Protocols ip6(7P)
NAME
ip6 - Internet Protocol Version 6
SYNOPSIS
#include
#include
#include
s = socket(AFINET6, SOCKRAW, proto);
t = topen ("/dev/rawip6", ORDWR);
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 extension headers defined in the IPv6 specification may
be set in outgoing datagrams.
APLICATION PROGRAMING 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
IPHDRINCL socket option. IPv6 header values may be speci-
fied 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 ancil-
lary data. If any ancillary data is specified in a
sendmsg(3SOCKET) call, all sticky options not explicitly
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Protocols ip6(7P)
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 SOCKSTREAM
upper level protocols such as TCP, ancillary data is unsup-
ported for TCP. Sticky options, however, are supported.
Since sendmsg(3SOCKET) is supported for SOCKDGRAM 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:
IPV6BOUNDIF Limit reception and transmission of
packets to this interface. Takes an
integer as an argument; the integer
is the selected interace index.
IPV6UNSPECSRC Boolean. Allow/disallow sending with
a zero source address.
IPV6UNICASTHOPS Default hop limit for unicast
datagrams. This option takes an
integer as an argument. Its value
becomes the new default value for
ip6hops that IPv6 will use on out-
going unicast datagrams sent from
that socket. The initial default is
60.
IPV6CHECKSUM 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.
IPV6SECOPT Enable or obtain IPsec security set-
tings for this socket. For more
details on the protection services
of IPsec, see ipsec(7P).
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Protocols ip6(7P)
IPV6DONTFRAG Boolean. Control fragmentation.
IPV6USEMINMTU 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.
IPV6V6ONLY Boolean. If set, only V6 packets can
be sent or received
IPV6SRCPREFERENCES 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:
IPV6RECVPKTINFO Enable/disable receipt of the index
of the interface the packet arrived
on, and of the inbound packet's
destination address.
IPV6RECVHOPLIMIT Enable/disable receipt of the
inbound packet's current hoplimit.
IPV6RECVHOPOPTS Enable/disable receipt of the
inbound packet's IPv6 hop-by-hop
extension header.
IPV6RECVDSTOPTS Enable/disable receipt of the
inbound packet's IPv6 destination
options extension header.
IPV6RECVRTHDR Enable/disable receipt of the
inbound packet's IPv6 routing
header.
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Protocols ip6(7P)
IPV6RECVRTHDRDSTOPTS Enable/disable receipt of the
inbound packet's intermediate-hops
options extension header. This
option is obsolete.
IPV6RECVDSTOPTS turns on receipt
of both destination option headers.
IPV6RECVTCLAS Enable/disable receipt of the
traffic class of the inbound
packet.
IPV6RECVPATHMTU 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:
IPV6PKTINFO Set the source address and/or interface
out which the packet(s) will be sent.
Takes a struct in6pktinfo as the
parameter.
IPV6HOPLIMIT 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
IPV6UNICASTHOPS and
IPV6MULTICASTHOPS to change the
socket's default hoplimit.
IPV6NEXTHOP Specify the IPv6 address of the first
hop, which must be a neighbor of the
sending host. Takes a struct
sockaddrin6 as the parameter. When
this option specifies the same address
as the destination IPv6 address of the
datagram, this is equivalent to the
existing SODONTROUTE option.
IPV6HOPOPTS Specify one or more hop-by-hop options.
Variable length. Takes a complete IPv6
hop-by-hop options extension header as
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Protocols ip6(7P)
the parameter.
IPV6DSTOPTS Specify one or more destination
options. Variable length. Takes a com-
plete IPv6 destination options exten-
sion header as the parameter.
IPV6RTHDR Specify the IPv6 routing header. Vari-
able length. Takes a complete IPv6
routing header as the parameter.
Currently, only type 0 routing headers
are supported.
IPV6RTHDRDSTOPTS Specify one or more destination options
for all intermediate hops. May be con-
figured, but will not be applied unless
an IPv6 routing header is also config-
ured. Variable length. Takes a complete
IPv6 destination options extension
header as the parameter.
IPV6PATHMTU Get the path MTU associated with a con-
nected socket. Takes a ip6mtuinfo as
the parameter.
IPV6TCLAS 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:
IPV6JOINGROUP Join a multicast group. Takes a
struct ipv6mreq as the parame-
ter; the structure contains a
multicast address and an inter-
face index.
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Protocols ip6(7P)
IPV6LEAVEGROUP Leave a multicast group. Takes a
struct ipv6mreq as the parame-
ter; the structure contains a
multicast address and an inter-
face index.
MCASTJOINGROUP Functionally equivalent to
IPV6JOINGROUP. Takes a struct
groupreq as the parameter. The
structure contains a multicast
address and an interface index.
