ipv6 — Linux IPv6 protocol implementation
#include <sys/socket.h> #include <netinet/in.h>
tcp6_socket =
socket( |
AF_INET6, |
| SOCK_STREAM, | |
0); |
raw6_socket =
socket( |
AF_INET6, |
| SOCK_RAW, | |
protocol); |
udp6_socket =
socket( |
AF_INET6, |
| SOCK_DGRAM, | |
protocol); |
Linux 2.2 optionally implements the Internet Protocol, version 6. This man page contains a description of the IPv6 basic API as implemented by the Linux kernel and glibc 2.1. The interface is based on the BSD sockets interface; see socket(7).
The IPv6 API aims to be mostly compatible with the IPv4 API (see ip(7)). Only differences are described in this man page.
To bind an AF_INET6 socket to any process,
the local address should be copied from the in6addr_any variable which
has in6_addr type.
In static initializations, IN6ADDR_ANY_INIT may also be used, which
expands to a constant expression. Both of them are in network
byte order.
The IPv6 loopback address (::1) is available in the global
in6addr_loopback
variable. For initializations, IN6ADDR_LOOPBACK_INIT should be used.
IPv4 connections can be handled with the v6 API by using the v4-mapped-on-v6 address type; thus a program needs to support only this API type to support both protocols. This is handled transparently by the address handling functions in the C library.
IPv4 and IPv6 share the local port space. When you get an IPv4 connection or packet to a IPv6 socket, its source address will be mapped to v6 and it will be mapped to v6.
struct sockaddr_in6 { sa_family_t sin6_family;in_port_t sin6_port;uint32_t sin6_flowinfo;struct in6_addr sin6_addr;uint32_t sin6_scope_id;}; struct in6_addr { unsigned char s6_addr[16];};
sin6_family is
always set to AF_INET6; sin6_port is the protocol
port (see sin_port in ip(7)); sin6_flowinfo is the IPv6
flow identifier; sin6_addr is the 128-bit IPv6
address. sin6_scope_id is an ID
depending on the scope of the address. It is new in Linux
2.4. Linux supports it only for link-local addresses, in
that case sin6_scope_id contains the
interface index (see netdevice(7))
IPv6 supports several address types: unicast to address a single host, multicast to address a group of hosts, anycast to address the nearest member of a group of hosts (not implemented in Linux), IPv4-on-IPv6 to address a IPv4 host, and other reserved address types.
The address notation for IPv6 is a group of 8 4-digit hexadecimal numbers, separated with a ':'. "::" stands for a string of 0 bits. Special addresses are ::1 for loopback and ::FFFF:<IPv4 address> for IPv4-mapped-on-IPv6.
The port space of IPv6 is shared with IPv4.
IPv6 supports some protocol-specific socket options that
can be set with setsockopt(2) and read
with getsockopt(2). The socket
option level for IPv6 is IPPROTO_IPV6. A boolean integer flag is
zero when it is false, otherwise true.
IPV6_ADDRFORMTurn an AF_INET6 socket into a
socket of a different address family. Only
AF_INET is currently
supported for that. It is allowed only for IPv6
sockets that are connected and bound to a
v4-mapped-on-v6 address. The argument is a pointer to
an integer containing AF_INET. This is useful to pass
v4-mapped sockets as file descriptors to programs
that don't know how to deal with the IPv6 API.
Control membership in multicast groups. Argument is a pointer to a struct ipv6_mreq.
IPV6_MTUgetsockopt():
Retrieve the current known path MTU of the current
socket. Only valid when the socket has been
connected. Returns an integer.
setsockopt(): Set
the MTU to be used for the socket. The MTU is limited
by the device MTU or the path MTU when path MTU
discovery is enabled. Argument is a pointer to
integer.
IPV6_MTU_DISCOVERControl path-MTU discovery on the socket. See
IP_MTU_DISCOVER in
ip(7) for
details.
IPV6_MULTICAST_HOPSSet the multicast hop limit for the socket. Argument is a pointer to an integer. −1 in the value means use the route default, otherwise it should be between 0 and 255.
IPV6_MULTICAST_IFSet the device for outgoing multicast packets on
the socket. This is allowed only for SOCK_DGRAM and
SOCK_RAW
socket. The argument is a pointer to an interface
index (see netdevice(7)) in an
integer.
