523 lines
14 KiB
HTML
523 lines
14 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>socket()--Create Socket</title>
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<!-- Begin Header Records ========================================== -->
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<!-- Unix8 SCRIPT J converted by B2H R4.1 (346) (CMS) by V2KEA304 -->
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<!-- at RCHVMW2 on 17 Feb 1999 at 11:05:09 -->
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<!-- End Header Records ============================================ -->
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<!-- Edited by Kersten Feb 02 -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<a name="Top_Of_Page"></a>
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<!--Java sync-link-->
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<script type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<h2>socket()--Create Socket</h2>
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<div class="box" style="width: 60%;">
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<br>
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Syntax
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<pre>
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#include <sys/types.h>
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#include <sys/socket.h>
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int socket(int <em>address_family</em>,
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int <em>type</em>,
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int <em>protocol</em>)
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</pre>
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<br>
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Service Program Name: QSOSRV1<br>
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<!-- iddvc RMBR -->
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: Yes<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <em>socket()</em> function is used to create an end point for
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communications. The end point is represented by the socket descriptor returned
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by the <em>socket()</em> function.</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong>address_family</strong></dt>
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<dd>(Input) The address family to be used with the socket. Supported values
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are:
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<table cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<td align="left" valign="top"><samp>AF_INET</samp></td>
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<td align="left" valign="top">For interprocess communications between processes
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on the same system or different systems in the Internet domain using the
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Internet Protocol (IPv4).</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>AF_INET6</samp></td>
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<td align="left" valign="top">For interprocess communications between processes
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on the same system or different systems in the Internet domain using the
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Internet Protocol (IPv6 or IPv4).</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>AF_NS</samp></td>
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<td align="left" valign="top">For interprocess communications between processes
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on the same system or different systems in the domain defined by the Novell or
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Xerox protocol definitions.
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<p> <strong>Note:</strong> The
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<samp>AF_NS</samp> address family is no longer supported as of V5R2.</p>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>AF_UNIX</samp></td>
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<td align="left" valign="top">For interprocess communications between processes
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on the same system in the UNIX domain.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>AF_UNIX_CCSID</samp></td>
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<td align="left" valign="top">For interprocess communications between processes
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on the same system in the UNIX domain using the Qlg_Path_Name_T structure.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>AF_TELEPHONY</samp></td>
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<td align="left" valign="top">For interprocess communications between processes
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on the same system in the telephony domain.
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<p><strong>Note:</strong> The
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<samp>AF_TELEPHONY</samp> address family is no longer supported as of V5R3.</p>
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</td>
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</tr>
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</table>
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</dd>
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<dt><strong>type</strong></dt>
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<dd>(Input) The type of communications desired. Supported values are:<br>
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<br>
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<table cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<td align="left" valign="top"><samp>SOCK_DGRAM</samp></td>
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<td align="left" valign="top">Indicates a datagram socket is desired.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>SOCK_SEQPACKET</samp></td>
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<td align="left" valign="top">Indicates a full-duplex sequenced packet socket
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is desired. Each input and output operation consists of exactly one
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record.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>SOCK_STREAM</samp></td>
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<td align="left" valign="top">Indicates a full-duplex stream socket is
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desired.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>SOCK_RAW</samp></td>
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<td align="left" valign="top">Indicates communication is directly to the
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network protocols. A process must have the appropriate privilege
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<samp>*ALLOBJ</samp> to use this type of socket. Used by users who want to
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access the lower-level protocols directly.</td>
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</tr>
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</table>
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<br>
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<br>
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</dd>
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<dt><strong>protocol</strong></dt>
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<dd>(Input) The protocol to be used on the socket. Supported values are:<br>
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<br>
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<table cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<td align="left" valign="top">0</td>
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<td align="left" valign="top">Indicates that the default protocol for the
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<em>type</em> selected is to be used. For example, <samp>IPPROTO_TCP</samp> is
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chosen for the protocol if the <em>type</em> was set to
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<samp>SOCK_STREAM</samp> and the address family is <samp>AF_INET</samp>.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>IPPROTO_IP</samp></td>
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<td align="left" valign="top">Equivalent to specifying the value zero (0).</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>IPPROTO_TCP</samp></td>
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<td align="left" valign="top">Indicates that the TCP protocol is to be
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used.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>IPPROTO_UDP</samp></td>
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<td align="left" valign="top">Indicates that the UDP protocol is to be
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used.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>IPPROTO_RAW</samp></td>
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<td align="left" valign="top">Indicates that communications is to the IP
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layer.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>IPPROTO_ICMP</samp></td>
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<td align="left" valign="top">Indicates that the Internet Control Message
