ADDRESS_FAMILIES

Section: Linux Programmer's Manual (7)
Updated: 2021-03-22
Index Return to Main Contents

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 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) protocol 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-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 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 details.
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 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 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 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 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 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 multiplexer) 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 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/networking/af_xdp.rst in the Linux kernel source tree for details.

COLOPHON

This page is part of release 5.11 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/.