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6f9192df61
This removes an overloading of two authentication options where one is very secure (peer) and one is often insecure (ident). Peer is also the name used in libpq from 9.1 to specify the same type of authentication. Also make initdb select peer for local connections when ident is chosen, and ident for TCP connections when peer is chosen. ident keyword in pg_hba.conf is still accepted and maps to peer authentication.
1710 lines
66 KiB
Plaintext
1710 lines
66 KiB
Plaintext
<!-- doc/src/sgml/client-auth.sgml -->
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<chapter id="client-authentication">
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<title>Client Authentication</title>
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<indexterm zone="client-authentication">
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<primary>client authentication</primary>
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</indexterm>
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<para>
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When a client application connects to the database server, it
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specifies which <productname>PostgreSQL</productname> database user name it
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wants to connect as, much the same way one logs into a Unix computer
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as a particular user. Within the SQL environment the active database
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user name determines access privileges to database objects — see
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<xref linkend="user-manag"> for more information. Therefore, it is
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essential to restrict which database users can connect.
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</para>
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<note>
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<para>
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As explained in <xref linkend="user-manag">,
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<productname>PostgreSQL</productname> actually does privilege
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management in terms of <quote>roles</>. In this chapter, we
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consistently use <firstterm>database user</> to mean <quote>role with the
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<literal>LOGIN</> privilege</quote>.
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</para>
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</note>
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<para>
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<firstterm>Authentication</firstterm> is the process by which the
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database server establishes the identity of the client, and by
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extension determines whether the client application (or the user
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who runs the client application) is permitted to connect with the
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database user name that was requested.
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</para>
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<para>
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<productname>PostgreSQL</productname> offers a number of different
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client authentication methods. The method used to authenticate a
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particular client connection can be selected on the basis of
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(client) host address, database, and user.
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</para>
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<para>
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<productname>PostgreSQL</productname> database user names are logically
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separate from user names of the operating system in which the server
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runs. If all the users of a particular server also have accounts on
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the server's machine, it makes sense to assign database user names
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that match their operating system user names. However, a server that
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accepts remote connections might have many database users who have no local operating system
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account, and in such cases there need be no connection between
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database user names and OS user names.
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</para>
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<sect1 id="auth-pg-hba-conf">
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<title>The <filename>pg_hba.conf</filename> File</title>
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<indexterm zone="auth-pg-hba-conf">
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<primary>pg_hba.conf</primary>
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</indexterm>
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<para>
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Client authentication is controlled by a configuration file,
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which traditionally is named
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<filename>pg_hba.conf</filename> and is stored in the database
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cluster's data directory.
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(<acronym>HBA</> stands for host-based authentication.) A default
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<filename>pg_hba.conf</filename> file is installed when the data
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directory is initialized by <command>initdb</command>. It is
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possible to place the authentication configuration file elsewhere,
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however; see the <xref linkend="guc-hba-file"> configuration parameter.
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</para>
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<para>
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The general format of the <filename>pg_hba.conf</filename> file is
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a set of records, one per line. Blank lines are ignored, as is any
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text after the <literal>#</literal> comment character.
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Records cannot be continued across lines.
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A record is made
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up of a number of fields which are separated by spaces and/or tabs.
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Fields can contain white space if the field value is quoted.
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Quoting one of the keywords in a database, user, or address field (e.g.,
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<literal>all</> or <literal>replication</>) makes the word lose its special
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character, and just match a database, user, or host with that name.
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</para>
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<para>
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Each record specifies a connection type, a client IP address range
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(if relevant for the connection type), a database name, a user name,
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and the authentication method to be used for connections matching
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these parameters. The first record with a matching connection type,
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client address, requested database, and user name is used to perform
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authentication. There is no <quote>fall-through</> or
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<quote>backup</>: if one record is chosen and the authentication
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fails, subsequent records are not considered. If no record matches,
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access is denied.
