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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>20.8. 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 V1.79.1" /><link rel="prev" href="sspi-auth.html" title="20.7. SSPI Authentication" /><link rel="next" href="auth-peer.html" title="20.9. Peer Authentication" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">20.8. Ident Authentication</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sspi-auth.html" title="20.7. SSPI Authentication">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="client-authentication.html" title="Chapter 20. Client Authentication">Up</a></td><th width="60%" align="center">Chapter 20. Client Authentication</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 12.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="auth-peer.html" title="20.9. Peer Authentication">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="AUTH-IDENT"><div class="titlepage"><div><div><h2 class="title" style="clear: both">20.8. Ident Authentication</h2></div></div></div><a id="id-1.6.7.15.2" 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="20.9. Peer Authentication">Section 20.9</a>) will be
- used instead.
- </p></div><p>
- The following configuration options are supported for <span class="productname">ident</span>:
- </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="20.2. User Name Maps">Section 20.2</a> for details.
- </p></dd></dl></div><p>
- </p><p>
- The <span class="quote">“<span class="quote">Identification Protocol</span>”</span> is described in
- RFC 1413. 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">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="client-authentication.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="auth-peer.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">20.7. SSPI Authentication </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 20.9. Peer Authentication</td></tr></table></div></body></html>
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