UDP(4N)                 COMMAND REFERENCE                 UDP(4N)



NAME
     udp - Internet User Datagram Protocol

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

     s = socket(AFINET, SOCKDGRAM, 0);

DESCRIPTION
     UDP is a simple, unreliable datagram protocol which 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 calls, though the
     connect(2) call may also be used to fix the destination for
     future packets (in which case the recv(2) or read(2) and
     send(2) or write(2) system calls 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 (i.e. a UDP port
     may not be "connected" to a TCP port).  In addition
     broadcast packets may be sent (assuming the underlying
     network supports this) by using a reserved "broadcast
     address"; this address is network interface dependent.

DIAGNOSTICS
     A socket operation may fail with one of the following errors
     returned:

     [EISCONN]
         when trying to establish a connection on a socket which
         already has one, or when trying to send a datagram with
         the destination address specified and the socket is
         already connected;

     [ENOTCONN]
         when trying to send a datagram, but no destination
         address is specified, and the socket hasn't been
         connected;

     [ENOBUFS]
         when the system runs out of memory for an internal data
         structure;

     [EADDRINUSE]
         when an attempt is made to create a socket with a port
         which has already been allocated;

     [EADDRNOTAVAIL]
         when an attempt is made to create a socket with a



Printed 10/17/86                                                1

UDP(4N)                 COMMAND REFERENCE                 UDP(4N)



         network address for which no network interface exists.

SEE ALSO
     send(2), recv(2), inet(4n), intro(4n).



















































Printed 10/17/86                                                2

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