IPV6_MULTICAST_LOOPControl whether the socket sees multicast packets that it has send itself. Argument is a pointer to boolean.
IPV6_RECVPKTINFO (since Linux
2.6.14)Set delivery of the IPV6_PKTINFO control message on
incoming datagrams. Such control messages contain a
struct
in6_pktinfo, as per RFC 3542. Only
allowed for SOCK_DGRAM or
SOCK_RAW
sockets. Argument is a pointer to a boolean value in
an integer.
Set delivery of control messages for incoming
datagrams containing extension headers from the
received packet. IPV6_RTHDR delivers the routing
header, IPV6_AUTHHDR
delivers the authentication header, IPV6_DSTOPTS delivers the
destination options, IPV6_HOPOPTS delivers the hop
options, IPV6_FLOWINFO
delivers an integer containing the flow ID,
IPV6_HOPLIMIT delivers
an integer containing the hop count of the packet.
The control messages have the same type as the socket
option. All these header options can also be set for
outgoing packets by putting the appropriate control
message into the control buffer of sendmsg(2). Only
allowed for SOCK_DGRAM or
SOCK_RAW
sockets. Argument is a pointer to a boolean
value.
IPV6_RECVERRControl receiving of asynchronous error options.
See IP_RECVERR in
ip(7) for details.
Argument is a pointer to boolean.
IPV6_ROUTER_ALERTPass forwarded packets containing a router alert
hop-by-hop option to this socket. Only allowed for
SOCK_RAW
sockets. The tapped packets are not forwarded by the
kernel, it is the user's responsibility to send them
out again. Argument is a pointer to an integer. A
positive integer indicates a router alert option
value to intercept. Packets carrying a router alert
option with a value field containing this integer
will be delivered to the socket. A negative integer
disables delivery of packets with router alert
options to this socket.
IPV6_UNICAST_HOPSSet the unicast hop limit for the socket. Argument is a pointer to an integer. −1 in the value means use the route default, otherwise it should be between 0 and 255.
IPV6_V6ONLY (since Linux 2.4.21 and
2.6)If this flag is set to true (nonzero), then the socket is restricted to sending and receiving IPv6 packets only. In this case, an IPv4 and an IPv6 application can bind to a single port at the same time.
If this flag is set to false (zero), then the socket can be used to send and receive packets to and from an IPv6 address or an IPv4-mapped IPv6 address.
The argument is a pointer to a boolean value in an integer.
The default value for this flag is defined by the
contents of the file /proc/sys/net/ipv6/bindv6only. The
default value for that file is 0 (false).
The user tried to bind(2) to a
link-local IPv6 address, but the sin6_scope_id in the
supplied sockaddr_in6 structure
is not a valid interface index.
Linux 2.4 will break binary compatibility for the
sockaddr_in6 for
64-bit hosts by changing the alignment of in6_addr and adding an
additional sin6_scope_id field. The kernel
interfaces stay compatible, but a program including
sockaddr_in6 or
in6_addr into other
structures may not be. This is not a problem for 32-bit hosts
like i386.
The sin6_flowinfo
field is new in Linux 2.4. It is transparently passed/read by
the kernel when the passed address length contains it. Some
programs that pass a longer address buffer and then check the
outgoing address length may break.
The sockaddr_in6
structure is bigger than the generic sockaddr. Programs that
assume that all address types can be stored safely in a
struct sockaddr need
to be changed to use struct
sockaddr_storage for that instead.
SOL_IP, SOL_IPV6, SOL_ICMPV6 and other SOL_* socket options are nonportable
variants of IPPROTO_*. See also
ip(7).
The IPv6 extended API as in RFC 2292 is currently only partly implemented; although the 2.2 kernel has near complete support for receiving options, the macros for generating IPv6 options are missing in glibc 2.1.
IPSec support for EH and AH headers is missing.
Flow label management is not complete and not documented here.
This man page is not complete.
RFC 2553: IPv6 BASIC API; Linux tries to be compliant to this. RFC 2460: IPv6 specification.
