ip6(7P) Protocols ip6(7P)NAMEip6 - 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(7P) and udp(7P). 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 exten‐
sion 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 pro‐
vides 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 destina‐
tion 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 set‐
sockopt(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 proto‐
cols, 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 transmission of packets to this
interface. Takes an integer as an argument; the
integer is the selected interace 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 check‐
sum 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(7P).
IPV6_DONTFRAG Boolean. Control fragmentation.
IPV6_USE_MIN_MTU Boolean. Use the minimum MTU for transmitting
traffic.
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(7P).
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 setsock‐
opt(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 destina‐
tion IPv6 address of the datagram, this is equiva‐
lent 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 param‐
eter. 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 param‐
eter.
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 inter‐
face index.
IPV6_LEAVE_GROUP Leave a multicast group. Takes a struct
ipv6_mreq as the parameter; the structure
contains a multicast address and an inter‐
face 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 spec‐
ified 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 previ‐
ously blocked using MCAST_BLOCK_SOURCE.
Takes a struct group_source_req as the
parameter. The structure contains an inter‐
face 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 mul‐
ticast 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 multi‐
cast 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 pack‐
ets. 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 argu‐
ment. 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 mem‐
bers 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 forward‐
ing 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 connec‐
tionless primitives.
Datagrams flow through the IPv6 layer in two directions: from the net‐
work 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(7P).
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(1M)
to enable the ipv6-forwarding option. IPv6 forwarding is configured at
boot time based on the setting of routeadm(1M)'s ipv6-forwarding
option.
For backwards compatibility, IPv6 forwarding can be enabled or disabled
using ndd(1M)'s ip_forwarding variable. It is set to 1 if IPv6 for‐
warding 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(1M)'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 oth‐
ers, nor forwarded to this interface. Setting the ip6_forwarding vari‐
able sets all of the IPv6 interfaces' IFF_ROUTER flags.
For backwards compatibility, each interface creates an <ifname>ip6_for‐
warding /dev/ip6 variable that can be modified using ndd(1M). 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(1M) router and -router inter‐
faces 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 "desti‐
nation unreachable" message will be sent by a router or by the origi‐
nating 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 encoun‐
ters 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 trans‐
mission unit (MTU) of the network interface. Fragments of received
datagrams are dropped from the reassembly queues if the complete data‐
gram 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 ALSOsvcs(1), ndd(1M), routeadm(1M), svcadm(1M), read(2), write(2),
bind(3SOCKET), connect(3SOCKET), getsockopt(3SOCKET), recv(3SOCKET),
recvmsg(3SOCKET), send(3SOCKET), sendmsg(3SOCKET), setsockopt(3SOCKET),
defaultrouter(4), smf(5), icmp6(7P), if_tcp(7P), ipsec(7P), inet6(7P),
routing(7P), tcp(7P), udp(7P)
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 per‐
formed, 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 "destina‐
tion 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 buf‐
fers 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(5),
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(1M). The service's
status can be queried using the svcs(1) command.
SunOS 5.10 5 May 2007 ip6(7P)