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Protocol (ICMP) is to be used.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>IPPROTO_ICMPV6</samp></td>
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<td align="left" valign="top">Indicates that the Internet Control Message
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Protocol (ICMPv6) is to be used.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><samp>TELPROTO_TEL</samp></td>
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<td align="left" valign="top">Equivalent to specifying the value zero (0).</td>
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</tr>
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</table>
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<br>
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<br>
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</dd>
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</dl>
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<p><strong>Note:</strong> When the <em>type</em> is <samp>SOCK_RAW</samp>, the
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<em>protocol</em> can be set to some predefined protocol number from 0-255. See
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<a href="#HDRSCKUS">Usage Notes</a> for further details.</p>
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<br>
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<h3>Authorities</h3>
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<p>When the SOCKET being created is of type SOCK_RAW, the thread must have
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*ALLOBJ special authority. When the thread does not have this authority, the
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EACCES is returned for <em>errno</em>.</p>
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<br>
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<h3>Return Value</h3>
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<p><em>socket()</em> returns an integer. Possible values are:</p>
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<ul>
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<li>-1 (unsuccessful)</li>
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<li>n (successful), where n is a socket descriptor.</li>
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</ul>
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<br>
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<h3>Error Conditions</h3>
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<p>When <em>socket()</em> fails, <em>errno</em> can be set to one of the
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following:</p>
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<table cellpadding="5">
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<!-- cols="25 75" -->
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<tr>
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<td align="left" valign="top"><em>[EACCES]</em></td>
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<td align="left" valign="top">Permission denied.
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<p>Process does not have the appropriate privileges to create the socket with
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the specified type or protocol.</p>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EAFNOSUPPORT]</em></td>
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<td align="left" valign="top">The type of socket is not supported in this
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protocol family.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EIO]</em></td>
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<td align="left" valign="top">Input/output error.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EMFILE]</em></td>
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<td align="left" valign="top">Too many descriptions for this process.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[ENFILE]</em></td>
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<td align="left" valign="top">Too many descriptions in system.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[ENOBUFS]</em></td>
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<td align="left" valign="top">There is not enough buffer space for the
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requested operation.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EPROTOTYPE]</em></td>
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<td align="left" valign="top">The socket type or protocols are not compatible.
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<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EPROTONOSUPPORT]</em></td>
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<td align="left" valign="top">No protocol of the specified type and domain
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exists.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[ESOCKTNOSUPPORT]</em></td>
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<td align="left" valign="top">The specified socket type is not supported.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EUNATCH]</em></td>
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<td align="left" valign="top">The protocol required to support the specified
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address family is not available at this time.<br>
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<br>
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</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>[EUNKNOWN]</em></td>
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<td align="left" valign="top">Unknown system state.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3>Error Messages</h3>
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<table width="100%" cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<th align="left" valign="top" nowrap>Message ID</th>
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<th align="left" valign="top">Error Message Text</th>
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</tr>
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<tr>
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<td align="left" valign="top">CPE3418 E</td>
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<td align="left" valign="top">Possible APAR condition or hardware failure.</td>
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</tr>
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<tr>
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<td align="left" valign="top">CPF9872 E</td>
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<td align="left" valign="top">Program or service program &1 in library
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&2 ended. Reason code &3.</td>
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</tr>
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<tr>
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<td align="left" valign="top">CPFA081 E</td>
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<td align="left" valign="top">Unable to set return value or error code.</td>
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</tr>
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</table>
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<br>
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<br>
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<h3><a name="HDRSCKUS">Usage Notes</a></h3>
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<ol>
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<li>The socket address families and types supported by sockets are defined in
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<strong><sys/socket.h></strong>. The protocols are defined in
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<strong><netinet/in.h></strong> (Internet protocols).<br>
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<br>
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</li>
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<li>The <samp>AF_UNIX</samp> and <samp>AF_UNIX_CCSID</samp> address family
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supports a protocol of 0 for both <samp>SOCK_STREAM</samp> and
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<samp>SOCK_DGRAM</samp>.<br>
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<br>
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</li>
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<li> The <samp>AF_NS</samp>
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address family is no longer supported as of V5R2.<br>
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<br>
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</li>
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<li>The following tables list the combinations of types and protocols that are
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supported for <samp>AF_INET</samp> and the combinations of types and protocols
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that are supported for <samp>AF_INET6</samp>.<br><br>
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<table border cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<th align="left" valign="top" colspan="2"><em><a name="#TBLSOCKCOM">Supported
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Combinations of Types and Protocols for <samp>AF_INET</samp></a></em></th>
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</tr>
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<tr>
