwarding option.


For backwards compatibility, IPv6 forwarding can be enabled or disabled
using ndd(8)'s ip_forwarding variable. It is set to 1 if IPv6 forwarding
is enabled, or 0 if it is disabled.


Additionally, finer-grained forwarding can be configured in IPv6. Each
interface can be configured to forward IPv6 packets by setting the
IFF_ROUTER interface flag. This flag can be set and cleared using
ifconfig(8)'s router and -router options. If an interface's IFF_ROUTER
flag is set, packets can be forwarded to or from the interface. If it is
clear, packets will neither be forwarded from this interface to others,
nor forwarded to this interface. Setting the ip6_forwarding variable
sets all of the IPv6 interfaces' IFF_ROUTER flags.


For backwards compatibility, each interface creates an
<ifname>ip6_forwarding /dev/ip6 variable that can be modified using
ndd(8). An interface's :ip6_forwarding ndd variable is a boolean variable
that mirrors the status of its IFF_ROUTER interface flag. It is set to 1
if the flag is set, or 0 if it is clear. This interface specific
<ifname>:ip6_forwarding ndd variable is obsolete and may be removed in a
future release of Solaris. The ifconfig(8) router and -router interfaces
are preferred.


The IPv6 layer will send an ICMP6 message back to the source host in many
cases when it receives a datagram that can not be handled. A "time
exceeded" ICMP6 message will be sent if the ip6_hops field in the IPv6
header drops to zero in the process of forwarding a datagram. A
"destination unreachable" message will be sent by a router or by the
originating host if a datagram can not be sent on because there is no
route to the final destination; it will be sent by a router when it
encounters a firewall prohibition; it will be sent by a destination node
when the transport protocol (that is, TCP) has no listener. A "packet too
big" message will be sent by a router if the packet is larger than the
MTU of the outgoing link (this is used for Path MTU Discovery). A
"parameter problem" message will be sent if there is a problem with a
field in the IPv6 header or any of the IPv6 extension headers such that
the packet cannot be fully processed.


The IPv6 layer supports fragmentation and reassembly. Datagrams are
fragmented on output if the datagram is larger than the maximum
transmission unit (MTU) of the network interface. Fragments of received
datagrams are dropped from the reassembly queues if the complete datagram
is not reconstructed within a short time period.


Errors in sending discovered at the network interface driver layer are
passed by IPv6 back up to the user process.

SEE ALSO

svcs(1), read(2), write(2), bind(3SOCKET), connect(3SOCKET),
getsockopt(3SOCKET), recv(3SOCKET), recvmsg(3SOCKET), send(3SOCKET),
sendmsg(3SOCKET), setsockopt(3SOCKET), icmp6(4P), if_tcp(4P), inet6(4P),
ipsec(4P), routing(4P), tcp(4P), udp(4P), defaultrouter(5), smf(7),
ndd(8), routeadm(8), svcadm(8)


Deering, S. and Hinden, B. RFC 2460, Internet Protocol, Version 6 (IPv6)
Specification. The Internet Society. December, 1998.


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

DIAGNOSTICS

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

EPROTONOSUPPORT
Unsupported protocol (for example, IPPROTO_RAW.)


EACCES
A bind() operation was attempted with a "reserved"
port number and the effective user ID of the process
was not the privileged user.


EADDRINUSE
A bind() operation was attempted on a socket with a
network address/port pair that has already been bound
to another socket.


EADDRNOTAVAIL
A bind() operation was attempted for an address that
is not configured on this machine.


EINVAL
A sendmsg() operation with a non-NULL msg_accrights
was attempted.


EINVAL
A getsockopt() or setsockopt() operation with an
unknown socket option name was given.


EINVAL
A getsockopt() or setsockopt() operation was attempted
with the IPv6 option field improperly formed; an
option field was shorter than the minimum value or
longer than the option buffer provided; the value in
the option field was invalid.


EISCONN
A connect() operation was attempted on a socket on
which a connect() operation had already been
performed, and the socket could not be successfully
disconnected before making the new connection.


EISCONN
A sendto() or sendmsg() operation specifying an
address to which the message should be sent was
attempted on a socket on which a connect() operation
had already been performed.


EMSGSIZE
A send(), sendto(), or sendmsg() operation was
attempted to send a datagram that was too large for an
interface, but was not allowed to be fragmented (such
as broadcasts).


ENETUNREACH
An attempt was made to establish a connection via
connect(), or to send a datagram by means of sendto()
or sendmsg(), where there was no matching entry in the
routing table; or if an ICMP "destination unreachable"
message was received.


ENOTCONN
A send() or write() operation, or a sendto() or
sendmsg() operation not specifying an address to which
the message should be sent, was attempted on a socket
on which a connect() operation had not already been
performed.


ENOBUFS
The system ran out of memory for fragmentation buffers
or other internal data structures.


ENOMEM
The system was unable to allocate memory for an IPv6
socket option or other internal data structures.


ENOPROTOOPT
An IP socket option was attempted on an IPv6 socket,
or an IPv6 socket option was attempted on an IP
socket.


ENOPROTOOPT
Invalid socket type for the option.

NOTES

Applications using the sockets API must use the Advanced Sockets API for
IPv6 (RFC 2292) to see elements of the inbound packet's IPv6 header or
extension headers.


The ip6 service is managed by the service management facility, smf(7),
under the service identifier:

svc:/network/initial:default


Administrative actions on this service, such as enabling, disabling, or
requesting restart, can be performed using svcadm(8). The service's
status can be queried using the svcs(1) command.

December 28, 2020 IP6(4P)