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<!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>Chapter 21. Client Authentication</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="runtime-config-short.html" title="20.18. Short Options" /><link rel="next" href="auth-pg-hba-conf.html" title="21.1. The pg_hba.conf File" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">Chapter 21. Client Authentication</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="runtime-config-short.html" title="20.18. Short Options">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="admin.html" title="Part III. Server Administration">Up</a></td><th width="60%" align="center">Part III. Server Administration</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="auth-pg-hba-conf.html" title="21.1. The pg_hba.conf File">Next</a></td></tr></table><hr /></div><div class="chapter" id="CLIENT-AUTHENTICATION"><div class="titlepage"><div><div><h2 class="title">Chapter 21. Client Authentication</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="sect1"><a href="auth-pg-hba-conf.html">21.1. The <code class="filename">pg_hba.conf</code> File</a></span></dt><dt><span class="sect1"><a href="auth-username-maps.html">21.2. User Name Maps</a></span></dt><dt><span class="sect1"><a href="auth-methods.html">21.3. Authentication Methods</a></span></dt><dt><span class="sect1"><a href="auth-trust.html">21.4. Trust Authentication</a></span></dt><dt><span class="sect1"><a href="auth-password.html">21.5. Password Authentication</a></span></dt><dt><span class="sect1"><a href="gssapi-auth.html">21.6. GSSAPI Authentication</a></span></dt><dt><span class="sect1"><a href="sspi-auth.html">21.7. SSPI Authentication</a></span></dt><dt><span class="sect1"><a href="auth-ident.html">21.8. Ident Authentication</a></span></dt><dt><span class="sect1"><a href="auth-peer.html">21.9. Peer Authentication</a></span></dt><dt><span class="sect1"><a href="auth-ldap.html">21.10. LDAP Authentication</a></span></dt><dt><span class="sect1"><a href="auth-radius.html">21.11. RADIUS Authentication</a></span></dt><dt><span class="sect1"><a href="auth-cert.html">21.12. Certificate Authentication</a></span></dt><dt><span class="sect1"><a href="auth-pam.html">21.13. PAM Authentication</a></span></dt><dt><span class="sect1"><a href="auth-bsd.html">21.14. BSD Authentication</a></span></dt><dt><span class="sect1"><a href="client-authentication-problems.html">21.15. Authentication Problems</a></span></dt></dl></div><a id="id-1.6.8.2" class="indexterm"></a><p>
When a client application connects to the database server, it
specifies which <span class="productname">PostgreSQL</span> database user name it
wants to connect as, much the same way one logs into a Unix computer
as a particular user. Within the SQL environment the active database
user name determines access privileges to database objects — see
<a class="xref" href="user-manag.html" title="Chapter 22. Database Roles">Chapter 22</a> for more information. Therefore, it is
essential to restrict which database users can connect.
</p><div class="note"><h3 class="title">Note</h3><p>
As explained in <a class="xref" href="user-manag.html" title="Chapter 22. Database Roles">Chapter 22</a>,
<span class="productname">PostgreSQL</span> actually does privilege
management in terms of <span class="quote">“<span class="quote">roles</span>”</span>. In this chapter, we
consistently use <em class="firstterm">database user</em> to mean <span class="quote">“<span class="quote">role with the
<code class="literal">LOGIN</code> privilege</span>”</span>.
</p></div><p>
<em class="firstterm">Authentication</em> is the process by which the
database server establishes the identity of the client, and by
extension determines whether the client application (or the user
who runs the client application) is permitted to connect with the
database user name that was requested.
</p><p>
<span class="productname">PostgreSQL</span> offers a number of different
client authentication methods. The method used to authenticate a
particular client connection can be selected on the basis of
(client) host address, database, and user.
</p><p>
<span class="productname">PostgreSQL</span> database user names are logically
separate from user names of the operating system in which the server
runs. If all the users of a particular server also have accounts on
the server's machine, it makes sense to assign database user names
that match their operating system user names. However, a server that
accepts remote connections might have many database users who have no local
operating system
account, and in such cases there need be no connection between
database user names and OS user names.
</p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="runtime-config-short.html" title="20.18. Short Options">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="admin.html" title="Part III. Server Administration">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="auth-pg-hba-conf.html" title="21.1. The pg_hba.conf File">Next</a></td></tr><tr><td width="40%" align="left" valign="top">20.18. Short Options </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 21.1. The <code class="filename">pg_hba.conf</code> File</td></tr></table></div></body></html>