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udp (4)
  • >> udp (4) ( FreeBSD man: Специальные файлы /dev/* )
  • udp (4) ( Linux man: Специальные файлы /dev/* )
  • udp (7) ( Solaris man: Макропакеты и соглашения )
  • udp (7) ( Русские man: Макропакеты и соглашения )
  • udp (7) ( Linux man: Макропакеты и соглашения )
  • Ключ udp обнаружен в базе ключевых слов.

  • BSD mandoc
     

    NAME

    
    
    udp
    
     - Internet User Datagram Protocol
    
     
    

    SYNOPSIS

       #include <sys/types.h>
       #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(2) and recvfrom(2) 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    #include <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).  

    ERRORS

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

    Bq Er 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;
    Bq Er ENOTCONN
    when trying to send a datagram, but no destination address is specified, and the socket has not been connected;
    Bq Er ENOBUFS
    when the system runs out of memory for an internal data structure;
    Bq Er EADDRINUSE
    when an attempt is made to create a socket with a port which has already been allocated;
    Bq Er EADDRNOTAVAIL
    when an attempt is made to create a socket with a network address for which no network interface exists.

     

    MIB VARIABLES

    The protocol implements a number of variables in the net.inet branch of the sysctl(3) MIB.

    UDPCTL_CHECKSUM
    (udp.checksum) Enable udp checksums (enabled by default).
    UDPCTL_MAXDGRAM
    (udp.maxdgram) Maximum outgoing UDP datagram size
    UDPCTL_RECVSPACE
    (udp.recvspace) Maximum space for incoming UDP datagrams
    udp.log_in_vain
    For all udp datagrams, to ports on which there is no socket listening, log the connection attempt (disabled by default).
    udp.blackhole
    When a datagram is received on a port where there is no socket listening, do not return an ICMP port unreachable message. (Disabled by default. See blackhole(4).)

     

    SEE ALSO

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

    HISTORY

    The protocol appeared in BSD 4.2


     

    Index

    NAME
    SYNOPSIS
    DESCRIPTION
    ERRORS
    MIB VARIABLES
    SEE ALSO
    HISTORY


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