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udp(7)
NAME
  udp - Internet user datagram protocol (UDP)

SYNOPSIS
       #include <sys/socket.h>
       #include <netinet/in.h>

  The following is the socket call for AF_INET sockets:

       s = socket(AF_INET, SOCK_DGRAM, 0);

  The following is the socket call for AF_INET6 sockets:

       s = socket(AF_INET6, SOCK_DGRAM, 0);

DESCRIPTION
  UDP is a simple, unreliable datagram protocol that is used to support the
  SOCK_DGRAM abstraction for the Internet Protocol family.  UDP sockets are
  connectionless, and are normally used with the sendto() and recvfrom()
  functions, though the connect() function may also be used to fix the
  destination for future packets, in which case the recv() or read() and
  send() or write() functions may be used.

  UDP address formats are identical to those used by TCP.  In particular, UDP
  provides a port identifier in addition to the normal Internet address
  format.  Note that the UDP port space is separate from the TCP port space
  (that is, a UDP port may not be "connected" to a TCP port).  In addition,
  IPv4 broadcast packets may be sent (assuming the underlying network
  supports this) by using a reserved "broadcast address"; this address is
  network interface dependent.

				     Note

       There is no broadcast address in IPv6.

  Options at the IP transport level may be used with UDP; see the ip(7)
  reference page.

ERRORS
  If a socket operation fails, errno may be set to one of the following
  values:

  [EADDRINUSE]
      An attempt was made to create a socket with a port that has already
      been allocated.

  [EADDRNOTAVAIL]
      An attempt was made to create a socket with a network address for which
      no network interface exists.

  [EISCONN]
      The socket is already connected.	This error occurs when trying to
      establish connection on a socket or when trying to send a datagram with
      the destination address specified.

  [ENOBUFS]
      The system ran out of memory for an internal data structure.

  [ENOTCONN]
      The destination address of a datagram was not specified, and the socket
      has not been connected.

SEE ALSO
  Functions: getsockopt(2), recv(2), send(2), socket(2)

  Files: netintro(7), inet(7), ip(7)

Index for Section 7

Alphabetical listing for U

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