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</para>
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<para>
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A record can have one of the seven formats
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<synopsis>
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local <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-options</replaceable></optional>
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host <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>address</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-options</replaceable></optional>
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hostssl <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>address</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-options</replaceable></optional>
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hostnossl <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>address</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-options</replaceable></optional>
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host <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>IP-address</replaceable> <replaceable>IP-mask</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-options</replaceable></optional>
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hostssl <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>IP-address</replaceable> <replaceable>IP-mask</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-options</replaceable></optional>
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hostnossl <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>IP-address</replaceable> <replaceable>IP-mask</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-options</replaceable></optional>
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</synopsis>
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The meaning of the fields is as follows:
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<variablelist>
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<varlistentry>
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<term><literal>local</literal></term>
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<listitem>
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<para>
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This record matches connection attempts using Unix-domain
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sockets. Without a record of this type, Unix-domain socket
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connections are disallowed.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>host</literal></term>
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<listitem>
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<para>
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This record matches connection attempts made using TCP/IP.
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<literal>host</literal> records match either
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<acronym>SSL</acronym> or non-<acronym>SSL</acronym> connection
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attempts.
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</para>
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<note>
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<para>
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Remote TCP/IP connections will not be possible unless
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the server is started with an appropriate value for the
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<xref linkend="guc-listen-addresses"> configuration parameter,
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since the default behavior is to listen for TCP/IP connections
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only on the local loopback address <literal>localhost</>.
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</para>
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</note>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>hostssl</literal></term>
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<listitem>
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<para>
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This record matches connection attempts made using TCP/IP,
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but only when the connection is made with <acronym>SSL</acronym>
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encryption.
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</para>
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<para>
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To make use of this option the server must be built with
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<acronym>SSL</acronym> support. Furthermore,
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<acronym>SSL</acronym> must be enabled at server start time
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by setting the <xref linkend="guc-ssl"> configuration parameter (see
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<xref linkend="ssl-tcp"> for more information).
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>hostnossl</literal></term>
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<listitem>
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<para>
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This record type has the opposite behavior of <literal>hostssl</>;
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it only matches connection attempts made over
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TCP/IP that do not use <acronym>SSL</acronym>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable>database</replaceable></term>
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<listitem>
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<para>
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Specifies which database name(s) this record matches. The value
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<literal>all</literal> specifies that it matches all databases.
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The value <literal>sameuser</> specifies that the record
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matches if the requested database has the same name as the
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requested user. The value <literal>samerole</> specifies that
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the requested user must be a member of the role with the same
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name as the requested database. (<literal>samegroup</> is an
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obsolete but still accepted spelling of <literal>samerole</>.)
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The value <literal>replication</> specifies that the record
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matches if a replication connection is requested (note that
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replication connections do not specify any particular database).
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Otherwise, this is the name of
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a specific <productname>PostgreSQL</productname> database.
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Multiple database names can be supplied by separating them with
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commas. A separate file containing database names can be specified by
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preceding the file name with <literal>@</>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable>user</replaceable></term>
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<listitem>
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<para>
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Specifies which database user name(s) this record
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matches. The value <literal>all</literal> specifies that it
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matches all users. Otherwise, this is either the name of a specific
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database user, or a group name preceded by <literal>+</>.
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(Recall that there is no real distinction between users and groups
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in <productname>PostgreSQL</>; a <literal>+</> mark really means
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<quote>match any of the roles that are directly or indirectly members
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of this role</>, while a name without a <literal>+</> mark matches
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only that specific role.)
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Multiple user names can be supplied by separating them with commas.
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A separate file containing user names can be specified by preceding the
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file name with <literal>@</>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable>address</replaceable></term>
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<listitem>
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<para>
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Specifies the client machine addresses that this record
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matches. This field can contain either a host name, an IP
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address range, or one of the special key words mentioned below.
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</para>
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<para>
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An IP address is specified in standard dotted decimal
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notation with a <acronym>CIDR</> mask length. The mask
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length indicates the number of high-order bits of the client
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IP address that must match. Bits to the right of this must
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be zero in the given IP address.
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There must not be any white space between the IP address, the
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<literal>/</literal>, and the CIDR mask length.
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</para>
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<para>
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Typical examples of an IP address range specified this way are
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<literal>172.20.143.89/32</literal> for a single host, or
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<literal>172.20.143.0/24</literal> for a small network, or
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<literal>10.6.0.0/16</literal> for a larger one.
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<literal>0.0.0.0/0</literal> represents all
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IPv4 addresses, and <literal>::/0</literal> represents
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all IPv6 addresses.