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<th align="left" valign="top">Socket Type</th>
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<th align="left" valign="top">Protocol</th>
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</tr>
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<tr>
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<td align="left" valign="top">STREAM</td>
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<td align="left" valign="top"><samp>IPPROTO_TCP</samp> (see Usage note 5)</td>
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</tr>
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<tr>
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<td align="left" valign="top">DGRAM</td>
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<td align="left" valign="top"><samp>IPPROTO_UDP</samp> </td>
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</tr>
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<tr>
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<td align="left" valign="top">RAW</td>
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<td align="left" valign="top"><samp>IPPROTO_RAW</samp>,
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<samp>IPPROTO_ICMP</samp>, <em>protocol_number</em>, (see Usage note 6)</td>
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</tr>
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</table>
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<br>
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<br>
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<table border cellpadding="5">
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<!-- cols="15 85" -->
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<tr>
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<th align="left" valign="top" colspan="2"><em><a name="TBLSOCKCOM6">Supported
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Combinations of Types and Protocols for <samp>AF_INET6</samp></a></em></th>
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</tr>
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<tr>
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<th align="left" valign="top">Socket Type</th>
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<th align="left" valign="top">Protocol</th>
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</tr>
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<tr>
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<td align="left" valign="top">STREAM</td>
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<td align="left" valign="top"><samp>IPPROTO_TCP</samp> </td>
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</tr>
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<tr>
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<td align="left" valign="top">DGRAM</td>
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<td align="left" valign="top"><samp>IPPROTO_UDP</samp> </td>
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</tr>
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<tr>
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<td align="left" valign="top">RAW</td>
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<td align="left" valign="top"><samp>IPPROTO_RAW</samp>,
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<samp>IPPROTO_ICMPV6</samp>, <em>protocol_number</em>, (see Usage note 6)</td>
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</tr>
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</table>
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<br>
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<br>
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</li>
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<li>The <strong>ALWANYNET</strong> (Allow ANYNET support) network attribute
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allows a customer to select whether a SNA transport can be used for AF_INET
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socket applications.
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<p>The system administrator can see the current status of the
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<strong>ALWANYNET</strong> attribute and can change that status. (This can be
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done by using the Display Network Attributes (DSPNETA) and Change Network
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Attributes (CHGNETA) commands, respectively.)</p>
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<p>If the status is changed, the change takes effect immediately. Also, the
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state of the <strong>ALWANYNET</strong> stays the same across IPLs. For
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example, if the current status is *YES and the system administrator changes the
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value to *NO, the use of <samp>AF_INET</samp> over a transport other than
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TCP/IP is deactivated. If a system IPL is performed after this point, the use
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of <samp>AF_INET</samp> over a SNA transport remains deactivated after the
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system IPL.</p>
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<p>If AF_INET sockets will only be used over a TCP/IP transport, the
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<strong>ALWANYNET</strong> status should be set to *NO to improve CPU
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utilization.</p>
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<p><strong>Note:</strong> If you are also using APPC over TCP/IP
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<strong>ALWANYNET</strong> status needs to be set to *YES.</p>
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</li>
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<li>When the socket type is <samp>SOCK_RAW</samp>, you can specify any protocol
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number between 0-255. Two exceptions are the <samp>IPPROTO_TCP</samp> and
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<samp>IPPROTO_UDP</samp> protocols, which cannot be specified on a socket type
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of <samp>SOCK_RAW</samp> (if you issue <em>socket()</em>, you get an error with
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an error code of <samp>[EPROTONOSUPPORT]</samp>). Each raw socket is associated
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with one IP protocol number, and receives all data for that protocol. For
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example, if two processes create a raw socket with the same protocol number,
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and data is received for the protocol, then both processes get copies of the
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data.
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<p>Protocol numbers 0 (<samp>IPPROTO_IP</samp>) and 255
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(<samp>IPPROTO_RAW</samp>) have some unique characteristics. If a protocol
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number of zero is specified, then IP sends all data received from all the
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protocol numbers (except <samp>IPPROTO_TCP</samp> and <samp>IPPROTO_UDP</samp>
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protocols). If a protocol number of 255 is specified, a user must ensure that
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the IP header data is included in the data sent out on an output operation.</p>
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</li>
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<li>The <samp>AF_TELEPHONY</samp>
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address family is no longer supported as of V5R3.
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</li>
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</ol>
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<br>
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<h3>Related Information</h3>
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<ul>
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<li><a href="socketp.htm">socketpair()</a>--Create a Pair of Sockets</li>
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</ul>
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<br>
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<hr>
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API introduced: V3R1
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<hr>
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<center>
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<table cellpadding="2" cellspacing="2">
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<tr align="center">
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<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> |
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<a href="unix.htm">UNIX-Type APIs</a> |
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<a href="aplist.htm">APIs by category</a> </td>
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</tr>
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</table>
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</center>
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</body>
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</html>
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