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Edit File: PortOverride.html
<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Port/instance override syntax</title><link rel="stylesheet" type="text/css" href="userguide.css" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="home" href="index.html" title="FreeTDS User Guide" /><link rel="up" href="install.html" title="Chapter 3. Install FreeTDS" /><link rel="prev" href="envvar.html" title="Environment variables" /><link rel="next" href="ConfirmInstall.html" title="Confirm the installation" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Port/instance override syntax</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="envvar.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Install <span class="productname">FreeTDS</span></th><td width="20%" align="right"> <a accesskey="n" href="ConfirmInstall.html">Next</a></td></tr></table><hr /></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="PortOverride"></a>Port/instance override syntax</h2></div></div></div><p>The port to which to connect can be overridden using a <span class="productname">FreeTDS</span> extended syntax.</p><p>A port may be appended to the servername in the form <code class="literal"><em class="replaceable"><code>servername</code></em>:<em class="replaceable"><code>port</code></em></code>. <span class="productname">FreeTDS</span> will attempt to connect to specified port. Please note <em class="replaceable"><code>port</code></em> must be a number; a service name is not supported.</p><p>If you specify <code class="literal"><em class="replaceable"><code>servername</code></em>\<em class="replaceable"><code>instance</code></em></code> as servername during login, <span class="productname">FreeTDS</span> will attempt to connect to specified instance. Only Microsoft SQL Server instances are supported. (This server feature was introduced with Microsoft SQL Server 2000.)</p><p>Note that other <code class="filename">freetds.conf</code> properties still apply.</p><p>For the technically curious: each Microsoft SQL Server <em class="firstterm">instance</em> appears on the network as a server listening at a port. The old way — and it still works — is to designate each instance in <code class="filename">freetds.conf</code> as a separate server. The new <span class="quote">“<span class="quote">named instance</span>”</span> notation, if we can call it that, instead uses the server to discover the port. The library sends a UDP packet containing the instance name to the server at a <span class="emphasis"><em>well known port</em></span>, port 1434. The server responds with a port number. <span class="productname">FreeTDS</span> then uses that number to connect in the usual way.</p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="envvar.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="install.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ConfirmInstall.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Environment variables </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Confirm the installation</td></tr></table></div></body></html>