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To specify a single host, use a CIDR mask of 32 for IPv4 or
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128 for IPv6. In a network address, do not omit trailing zeroes.
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</para>
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<para>
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An IP address given in IPv4 format will match IPv6 connections that
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have the corresponding address, for example <literal>127.0.0.1</>
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will match the IPv6 address <literal>::ffff:127.0.0.1</>. An entry
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given in IPv6 format will match only IPv6 connections, even if the
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represented address is in the IPv4-in-IPv6 range. Note that entries
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in IPv6 format will be rejected if the system's C library does not have
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support for IPv6 addresses.
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</para>
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<para>
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You can also write <literal>all</literal> to match any IP address,
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<literal>samehost</literal> to match any of the server's own IP
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addresses, or <literal>samenet</literal> to match any address in any
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subnet that the server is directly connected to.
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</para>
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<para>
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If a host name is specified (anything that is not an IP address
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or a special key word is processed as a potential host name),
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that name is compared with the result of a reverse name
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resolution of the client's IP address (e.g., reverse DNS
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lookup, if DNS is used). Host name comparisons are case
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insensitive. If there is a match, then a forward name
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resolution (e.g., forward DNS lookup) is performed on the host
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name to check whether any of the addresses it resolves to are
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equal to the client's IP address. If both directions match,
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then the entry is considered to match. (The host name that is
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used in <filename>pg_hba.conf</filename> should be the one that
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address-to-name resolution of the client's IP address returns,
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otherwise the line won't be matched. Some host name databases
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allow associating an IP address with multiple host names, but
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the operating system will only return one host name when asked
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to resolve an IP address.)
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</para>
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<para>
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A host name specification that starts with a dot
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(<literal>.</literal>) matches a suffix of the actual host
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name. So <literal>.example.com</literal> would match
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<literal>foo.example.com</literal> (but not just
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<literal>example.com</literal>).
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</para>
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<para>
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When host names are specified
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in <filename>pg_hba.conf</filename>, you should make sure that
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name resolution is reasonably fast. It can be of advantage to
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set up a local name resolution cache such
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as <command>nscd</command>. Also, you may wish to enable the
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configuration parameter <varname>log_hostname</varname> to see
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the client's host name instead of the IP address in the log.
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</para>
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<sidebar>
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<para>
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Occasionally, users have wondered why host names are handled
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in this seemingly complicated way with two name resolutions
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and requiring reverse lookup of IP addresses, which is
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sometimes not set up or points to some undesirable host name.
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It is primarily for efficiency: A connection attempt requires
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two resolver lookups of the current client's address. If
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there is resolver problem with that address, it becomes only
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that client's problem. A hypothetical alternative
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implementation which only does forward lookups would have to
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resolve every host name mentioned in
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<filename>pg_hba.conf</filename> at every connection attempt.
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That would already be slow by itself. And if there is a
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resolver problem with one of the host names, it becomes
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everyone's problem.
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</para>
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<para>
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Also, a reverse lookup is necessary to implement the suffix
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matching feature, because the actual client host name needs to
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be known in order to match it against the pattern.
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</para>
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<para>
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Note that this behavior is consistent with other popular
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implementations of host name-based access control, such as the
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Apache HTTP Server and TCP Wrappers.
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</para>
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</sidebar>
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<para>
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This field only applies to <literal>host</literal>,
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<literal>hostssl</literal>, and <literal>hostnossl</> records.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable>IP-address</replaceable></term>
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<term><replaceable>IP-mask</replaceable></term>
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<listitem>
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<para>
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These fields can be used as an alternative to the
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<replaceable>CIDR-address</replaceable> notation. Instead of
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specifying the mask length, the actual mask is specified in a
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separate column. For example, <literal>255.0.0.0</> represents an IPv4
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CIDR mask length of 8, and <literal>255.255.255.255</> represents a
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CIDR mask length of 32.
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</para>
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<para>
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These fields only apply to <literal>host</literal>,
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<literal>hostssl</literal>, and <literal>hostnossl</> records.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable>auth-method</replaceable></term>
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<listitem>
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<para>
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Specifies the authentication method to use when a connection matches
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this record. The possible choices are summarized here; details
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are in <xref linkend="auth-methods">.
