NAME<\/a> vsock \u2212 Linux VSOCK address family<\/p>\n #include stream_socket<\/i> = socket(AF_VSOCK, SOCK_STREAM, 0);<\/b> The VSOCK address family facilitates communication between virtual machines 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.<\/p>\n Valid socket types are SOCK_STREAM<\/b> and SOCK_DGRAM<\/b>. SOCK_STREAM<\/b> provides connection-oriented byte streams with guaranteed, in-order delivery. SOCK_DGRAM<\/b> 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.<\/p>\n A new socket is created with<\/p>\n socket(AF_VSOCK, socket_type, 0);<\/p>\n When a process wants to establish a connection, it calls connect<\/b>(2) with a given destination socket address. The socket is automatically bound to a free port if unbound.<\/p>\n A process can listen for incoming connections by first binding to a socket address using bind<\/b>(2) and then calling listen<\/b>(2).<\/p>\n Data is transmitted using the send<\/b>(2) or write<\/b>(2) families of system calls and data is received using the recv<\/b>(2) or read<\/b>(2) families of system calls.<\/p>\n Address format<\/b> struct sockaddr_vm { svm_family<\/i> is always set to AF_VSOCK<\/b>. svm_reserved1<\/i> is always set to 0. svm_port<\/i> contains the port number in host byte order. The port numbers below 1024 are called privileged ports<\/i>. Only a process with the CAP_NET_BIND_SERVICE<\/b> capability may bind<\/b>(2) to these port numbers. svm_zero<\/i> must be zero-filled.<\/p>\n There are several special addresses: VMADDR_CID_ANY<\/b> (\u22121U) means any address for binding; VMADDR_CID_HYPERVISOR<\/b> (0) is reserved for services built into the hypervisor; VMADDR_CID_LOCAL<\/b> (1) is the well-known address for local communication (loopback); VMADDR_CID_HOST<\/b> (2) is the well-known address of the host.<\/p>\n The special constant VMADDR_PORT_ANY<\/b> (\u22121U) means any port number for binding.<\/p>\n Live migration<\/b> 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.<\/p>\n Ioctls Get the CID of the local machine. The argument is a pointer to an unsigned int<\/i>.<\/p>\n ioctl(socket, IOCTL_VM_SOCKETS_GET_LOCAL_CID, &cid);<\/p>\n Consider using VMADDR_CID_ANY<\/b> when binding instead of getting the local CID with IOCTL_VM_SOCKETS_GET_LOCAL_CID<\/b>.<\/p>\n Local communication The local CID obtained with IOCTL_VM_SOCKETS_GET_LOCAL_CID<\/b> can be used for the same purpose, but it is preferable to use VMADDR_CID_LOCAL .<\/b><\/p>\n EACCES<\/b><\/p>\n<\/td>\n Unable to bind to a privileged port without the CAP_NET_BIND_SERVICE<\/b> capability.<\/p>\n<\/td>\n<\/tr>\n<\/table>\n EADDRINUSE<\/b><\/p>\n Unable to bind to a port that is already in use.<\/p>\n EADDRNOTAVAIL<\/b><\/p>\n Unable to find a free port for binding or unable to bind to a nonlocal CID.<\/p>\n EINVAL<\/b><\/p>\n<\/td>\n Invalid parameters. This includes: attempting to bind a socket that is already bound, providing an invalid struct sockaddr_vm<\/i>, and other input validation errors.<\/p>\n<\/td>\n<\/tr>\n<\/table>\n ENOPROTOOPT<\/b><\/p>\n Invalid socket option in setsockopt<\/b>(2) or getsockopt<\/b>(2).<\/p>\n ENOTCONN<\/b><\/p>\n Unable to perform operation on an unconnected socket.<\/p>\n EOPNOTSUPP<\/b><\/p>\n Operation not supported. This includes: the MSG_OOB<\/b> flag that is not implemented for the send<\/b>(2) family of syscalls and MSG_PEEK<\/b> for the recv<\/b>(2) family of syscalls.<\/p>\n EPROTONOSUPPORT<\/b><\/p>\n Invalid socket protocol number. The protocol should always be 0.<\/p>\n ESOCKTNOSUPPORT<\/b><\/p>\n Unsupported socket type in socket<\/b>(2). Only SOCK_STREAM<\/b> and SOCK_DGRAM<\/b> are valid.<\/p>\n 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.<\/p>\n VMADDR_CID_LOCAL is supported since Linux 5.6. Local communication in the guest and on the host is available since Linux 5.6. Previous versions supported only local communication within a guest (not on the host), and with only some transports (VMCI and virtio).<\/p>\n
SYNOPSIS<\/a>
DESCRIPTION<\/a>
ERRORS<\/a>
VERSIONS<\/a>
SEE ALSO<\/a>
COLOPHON<\/a> <\/p>\n
\nNAME <\/a> <\/h2>\n
SYNOPSIS <\/a> <\/h2>\n
#include
datagram_socket<\/i> = socket(AF_VSOCK, SOCK_DGRAM, 0);<\/b><\/p>\nDESCRIPTION <\/a> <\/h2>\n
A socket address is defined as a combination of a 32-bit Context Identifier (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 single machine.<\/p>\n
sa_family_t svm_family; \/bin \/boot \/dead.letter \/dev \/etc \/home \/initrd \/lib \/lib64 \/lost+found \/media \/mnt \/opt \/proc \/release-notes.html \/release-notes.txt \/root \/run \/sbin \/srv \/sys \/tmp \/usr \/var Address family: AF_VSOCK bodies\/ usr\/
unsigned short svm_reserved1;
unsigned int svm_port; \/bin \/boot \/dead.letter \/dev \/etc \/home \/initrd \/lib \/lib64 \/lost+found \/media \/mnt \/opt \/proc \/release-notes.html \/release-notes.txt \/root \/run \/sbin \/srv \/sys \/tmp \/usr \/var Port # in host byte order bodies\/ usr\/
unsigned int svm_cid; \/bin \/boot \/dead.letter \/dev \/etc \/home \/initrd \/lib \/lib64 \/lost+found \/media \/mnt \/opt \/proc \/release-notes.html \/release-notes.txt \/root \/run \/sbin \/srv \/sys \/tmp \/usr \/var Address in host byte order bodies\/ usr\/
unsigned char svm_zero[sizeof(struct sockaddr) \u2212
sizeof(sa_family_t) \u2212
sizeof(unsigned short) \u2212
sizeof(unsigned int) \u2212
sizeof(unsigned int)];
};<\/p>\n
Sockets are affected by live migration of virtual machines. Connected SOCK_STREAM<\/b> sockets become disconnected when the virtual machine migrates to a new host. Applications must reconnect when this happens.<\/p>\n
IOCTL_VM_SOCKETS_GET_LOCAL_CID<\/b><\/p>\n
VMADDR_CID_LOCAL<\/b> (1) directs packets to the same host that generated them. This is useful for testing applications on a single host and for debugging.<\/p>\nERRORS <\/a> <\/h2>\n
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\n <\/td>\n \n <\/td>\n \n VERSIONS <\/a> <\/h2>\n
SEE ALSO <\/a> <\/h2>\n