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intro(3n) [ultrix man page]

intro(3n)																 intro(3n)

Name
       intro - introduction to network library functions

Description
       This  section describes functions that are available for interprocess communication (IPC).  IPC takes place using sockets.  The system call
       creates a communications channel based on domain, type, and protocol.

       Sockets are created without names.  The system call is used to connect a name to a socket.

       A connection with another process must be made before data can be transferred on a bound socket.  The system call  is  used  to	rendezvous
       with another process.  This process must be listening on a bound socket using the system call.  This listening process can accept a connec-
       tion request using the system call.

       Once two processes have connected and accepted an IPC, data can be transferred with the following system calls: and

       Connectionless sockets are also possible (a socket is bound and data can be transferred).  They use the following system calls to  transfer
       data: and

       IPC operates in three domains:

       UNIX		Local node

       INTERNET 	Local area network (LAN)

       DECNET		DECnet network

       These types of sockets are available for IPC:

       stream		Sequenced, reliable, unduplicated data
			CONNECTED socket
			record boundaries not preserved
			all domains

       datagram 	Not guaranteed to be sequenced, reliable, or
			unduplicated
			user protocol needed to give guarantees
			UNCONNECTED socket
			record boundaries preserved
			UNIX and INTERNET domains

       sequenced packet Like stream socket, except record boundaries preserved
			DECNET domain only

       raw		Access to communications protocols

Internet Addresses Routines
       The inet routines manipulate Internet addresses.

Network Data Base File Routines
       Standard  mapping  routines are used to retrieve entries in network data base files.  Several routines operating on each data base file are
       identified by a group name:

       Retrieves entries from

       Retrieves entries from

       Retrieves entries from

       Retrieves entries from

       Specific routines perform particular operations on each data base file:

       Reads the next line of the file; opens
			the file, if necessary.

       Opens and rewinds the file.

       Closes the file.

       Searches the file sequentially from the beginning
			until a matching name is found, or EOF is encountered.

       Searches the file sequentially from the beginning
			until a matching address is found, or EOF is encountered.

       Searches the file sequentially from the beginning
			until a matching port number is found, or EOF is encountered.

       Searches the file sequentially from the beginning
			until a matching protocol number is found, or EOF is encountered.

       Each network library routine returns a pointer to a structure reflecting individual fields of a line in one of the network data base files.
       The  structure  for each data base file contains some of the fields in the following list, with the prefix x replaced by a different letter
       in each file:

       pointer to a network address,
			returned in network-byte order

       address family of the address being returned

       alternate names

       length of an address, in bytes

       official name

       network number, returned in machine-byte order

       resident port

       protocol number

																	 intro(3n)

Check Out this Related Man Page

TCP(4P) 																   TCP(4P)

NAME
tcp - Internet Transmission Control Protocol SYNOPSIS
#include <sys/socket.h> #include <netinet/in.h> s = socket(AF_INET, SOCK_STREAM, 0); DESCRIPTION
The TCP protocol provides reliable, flow-controlled, two-way transmission of data. It is a byte-stream protocol used to support the SOCK_STREAM abstraction. TCP uses the standard Internet address format and, in addition, provides a per-host collection of "port addresses". Thus, each address is composed of an Internet address specifying the host and network, with a specific TCP port on the host identifying the peer entity. Sockets utilizing the tcp protocol are either "active" or "passive". Active sockets initiate connections to passive sockets. By default TCP sockets are created active; to create a passive socket the listen(2) system call must be used after binding the socket with the bind(2) system call. Only passive sockets may use the accept(2) call to accept incoming connections. Only active sockets may use the connect(2) call to initiate connections. Passive sockets may "underspecify" their location to match incoming connection requests from multiple networks. This technique, termed "wildcard addressing", allows a single server to provide service to clients on multiple networks. To create a socket which listens on all networks, the Internet address INADDR_ANY must be bound. The TCP port may still be specified at this time; if the port is not specified the system will assign one. Once a connection has been established the socket's address is fixed by the peer entity's location. The address assigned the socket is the address associated with the network interface through which packets are being transmitted and received. Normally this address corresponds to the peer entity's network. TCP supports one socket option which is set with setsockopt(2) and tested with getsockopt(2). Under most circumstances, TCP sends data when it is presented; when outstanding data has not yet been acknowledged, it gathers small amounts of output to be sent in a single packet once an acknowledgement is received. For a small number of clients, such as window systems that send a stream of mouse events which receive no replies, this packetization may cause significant delays. Therefore, TCP provides a boolean option, TCP_NODELAY (from <netinet/tcp.h>, to defeat this algorithm. The option level for the setsockopt call is the protocol number for TCP, available from getpro- tobyname(3N). Options at the IP transport level may be used with TCP; see ip(4P). Incoming connection requests that are source-routed are noted, and the reverse source route is used in responding. 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; [ENOBUFS] when the system runs out of memory for an internal data structure; [ETIMEDOUT] when a connection was dropped due to excessive retransmissions; [ECONNRESET] when the remote peer forces the connection to be closed; [ECONNREFUSED] when the remote peer actively refuses connection establishment (usually because no process is listening to the port); [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), socket(2), intro(4N), inet(4F), ip(4P) 4.2 Berkeley Distribution May 16, 1986 TCP(4P)
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