man > address_families(7)

address_families(7)               Miscellaneous Information Manual               address_families(7)

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 pro‐
       tocol  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  and  the AX.25, NET/ROM, and ROSE network programming chapters of
              the Linux Amateur Radio AX.25 HOWTO.

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

       AF_ATMPVC
              Access to raw ATM Permanent Virtual Circuits (PVCs).  For further information, see the
              ATM on Linux HOWTO.

       AF_X25 ITU-T X.25 / ISO/IEC 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 fire‐
              wall 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 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  for  de‐
              tails.

       AF_ATMSVC
              Access to ATM Switched Virtual Circuits (SVCs) See the ATM on 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 Documen‐
              tation/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  Con‐
              trol  (The  Institute  of  Electronics  and Electronics Engineers, Inc., New York, New
              York, 1985) for details.  See also some historical notes 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 Documenta‐
              tion/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
              Guide and the protocol description for details.

       AF_BLUETOOTH
              Bluetooth  low-level socket protocol (since Linux 3.11).  See Bluetooth Management API
              overview and An Introduction to Bluetooth Programming by Albert Huang 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 for details.

       AF_RXRPC
              Rx, Andrew File System remote procedure call protocol (since Linux 2.6.22).  See Docu‐
              mentation/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
              for details.

       AF_PHONET
              Nokia  cellular  modem IPC/RPC interface (since Linux 2.6.31).  See Documentation/net‐
              working/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/user‐
              space-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  multiplexer)  interface  (since  Linux 4.6).  See Documenta‐
              tion/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 for details
              regarding SMC-R.  See SMC-D Reference Information for details regarding SMC-D.

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

SEE ALSO
       socket(2), socket(7)

Linux man-pages 6.7                          2024-01-28                          address_families(7)