2010-09-20 22:08:53 +02:00
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<!-- doc/src/sgml/passwordcheck.sgml -->
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2009-11-18 22:57:56 +01:00
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2011-05-08 04:29:20 +02:00
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<sect1 id="passwordcheck" xreflabel="passwordcheck">
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2009-11-18 22:57:56 +01:00
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<title>passwordcheck</title>
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<indexterm zone="passwordcheck">
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<primary>passwordcheck</primary>
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</indexterm>
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<para>
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The <filename>passwordcheck</filename> module checks users' passwords
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whenever they are set with
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2010-04-03 09:23:02 +02:00
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<xref linkend="SQL-CREATEROLE"> or
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<xref linkend="SQL-ALTERROLE">.
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2009-11-18 22:57:56 +01:00
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If a password is considered too weak, it will be rejected and
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the command will terminate with an error.
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</para>
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<para>
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To enable this module, add <literal>'$libdir/passwordcheck'</literal>
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to <xref linkend="guc-shared-preload-libraries"> in
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<filename>postgresql.conf</filename>, then restart the server.
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</para>
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<para>
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You can adapt this module to your needs by changing the source code.
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For example, you can use
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<ulink url="http://sourceforge.net/projects/cracklib/">CrackLib</ulink>
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to check passwords — this only requires uncommenting
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two lines in the <filename>Makefile</filename> and rebuilding the
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module. (We cannot include <productname>CrackLib</productname>
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by default for license reasons.)
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Without <productname>CrackLib</productname>, the module enforces a few
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simple rules for password strength, which you can modify or extend
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as you see fit.
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</para>
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<caution>
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<para>
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To prevent unencrypted passwords from being sent across the network,
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written to the server log or otherwise stolen by a database administrator,
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<productname>PostgreSQL</productname> allows the user to supply
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pre-encrypted passwords. Many client programs make use of this
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functionality and encrypt the password before sending it to the server.
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</para>
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<para>
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This limits the usefulness of the <filename>passwordcheck</filename>
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module, because in that case it can only try to guess the password.
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For this reason, <filename>passwordcheck</filename> is not
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2012-08-14 18:36:35 +02:00
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recommended if your security requirements are high.
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2014-01-15 17:24:01 +01:00
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It is more secure to use an external authentication method such as GSSAPI
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2009-11-18 22:57:56 +01:00
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(see <xref linkend="client-authentication">) than to rely on
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passwords within the database.
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</para>
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<para>
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Alternatively, you could modify <filename>passwordcheck</filename>
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to reject pre-encrypted passwords, but forcing users to set their
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passwords in clear text carries its own security risks.
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</para>
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</caution>
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</sect1>
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