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NAME

       address_families - socket address families (domains)

SYNOPSIS

       #include <sys/types.h>          /* See NOTES */
       #include <sys/socket.h>

       int socket(int domain, int type, int protocol);

DESCRIPTION

       The  domain  argument  of the socket(2) specifies a communication domain; this selects the
       protocol family which will be used for  communication.   These  families  are  defined  in
       <sys/socket.h>.  The formats currently understood by the Linux kernel include:

       AF_UNIX, AF_LOCAL
              Local communication For further information, see unix(7).

       AF_INET
              IPv4 Internet protocols.  For further information, see ip(7).

       AF_AX25
              Amateur radio AX.25 protocol.  For further information, see ax25(4).

       AF_IPX IPX - Novell protocols.

       AF_APPLETALK
              AppleTalk For further information, see ddp(7).

       AF_NETROM
              AX.25  packet  layer  protocol.  For further information, see netrom(4), The Packet
              Radio Protocols and Linux ⟨https://www.tldp.org/HOWTO/AX25-HOWTO/x61.html⟩ and  the
              AX.25,  NET/ROM,  and  ROSE network programming chapters of the Linux Amateur Radio
              AX.25 HOWTO ⟨https://www.tldp.org/HOWTO/AX25-HOWTO/x2107.html⟩.

       AF_BRIDGE
              Can't be used for creating sockets; mostly used for bridge  links  in  rtnetlink(7)
              protocol commands.

       AF_ATMPVC
              Access  to raw ATM Permanent Virtual Circuits (PVCs).  For further information, see
              the ATM on Linux HOWTO ⟨https://www.tldp.org/HOWTO/text/ATM-Linux-HOWTO⟩.

       AF_X25 ITU-T X.25 / ISO-8208 protocol.  For further information, see x25(7).

       AF_INET6
              IPv6 Internet protocols.  For further information, see ipv6(7).

       AF_ROSE
              RATS (Radio Amateur Telecommunications Society)  Open  Systems  environment  (ROSE)
              AX.25 packet layer protocol.  For further information, see the resources listed for
              AF_NETROM.

       AF_DECnet
              DECet protocol  sockets.   See  Documentation/networking/decnet.txt  in  the  Linux
              kernel source tree for details.

       AF_NETBEUI
              Reserved for "802.2LLC project"; never used.

       AF_SECURITY
              This  was  a  short-lived (between Linux 2.1.30 and 2.1.99pre2) protocol family for
              firewall upcalls.

       AF_KEY Key management protocol, originally developed for usage  with  IPsec  (since  Linux
              2.1.38).  This has no relation to keyctl(2) and the in-kernel key storage facility.
              See     RFC     2367     PF_KEY     Key     Management     API,      Version      2
              ⟨https://tools.ietf.org/html/rfc2367⟩ for details.

       AF_NETLINK
              Kernel user interface device For further information, see netlink(7).

       AF_PACKET
              Low-level packet interface.  For further information, see packet(7).

       AF_ECONET
              Acorn  Econet  protocol  (removed  in  Linux  3.5).   See  the Econet documentation
              ⟨http://www.8bs.com/othrdnld/manuals/econet.shtml⟩ for details.

       AF_ATMSVC
              Access to ATM  Switched  Virtual  Circuits  (SVCs)  See  the  ATM  on  Linux  HOWTO
              ⟨https://www.tldp.org/HOWTO/text/ATM-Linux-HOWTO⟩ for details.

       AF_RDS Reliable  Datagram  Sockets (RDS) protocol (since Linux 2.6.30).  RDS over RDMA has
              no relation to AF_SMC or AF_XDP.  For further information see rds(7),  rds-rdma(7),
              and Documentation/networking/rds.txt in the Linux kernel source tree.

       AF_IRDA
              Socket interface over IrDA (moved to staging in Linux 4.14, removed in Linux 4.17).
              For further information see irda(7).

       AF_PPPOX
              Generic PPP transport layer, for setting up  L2  tunnels  (L2TP  and  PPPoE).   See
              Documentation/networking/l2tp.txt in the Linux kernel source tree for details.

       AF_WANPIPE
              Legacy  protocol  for wide area network (WAN) connectivity that was used by Sangoma
              WAN cards (called "WANPIPE"); removed in Linux 2.6.21.

       AF_LLC Logical link control (IEEE 802.2 LLC) protocol, upper part of data  link  layer  of
              ISO/OSI  networking protocol stack (since Linux 2.4); has no relation to AF_PACKET.
              See chapter 13.5.3. Logical Link Control in Understanding  Linux  Kernel  Internals
              (O'Reilly  Media,  2006)  and  IEEE Standards for Local Area Networks: Logical Link
              Control (The Institute of Electronics and Electronics Engineers,  Inc.,  New  York,
              New    York,    1985)    for    details.     See   also   some   historical   notes
              ⟨https://wiki.linuxfoundation.org/networking/llc⟩ regarding its development.