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<variablelist>
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<varlistentry>
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<term><literal>trust</></term>
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<listitem>
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<para>
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Allow the connection unconditionally. This method
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allows anyone that can connect to the
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<productname>PostgreSQL</productname> database server to login as
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any <productname>PostgreSQL</productname> user they wish,
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without the need for a password or any other authentication. See <xref
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linkend="auth-trust"> for details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>reject</></term>
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<listitem>
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<para>
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Reject the connection unconditionally. This is useful for
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<quote>filtering out</> certain hosts from a group, for example a
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<literal>reject</> line could block a specific host from connecting,
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while a later line allows the remaining hosts in a specific
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network to connect.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>md5</></term>
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<listitem>
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<para>
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Require the client to supply an MD5-encrypted password for
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authentication.
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See <xref linkend="auth-password"> for details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>password</></term>
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<listitem>
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<para>
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Require the client to supply an unencrypted password for
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authentication.
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Since the password is sent in clear text over the
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network, this should not be used on untrusted networks.
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See <xref linkend="auth-password"> for details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>gss</></term>
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<listitem>
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<para>
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Use GSSAPI to authenticate the user. This is only
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available for TCP/IP connections. See <xref
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linkend="gssapi-auth"> for details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>sspi</></term>
|
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<listitem>
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<para>
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Use SSPI to authenticate the user. This is only
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available on Windows. See <xref
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linkend="sspi-auth"> for details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>krb5</></term>
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<listitem>
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<para>
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Use Kerberos V5 to authenticate the user. This is only
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available for TCP/IP connections. See <xref
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linkend="kerberos-auth"> for details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><literal>ident</></term>
|
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<listitem>
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<para>
|
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Obtain the operating system user name of the client
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|
by contacting the ident server on the client
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and check if it matches the requested database user name.
|
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Ident authentication can only be used on TCP/IP
|
|
connections. When specified for local connections, peer
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authentication will be used instead.
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|
See <xref linkend="auth-ident"> for details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
|
|
<term><literal>peer</></term>
|
|
<listitem>
|
|
<para>
|
|
Obtain the operating system user name from the operating system
|
|
and check if it matches the requested database user name.
|
|
This is only available for local connections.
|
|
See <xref linkend="auth-peer"> for details.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>ldap</></term>
|
|
<listitem>
|
|
<para>
|
|
Authenticate using an <acronym>LDAP</> server. See <xref
|
|
linkend="auth-ldap"> for details.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>radius</></term>
|
|
<listitem>
|
|
<para>
|
|
Authenticate using a RADIUS server. See <xref
|
|
linkend="auth-radius"> for details.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>cert</></term>
|
|
<listitem>
|
|
<para>
|
|
Authenticate using SSL client certificates. See
|
|
<xref linkend="auth-cert"> for details.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>pam</></term>
|
|
<listitem>
|
|
<para>
|
|
Authenticate using the Pluggable Authentication Modules
|
|
(PAM) service provided by the operating system. See <xref
|
|
linkend="auth-pam"> for details.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><replaceable>auth-options</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
After the <replaceable>auth-method</> field, there can be field(s) of
|
|
the form <replaceable>name</><literal>=</><replaceable>value</> that
|
|
specify options for the authentication method. Details about which
|
|
options are available for which authentication methods appear below.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
|
|
<para>
|
|
Files included by <literal>@</> constructs are read as lists of names,
|
|
which can be separated by either whitespace or commas. Comments are
|
|
introduced by <literal>#</literal>, just as in
|
|
<filename>pg_hba.conf</filename>, and nested <literal>@</> constructs are
|
|
allowed. Unless the file name following <literal>@</> is an absolute
|
|
path, it is taken to be relative to the directory containing the
|
|
referencing file.
|
|
</para>
|
|
|
|
<para>
|
|
Since the <filename>pg_hba.conf</filename> records are examined
|
|
sequentially for each connection attempt, the order of the records is
|
|
significant. Typically, earlier records will have tight connection
|
|
match parameters and weaker authentication methods, while later
|
|
records will have looser match parameters and stronger authentication
|
|
methods. For example, one might wish to use <literal>trust</>
|
|
authentication for local TCP/IP connections but require a password for
|
|
remote TCP/IP connections. In this case a record specifying
|
|
<literal>trust</> authentication for connections from 127.0.0.1 would
|
|
appear before a record specifying password authentication for a wider
|
|
range of allowed client IP addresses.
