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VSOCK(7)                   Linux Programmer's ManualVSOCK(7)NAME       vsock - Linux VSOCK address familySYNOPSIS       #include <sys/socket.h>       #include <linux/vm_sockets.h>       stream_socket = socket(AF_VSOCK, SOCK_STREAM, 0);       datagram_socket = socket(AF_VSOCK, SOCK_DGRAM, 0);DESCRIPTION       The  VSOCK address family facilitates communication between virtual ma-       chines and the host they are running on.  This address family  is  used       by  guest  agents  and  hypervisor  services that need a communications       channel that is independent of virtual machine network configuration.       Valid socket types are SOCK_STREAM and  SOCK_DGRAM.   SOCK_STREAM  pro-       vides connection-oriented byte streams with guaranteed, in-order deliv-       ery.  SOCK_DGRAM provides a connectionless datagram packet service with       best-effort  delivery  and best-effort ordering.  Availability of these       socket types is dependent on the underlying hypervisor.       A new socket is created with           socket(AF_VSOCK, socket_type, 0);       When a process wants to establish a  connection,  it  callsconnect(2)       with  a  given destination socket address.  The socket is automatically       bound to a free port if unbound.       A process can listen for incoming connections by  first  binding  to  a       socket address usingbind(2) and then callinglisten(2).       Data  is  transmitted  using thesend(2) orwrite(2) families of system       calls and data is received using therecv(2)  orread(2)  families  of       system calls.   Address format       A  socket address is defined as a combination of a 32-bit Context Iden-       tifier (CID) and a 32-bit port number.  The CID identifies  the  source       or  destination,  which  is  either a virtual machine or the host.  The       port number differentiates between multiple services running on a  sin-       gle machine.           struct sockaddr_vm {               sa_family_t    svm_family;     /* Address family: AF_VSOCK */               unsigned short svm_reserved1;               unsigned int   svm_port;       /* Port # in host byte order */               unsigned int   svm_cid;        /* Address in host byte order */               unsigned char  svm_zero[sizeof(struct sockaddr) -                                       sizeof(sa_family_t) -                                       sizeof(unsigned short) -                                       sizeof(unsigned int) -                                       sizeof(unsigned int)];           };       svm_family  is  always set to AF_VSOCK.  svm_reserved1 is always set to       0.  svm_port contains the port number in host  byte  order.   The  port       numbers  below  1024  are called privileged ports.  Only a process with       the CAP_NET_BIND_SERVICE capability maybind(2) to these port  numbers.       svm_zero must be zero-filled.       There are several special addresses: VMADDR_CID_ANY (-1U) means any ad-       dress for binding; VMADDR_CID_HYPERVISOR (0) is reserved  for  services       built  into  the  hypervisor; VMADDR_CID_RESERVED (1) must not be used;       VMADDR_CID_HOST (2) is the well-known address of the host.       The special constant VMADDR_PORT_ANY (-1U) means any  port  number  for       binding.   Live migration       Sockets  are affected by live migration of virtual machines.  Connected       SOCK_STREAM sockets become disconnected when the  virtual  machine  mi-       grates to a new host.  Applications must reconnect when this happens.       The  local  CID  may change across live migration if the old CID is not       available on the new host.  Bound sockets are automatically updated  to       the new CID.   Ioctls       IOCTL_VM_SOCKETS_GET_LOCAL_CID              Get  the CID of the local machine.  The argument is a pointer to              an unsigned int.                  ioctl(socket, IOCTL_VM_SOCKETS_GET_LOCAL_CID, &cid);              Consider using VMADDR_CID_ANY when binding  instead  of  getting              the local CID with IOCTL_VM_SOCKETS_GET_LOCAL_CID.ERRORS       EACCES Unable    to   bind   to   a   privileged   port   without   the              CAP_NET_BIND_SERVICE capability.       EADDRINUSE              Unable to bind to a port that is already in use.       EADDRNOTAVAIL              Unable to find a free port for binding or unable to  bind  to  a              nonlocal CID.       EINVAL Invalid  parameters.  This includes: attempting to bind a socket              that is already bound, providing an invalid struct  sockaddr_vm,              and other input validation errors.       ENOPROTOOPT              Invalid socket option insetsockopt(2) orgetsockopt(2).       ENOTCONN              Unable to perform operation on an unconnected socket.       EOPNOTSUPP              Operation  not  supported.  This includes: the MSG_OOB flag that              is not implemented  for  thesend(2)  family  of  syscalls  and              MSG_PEEK for therecv(2) family of syscalls.       EPROTONOSUPPORT              Invalid  socket  protocol number.  The protocol should always be              0.       ESOCKTNOSUPPORT              Unsupported socket type  insocket(2).   Only  SOCK_STREAM  and              SOCK_DGRAM are valid.VERSIONS       Support  for  VMware  (VMCI)  has  been available since Linux 3.9.  KVM       (virtio) is supported since Linux  4.8.   Hyper-V  is  supported  since       Linux 4.14.SEE ALSObind(2),connect(2),listen(2),recv(2),send(2),socket(2), capabili-ties(7)COLOPHON       This page is part of release 5.05 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                             2020-02-09VSOCK(7)