MCASTBLOCKSOURCE Block multicast packets on a
particular multicast group whose
source address matches the given
source address. The specified
group must be joined previously
using IPV6JOINGROUP or
MCASTJOINGROUP. Takes a struct
groupsourcereq as the parame-
ter. The structure contains an
interface index, a multicast
address, and a source address.
MCASTUNBLOCKSOURCE Unblock multicast packets which
were previously blocked using
MCASTBLOCKSOURCE. Takes a
struct groupsourcereq as the
parameter. The structure con-
tains an interface index, a mul-
ticast address, and a source
address.
MCASTLEAVEGROUP Functionally equivalent to
IPV6LEAVEGROUP. Takes a struct
groupreq as the parameter. The
structure contains a multicast
address and an interface index.
MCASTJOINSOURCEGROUP Begin receiving packets for the
given multicast group whose
source address matches the
specified address. Takes a
struct groupsourcereq as the
parameter. The structure con-
tains an interface index, a mul-
ticast address, and a source
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Protocols ip6(7P)
address.
MCASTLEAVESOURCEGROUP Stop receiving packets for the
given multicast group whose
source address matches the
specified address. Takes a
struct groupsourcereq as the
parameter. The structure con-
tains an interface index, a mul-
ticast address, and a source
address.
IPV6MULTICASTIF The outgoing interface for mul-
ticast packets. This option
takes an integer as an argument;
the integer is the interface
index of the selected interface.
IPV6MULTICASTHOPS Default hop limit for multicast
datagrams. This option takes an
integer as an argument. Its
value becomes the new default
value for ip6hops that IPv6
will use on outgoing multicast
datagrams sent from that socket.
The initial default is 1.
IPV6MULTICASTLOP 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 SODONTROUTE 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.
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Protocols ip6(7P)
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 Con-
trol 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 IPV6CHECKSUM 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 sup-
ported), and fragment header.
By default, the IPv6 layer will not forward IPv6 packets
that are not addressed to it. This behavior can be overrid-
den 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 ipforwarding variable. It is
set to 1 if IPv6 forwarding is enabled, or 0 if it is dis-
abled.
Additionally, finer-grained forwarding can be configured in
IPv6. Each interface can be configured to forward IPv6 pack-
ets by setting the IFROUTER interface flag. This flag can
be set and cleared using ifconfig(1M)'s router and -router
options. If an interface's IFROUTER 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
ip6forwarding variable sets all of the IPv6 interfaces'
IFROUTER flags.
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Protocols ip6(7P)
For backwards compatibility, each interface creates an
ip6forwarding /dev/ip6 variable that can be modi-
fied using ndd(1M). An interface's :ip6forwarding ndd vari-
able is a boolean variable that mirrors the status of its
IFROUTER interface flag. It is set to 1 if the flag is
set, or 0 if it is clear. This interface specific
:ip6forwarding ndd variable is obsolete and may be
removed in a future release of Solaris. The ifconfig(1M)
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 ip6hops field in the IPv6 header drops to zero in the
process of forwarding a datagram. A "destination unreach-
able" 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 prob-
lem with a field in the IPv6 header or any of the IPv6
extension headers such that the packet cannot be fully pro-
cessed.
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 recon-
structed 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), 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), iftcp(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.
SunOS 5.11 Last change: 2 Dec 2008 9
Protocols ip6(7P)
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:
EPROTONOSUPORT Unsupported protocol (for example,
IPROTORAW.)
EACES A bind() operation was attempted with a
"reserved" port number and the effective
user ID of the process was not the
privileged user.
EADRINUSE A bind() operation was attempted on a
socket with a network address/port pair
that has already been bound to another
socket.
EADRNOTAVAIL A bind() operation was attempted for an
address that is not configured on this
machine.
EINVAL A sendmsg() operation with a non-NUL
msgaccrights 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.
EISCON 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
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Protocols ip6(7P)
before making the new connection.
EISCON A sendto() or sendmsg() operation speci-
fying 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() opera-
tion 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 con-
nection 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.
ENOTCON A send() or write() operation, or a
sendto() or sendmsg() operation not
specifying an address to which the mes-
sage 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 fragmen-
tation buffers or other internal data
structures.
ENOMEM The system was unable to allocate memory
for an IPv6 socket option or other inter-
nal data structures.
ENOPROTOPT An IP socket option was attempted on an
IPv6 socket, or an IPv6 socket option was
attempted on an IP socket.
ENOPROTOPT Invalid socket type for the option.
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Protocols ip6(7P)
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 facil-
ity, 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 5.11 Last change: 2 Dec 2008 12
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