udp(7) [osf1 man page]

udp(7)							 Miscellaneous Information Manual						    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.  There is no broadcast address in IPv6.

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

ERRORS

       If a socket operation fails, errno may be set to one of the following values: An attempt was made to create a socket with a port  that  has
       already	been  allocated.  An attempt was made to create a socket with a network address for which no network interface exists.	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  desti-
       nation  address	specified.   The  system  ran out of memory for an internal data structure.  The destination address of a datagram was not
       specified, and the socket has not been connected.

RELATED INFORMATION

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

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

																	    udp(7)

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UDP(4)							   BSD Kernel Interfaces Manual 						    UDP(4)

NAME

     udp -- Internet User Datagram Protocol

SYNOPSIS

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

     int
     socket(AF_INET, SOCK_DGRAM, 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.

     Options at the IP transport level may be used with UDP; see ip(4).

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 destina-
		      tion 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 network address for which no network interface exists.

SEE ALSO

     getsockopt(2), recv(2), send(2), socket(2), intro(4), inet(4), ip(4)

HISTORY

     The udp protocol appeared in 4.2BSD.

4.2 Berkeley Distribution					   June 5, 1993 					 4.2 Berkeley Distribution

Linux and UNIX Man Pages

udp(7) [osf1 man page]

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