       AF_IB  InfiniBand native addressing (since Linux 3.11).

       AF_MPLS
              Multiprotocol Label Switching (since Linux 4.1); mostly used for  configuring  MPLS
              routing  via  netlink(7),  as  it  doesn't expose ability to create sockets to user
              space.

       AF_CAN Controller  Area  Network  automotive  bus  protocol  (since  Linux  2.6.25).   See
              Documentation/networking/can.rst in the Linux kernel source tree for details.

       AF_TIPC
              TIPC,   "cluster   domain   sockets"  protocol  (since  Linux  2.6.16).   See  TIPC
              Programmer's Guidehttp://tipc.io/programming.html⟩ and the  protocol  description
              ⟨http://tipc.io/protocol.html⟩ for details.

       AF_BLUETOOTH
              Bluetooth  low-level  socket protocol (since Linux 3.11).  See Bluetooth Management
              API   overview   ⟨https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/doc/mgmt-
              api.txt⟩   and   An   Introduction   to   Bluetooth  Programming  by  Albert  Huang
              ⟨https://people.csail.mit.edu/albert/bluez-intro/⟩ for details.

       AF_IUCV
              IUCV  (inter-user  communication  vehicle)  z/VM  protocol   for   hypervisor-guest
              interaction  (since  Linux  2.6.21);  has no relation to AF_VSOCK and/or AF_SMC See
              IUCV protocol overview ⟨https://www.ibm.com/support/knowledgecenter/en/SSB27U_6.4.0
              /com.ibm.zvm.v640.hcpb4/iucv.htm⟩ for details.
       AF_RXRPC
              Rx,  Andrew  File  System remote procedure call protocol (since Linux 2.6.22).  See
              Documentation/networking/rxrpc.txt in the Linux kernel source tree for details.

       AF_ISDN
              New "modular ISDN" driver interface protocol (since Linux 2.6.27).  See  the  mISDN
              wiki ⟨http://www.misdn.eu/wiki/Main_Page/⟩ for details.

       AF_PHONET
              Nokia    cellular    modem   IPC/RPC   interface   (since   Linux   2.6.31).    See
              Documentation/networking/phonet.txt in the Linux kernel source tree for details.

       AF_IEEE802154
              IEEE 802.15.4 WPAN (wireless personal area  network)  raw  packet  protocol  (since
              Linux  2.6.31).   See  Documentation/networking/ieee802154.txt  in the Linux kernel
              source tree for details.

       AF_CAIF
              Ericsson's Communication CPU to Application CPU interface  (CAIF)  protocol  (since
              Linux  2.6.36).   See  Documentation/networking/caif/Linux-CAIF.txt  in  the  Linux
              kernel source tree for details.

       AF_ALG Interface    to    kernel    crypto    API    (since    Linux     2.6.38).      See
              Documentation/crypto/userspace-if.rst in the Linux kernel source tree for details.

       AF_VSOCK
              VMWare VSockets protocol for hypervisor-guest interaction (since Linux 3.9); has no
              relation to AF_IUCV and AF_SMC.  For further information, see vsock(7).

       AF_KCM KCM  (kernel  connection   multiplexor)   interface   (since   Linux   4.6).    See
              Documentation/networking/kcm.txt in the Linux kernel source tree for details.

       AF_QIPCRTR
              Qualcomm IPC router interface protocol (since Linux 4.7).

       AF_SMC SMC-R  (shared  memory  communications  over RDMA) protocol (since Linux 4.11), and
              SMC-D (shared memory communications, direct memory access) protocol for  intra-node
              z/VM  quest  interaction  (since Linux 4.19); has no relation to AF_RDS, AF_IUCV or
              AF_VSOCK.  See RFC 7609  IBM's  Shared  Memory  Communications  over  RDMA  (SMC-R)
              Protocol  ⟨https://tools.ietf.org/html/rfc7609⟩  for  details regarding SMC-R.  See
              SMC-D  Reference  Information   ⟨https://www-01.ibm.com/software/network/commserver
              /SMC-D/index.html⟩ for details regarding SMC-D.

       AF_XDP XDP     (express    data    path)    interface    (since    Linux    4.18).     See
              Documentation/networking/af_xdp.rst in the Linux kernel source tree for details.

SEE ALSO

       socket(2), socket(7)

COLOPHON

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