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ADDRESS_FAMILIES(7) Linux Programmer's 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
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 ker-
nel 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 Docu-
mentation/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 Documen-
tation/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 <http://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 interac-
tion (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 Documenta-
tion/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 ker-
nel source tree for details.
AF_ALG Interface to kernel crypto API (since Linux 2.6.38). See Documenta-
tion/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 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 <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/network-
ing/af_xdp.rst in the Linux kernel source tree for details.
SEE ALSO
socket(2), socket(7)
COLOPHON
This page is part of release 5.10 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/.
Linux 2018-10-16 ADDRESS_FAMILIES(7)
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