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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>21.8. Ident 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="sspi-auth.html" title="21.7. SSPI Authentication" /><link rel="next" href="auth-peer.html" title="21.9. Peer Authentication" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">21.8. Ident Authentication</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sspi-auth.html" title="21.7. SSPI Authentication">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="client-authentication.html" title="Chapter 21. Client Authentication">Up</a></td><th width="60%" align="center">Chapter 21. Client Authentication</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-peer.html" title="21.9. Peer Authentication">Next</a></td></tr></table><hr /></div><div class="sect1" id="AUTH-IDENT"><div class="titlepage"><div><div><h2 class="title" style="clear: both">21.8. Ident Authentication <a href="#AUTH-IDENT" class="id_link">#</a></h2></div></div></div><a id="id-1.6.8.15.2" class="indexterm"></a><p> |
| The ident authentication method works by obtaining the client's |
| operating system user name from an ident server and using it as |
| the allowed database user name (with an optional user name mapping). |
| This is only supported on TCP/IP connections. |
| </p><div class="note"><h3 class="title">Note</h3><p> |
| When ident is specified for a local (non-TCP/IP) connection, |
| peer authentication (see <a class="xref" href="auth-peer.html" title="21.9. Peer Authentication">Section 21.9</a>) will be |
| used instead. |
| </p></div><p> |
| The following configuration options are supported for <code class="literal">ident</code>: |
| </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">map</code></span></dt><dd><p> |
| Allows for mapping between system and database user names. See |
| <a class="xref" href="auth-username-maps.html" title="21.2. User Name Maps">Section 21.2</a> for details. |
| </p></dd></dl></div><p> |
| </p><p> |
| The <span class="quote">“<span class="quote">Identification Protocol</span>”</span> is described in |
| <a class="ulink" href="https://datatracker.ietf.org/doc/html/rfc1413" target="_top">RFC 1413</a>. |
| Virtually every Unix-like |
| operating system ships with an ident server that listens on TCP |
| port 113 by default. The basic functionality of an ident server |
| is to answer questions like <span class="quote">“<span class="quote">What user initiated the |
| connection that goes out of your port <em class="replaceable"><code>X</code></em> |
| and connects to my port <em class="replaceable"><code>Y</code></em>?</span>”</span>. |
| Since <span class="productname">PostgreSQL</span> knows both <em class="replaceable"><code>X</code></em> and |
| <em class="replaceable"><code>Y</code></em> when a physical connection is established, it |
| can interrogate the ident server on the host of the connecting |
| client and can theoretically determine the operating system user |
| for any given connection. |
| </p><p> |
| The drawback of this procedure is that it depends on the integrity |
| of the client: if the client machine is untrusted or compromised, |
| an attacker could run just about any program on port 113 and |
| return any user name they choose. This authentication method is |
| therefore only appropriate for closed networks where each client |
| machine is under tight control and where the database and system |
| administrators operate in close contact. In other words, you must |
| trust the machine running the ident server. |
| Heed the warning: |
| </p><div class="blockquote"><table border="0" class="blockquote" style="width: 100%; cellspacing: 0; cellpadding: 0;" summary="Block quote"><tr><td width="10%" valign="top"> </td><td width="80%" valign="top"><p> |
| The Identification Protocol is not intended as an authorization |
| or access control protocol. |
| </p></td><td width="10%" valign="top"> </td></tr><tr><td width="10%" valign="top"> </td><td colspan="2" align="right" valign="top">--<span class="attribution">RFC 1413</span></td></tr></table></div><p> |
| </p><p> |
| Some ident servers have a nonstandard option that causes the returned |
| user name to be encrypted, using a key that only the originating |
| machine's administrator knows. This option <span class="emphasis"><em>must not</em></span> be |
| used when using the ident server with <span class="productname">PostgreSQL</span>, |
| since <span class="productname">PostgreSQL</span> does not have any way to decrypt the |
| returned string to determine the actual user name. |
| </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sspi-auth.html" title="21.7. SSPI Authentication">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="client-authentication.html" title="Chapter 21. Client Authentication">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="auth-peer.html" title="21.9. Peer Authentication">Next</a></td></tr><tr><td width="40%" align="left" valign="top">21.7. SSPI Authentication </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"> 21.9. Peer Authentication</td></tr></table></div></body></html> |