|
|
</para>
|
|
|
|
<para>
|
|
The <filename>pg_hba.conf</filename> file is read on start-up and when
|
|
the main server process receives a
|
|
<systemitem>SIGHUP</systemitem><indexterm><primary>SIGHUP</primary></indexterm>
|
|
signal. If you edit the file on an
|
|
active system, you will need to signal the postmaster
|
|
(using <literal>pg_ctl reload</> or <literal>kill -HUP</>) to make it
|
|
re-read the file.
|
|
</para>
|
|
|
|
<tip>
|
|
<para>
|
|
To connect to a particular database, a user must not only pass the
|
|
<filename>pg_hba.conf</filename> checks, but must have the
|
|
<literal>CONNECT</> privilege for the database. If you wish to
|
|
restrict which users can connect to which databases, it's usually
|
|
easier to control this by granting/revoking <literal>CONNECT</> privilege
|
|
than to put the rules in <filename>pg_hba.conf</filename> entries.
|
|
</para>
|
|
</tip>
|
|
|
|
<para>
|
|
Some examples of <filename>pg_hba.conf</filename> entries are shown in
|
|
<xref linkend="example-pg-hba.conf">. See the next section for details on the
|
|
different authentication methods.
|
|
</para>
|
|
|
|
<example id="example-pg-hba.conf">
|
|
<title>Example <filename>pg_hba.conf</filename> Entries</title>
|
|
<programlisting>
|
|
# Allow any user on the local system to connect to any database with
|
|
# any database user name using Unix-domain sockets (the default for local
|
|
# connections).
|
|
#
|
|
# TYPE DATABASE USER ADDRESS METHOD
|
|
local all all trust
|
|
|
|
# The same using local loopback TCP/IP connections.
|
|
#
|
|
# TYPE DATABASE USER ADDRESS METHOD
|
|
host all all 127.0.0.1/32 trust
|
|
|
|
# The same as the previous line, but using a separate netmask column
|
|
#
|
|
# TYPE DATABASE USER IP-ADDRESS IP-MASK METHOD
|
|
host all all 127.0.0.1 255.255.255.255 trust
|
|
|
|
# The same over IPv6.
|
|
#
|
|
# TYPE DATABASE USER ADDRESS METHOD
|
|
host all all ::1/128 trust
|
|
|
|
# The same using a host name (would typically cover both IPv4 and IPv6).
|
|
#
|
|
# TYPE DATABASE USER ADDRESS METHOD
|
|
host all all localhost trust
|
|
|
|
# Allow any user from any host with IP address 192.168.93.x to connect
|
|
# to database "postgres" as the same user name that ident reports for
|
|
# the connection (typically the operating system user name).
|
|
#
|
|
# TYPE DATABASE USER ADDRESS METHOD
|
|
host postgres all 192.168.93.0/24 ident
|
|
|
|
# Allow any user from host 192.168.12.10 to connect to database
|
|
# "postgres" if the user's password is correctly supplied.
|
|
#
|
|
# TYPE DATABASE USER ADDRESS METHOD
|
|
host postgres all 192.168.12.10/32 md5
|
|
|
|
# Allow any user from hosts in the example.com domain to connect to
|
|
# any database if the user's password is correctly supplied.
|
|
#
|
|
# TYPE DATABASE USER ADDRESS METHOD
|
|
host all all .example.com md5
|
|
|
|
# In the absence of preceding "host" lines, these two lines will
|
|
# reject all connections from 192.168.54.1 (since that entry will be
|
|
# matched first), but allow Kerberos 5 connections from anywhere else
|
|
# on the Internet. The zero mask causes no bits of the host IP
|
|
# address to be considered, so it matches any host.
|
|
#
|
|
# TYPE DATABASE USER ADDRESS METHOD
|
|
host all all 192.168.54.1/32 reject
|
|
host all all 0.0.0.0/0 krb5
|
|
|
|
# Allow users from 192.168.x.x hosts to connect to any database, if
|
|
# they pass the ident check. If, for example, ident says the user is
|
|
# "bryanh" and he requests to connect as PostgreSQL user "guest1", the
|
|
# connection is allowed if there is an entry in pg_ident.conf for map
|
|
# "omicron" that says "bryanh" is allowed to connect as "guest1".
|
|
#
|
|
# TYPE DATABASE USER ADDRESS METHOD
|
|
host all all 192.168.0.0/16 ident map=omicron
|
|
|
|
# If these are the only three lines for local connections, they will
|
|
# allow local users to connect only to their own databases (databases
|
|
# with the same name as their database user name) except for administrators
|
|
# and members of role "support", who can connect to all databases. The file
|
|