This page is part of release 4.07 of the Linux man-pages project. A
description of the project, information about reporting bugs,
and the latest version of this page, can be found at
https://www.kernel.org/doc/man−pages/.
|
This man page is Copyright (C) 2000 Andi Kleen <akmuc.de>. %%%LICENSE_START(VERBATIM_ONE_PARA) Permission is granted to distribute possibly modified copies of this page provided the header is included verbatim, and in case of nontrivial modification author and date of the modification is added to the header. %%%LICENSE_END $Id: ipv6.7,v 1.3 2000/12/20 18:10:31 ak Exp $ The following socket options are undocumented All of the following are from: commit 333fad5364d6b457c8d837f7d05802d2aaf8a961 Author: YOSHIFUJI Hideaki <yoshfujilinux-ipv6.org> Support several new sockopt / ancillary data in Advanced API (RFC3542). IPV6_2292PKTINFO (2.6.14) Formerly IPV6_PKTINFO IPV6_2292HOPOPTS (2.6.14) Formerly IPV6_HOPOPTS, which is documented IPV6_2292DSTOPTS (2.6.14) Formerly IPV6_DSTOPTS, which is documented IPV6_2292RTHDR (2.6.14) Formerly IPV6_RTHDR, which is documented IPV6_2292PKTOPTIONS (2.6.14) Formerly IPV6_PKTOPTIONS IPV6_2292HOPLIMIT (2.6.14) Formerly IPV6_HOPLIMIT, which is documented IPV6_RECVHOPLIMIT (2.6.14) IPV6_RECVHOPOPTS (2.6.14) IPV6_RTHDRDSTOPTS (2.6.14) IPV6_RECVRTHDR (2.6.14) IPV6_RECVDSTOPTS (2.6.14) IPV6_RECVPATHMTU (2.6.35, flag value added in 2.6.14) commit 793b14731686595a741d9f47726ad8b9a235385a Author: Brian Haley <brian.haleyhp.com> IPV6_PATHMTU (2.6.35, flag value added in 2.6.14) commit 793b14731686595a741d9f47726ad8b9a235385a Author: Brian Haley <brian.haleyhp.com> IPV6_DONTFRAG (2.6.35, flag value added in 2.6.14) commit 793b14731686595a741d9f47726ad8b9a235385a Author: Brian Haley <brian.haleyhp.com> commit 4b340ae20d0e2366792abe70f46629e576adaf5e Author: Brian Haley <brian.haleyhp.com> IPV6_RECVTCLASS (2.6.14) commit 41a1f8ea4fbfcdc4232f023732584aae2220de31 Author: YOSHIFUJI Hideaki <yoshfujilinux-ipv6.org> Based on patch from David L Stevens <dlstevensus.ibm.com> IPV6_CHECKSUM (2.2) IPV6_NEXTHOP (2.2) IPV6_JOIN_ANYCAST (2.4.21 / 2.6) IPV6_LEAVE_ANYCAST (2.4.21 / 2.6) IPV6_FLOWLABEL_MGR (2.2.7 / 2.4) IPV6_FLOWINFO_SEND (2.2.7 / 2.4) IPV6_IPSEC_POLICY (2.6) IPV6_XFRM_POLICY (2.6) IPV6_TCLASS (2.6) IPV6_ADDR_PREFERENCES (2.6.26) commit 7cbca67c073263c179f605bdbbdc565ab29d801d Author: YOSHIFUJI Hideaki <yoshfujilinux-ipv6.org> IPV6_MINHOPCOUNT (2.6.35) commit e802af9cabb011f09b9c19a82faef3dd315f27eb Author: Stephen Hemminger <shemmingervyatta.com> IPV6_ORIGDSTADDR (2.6.37) Actually a CMSG rather than a sockopt? In header file, we have IPV6_RECVORIGDSTADDR == IPV6_ORIGDSTADDR commit 6c46862280c5f55eda7750391bc65cd7e08c7535 Author: Balazs Scheidler <bazsibalabit.hu> IPV6_RECVORIGDSTADDR (2.6.37) commit 6c46862280c5f55eda7750391bc65cd7e08c7535 Author: Balazs Scheidler <bazsibalabit.hu> Support for IPV6_RECVORIGDSTADDR sockopt for UDP sockets were contributed by Harry Mason. IPV6_TRANSPARENT (2.6.37) commit 6c46862280c5f55eda7750391bc65cd7e08c7535 Author: Balazs Scheidler <bazsibalabit.hu> IPV6_UNICAST_IF (3.4) commit c4062dfc425e94290ac427a98d6b4721dd2bc91f Author: Erich E. Hoover <ehoovermines.edu> |