# $PGDATA/admins contains a list of names of administrators. Passwords
|
|
# are required in all cases.
|
|
#
|
|
# TYPE DATABASE USER ADDRESS METHOD
|
|
local sameuser all md5
|
|
local all @admins md5
|
|
local all +support md5
|
|
|
|
# The last two lines above can be combined into a single line:
|
|
local all @admins,+support md5
|
|
|
|
# The database column can also use lists and file names:
|
|
local db1,db2,@demodbs all md5
|
|
</programlisting>
|
|
</example>
|
|
</sect1>
|
|
|
|
<sect1 id="auth-username-maps">
|
|
<title>User Name Maps</title>
|
|
|
|
<indexterm zone="auth-username-maps">
|
|
<primary>User name maps</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
When using an external authentication system like Ident or GSSAPI,
|
|
the name of the operating system user that initiated the connection
|
|
might not be the same as the database user he needs to connect as.
|
|
In this case, a user name map can be applied to map the operating system
|
|
user name to a database user. To use user name mapping, specify
|
|
<literal>map</literal>=<replaceable>map-name</replaceable>
|
|
in the options field in <filename>pg_hba.conf</filename>. This option is
|
|
supported for all authentication methods that receive external user names.
|
|
Since different mappings might be needed for different connections,
|
|
the name of the map to be used is specified in the
|
|
<replaceable>map-name</replaceable> parameter in <filename>pg_hba.conf</filename>
|
|
to indicate which map to use for each individual connection.
|
|
</para>
|
|
|
|
<para>
|
|
User name maps are defined in the ident map file, which by default is named
|
|
<filename>pg_ident.conf</><indexterm><primary>pg_ident.conf</primary></indexterm>
|
|
and is stored in the
|
|
cluster's data directory. (It is possible to place the map file
|
|
elsewhere, however; see the <xref linkend="guc-ident-file">
|
|
configuration parameter.)
|
|
The ident map file contains lines of the general form:
|
|
<synopsis>
|
|
<replaceable>map-name</> <replaceable>system-username</> <replaceable>database-username</>
|
|
</synopsis>
|
|
Comments and whitespace are handled in the same way as in
|
|
<filename>pg_hba.conf</>. The
|
|
<replaceable>map-name</> is an arbitrary name that will be used to
|
|
refer to this mapping in <filename>pg_hba.conf</filename>. The other
|
|
two fields specify an operating system user name and a matching
|
|
database user name. The same <replaceable>map-name</> can be
|
|
used repeatedly to specify multiple user-mappings within a single map.
|
|
</para>
|
|
<para>
|
|
There is no restriction regarding how many database users a given
|
|
operating system user can correspond to, nor vice versa. Thus, entries
|
|
in a map should be thought of as meaning <quote>this operating system
|
|
user is allowed to connect as this database user</quote>, rather than
|
|
implying that they are equivalent. The connection will be allowed if
|
|
there is any map entry that pairs the user name obtained from the
|
|
external authentication system with the database user name that the
|
|
user has requested to connect as.
|
|
</para>
|
|
<para>
|
|
If the <replaceable>system-username</> field starts with a slash (<literal>/</>),
|
|
the remainder of the field is treated as a regular expression.
|
|
(See <xref linkend="posix-syntax-details"> for details of
|
|
<productname>PostgreSQL</>'s regular expression syntax.) The regular
|
|
expression can include a single capture, or parenthesized subexpression,
|
|
which can then be referenced in the <replaceable>database-username</>
|
|
field as <literal>\1</> (backslash-one). This allows the mapping of
|
|
multiple user names in a single line, which is particularly useful for
|
|
simple syntax substitutions. For example, these entries
|
|
<programlisting>
|
|
mymap /^(.*)@mydomain\.com$ \1
|
|
mymap /^(.*)@otherdomain\.com$ guest
|
|
</programlisting>
|
|
will remove the domain part for users with system user names that end with
|
|
<literal>@mydomain.com</>, and allow any user whose system name ends with
|
|
<literal>@otherdomain.com</> to log in as <literal>guest</>.
|
|
</para>
|
|
|
|
<tip>
|
|
<para>
|
|
Keep in mind that by default, a regular expression can match just part of
|
|
a string. It's usually wise to use <literal>^</> and <literal>$</>, as
|
|
shown in the above example, to force the match to be to the entire
|
|
system user name.
|
|
</para>
|
|
</tip>
|
|
|
|
<para>
|
|
The <filename>pg_ident.conf</filename> file is read on start-up and
|
|
when the main server process receives a
|
|
<systemitem>SIGHUP</systemitem><indexterm><primary>SIGHUP</primary></indexterm>
|
|
signal. If you edit the file on an
|
|
active system, you will need to signal the postmaster
|
|
(using <literal>pg_ctl reload</> or <literal>kill -HUP</>) to make it
|
|
re-read the file.
|
|
</para>
|
|
|
|
<para>
|
|
A <filename>pg_ident.conf</filename> file that could be used in
|
|
conjunction with the <filename>pg_hba.conf</> file in <xref
|
|
linkend="example-pg-hba.conf"> is shown in <xref
|
|
linkend="example-pg-ident.conf">. In this example, anyone
|
|
logged in to a machine on the 192.168 network that does not have the
|
|
operating system user name <literal>bryanh</>, <literal>ann</>, or
|
|
<literal>robert</> would not be granted access. Unix user
|
|
<literal>robert</> would only be allowed access when he tries to
|
|
connect as <productname>PostgreSQL</> user <literal>bob</>, not
|
|
as <literal>robert</> or anyone else. <literal>ann</> would
|
|
only be allowed to connect as <literal>ann</>. User
|
|
<literal>bryanh</> would be allowed to connect as either
|
|
<literal>bryanh</> or as <literal>guest1</>.
|
|
</para>
|
|
|
|
<example id="example-pg-ident.conf">
|
|
<title>An Example <filename>pg_ident.conf</> File</title>
|
|
<programlisting>
|
|
# MAPNAME SYSTEM-USERNAME PG-USERNAME
|
|
|
|
omicron bryanh bryanh
|
|
omicron ann ann
|
|
# bob has user name robert on these machines
|
|
omicron robert bob
|
|
# bryanh can also connect as guest1
|
|
omicron bryanh guest1
|
|
</programlisting>
|
|
</example>
|
|
</sect1>
|
|
|
|
<sect1 id="auth-methods">
|
|
<title>Authentication Methods</title>
|
|
<para>
|
|
The following subsections describe the authentication methods in more detail.
|
|
</para>
|
|
|
|
<sect2 id="auth-trust">
|
|
<title>Trust Authentication</title>
|
|
|
|
<para>
|
|
When <literal>trust</> authentication is specified,
|
|
<productname>PostgreSQL</productname> assumes that anyone who can
|
|
connect to the server is authorized to access the database with
|
|
whatever database user name they specify (even superuser names).
|
|
Of course, restrictions made in the <literal>database</> and
|
|
<literal>user</> columns still apply.
|
|
This method should only be used when there is adequate
|
|
operating-system-level protection on connections to the server.
|
|
</para>
|
|
|
|
<para>
|
|
<literal>trust</> authentication is appropriate and very
|
|
convenient for local connections on a single-user workstation. It
|
|
is usually <emphasis>not</> appropriate by itself on a multiuser
|
|
machine. However, you might be able to use <literal>trust</> even
|
|
on a multiuser machine, if you restrict access to the server's
|
|
Unix-domain socket file using file-system permissions. To do this, set the
|
|
<varname>unix_socket_permissions</varname> (and possibly
|
|
<varname>unix_socket_group</varname>) configuration parameters as
|
|
described in <xref linkend="runtime-config-connection">. Or you
|
|
could set the <varname>unix_socket_directory</varname>
|
|
configuration parameter to place the socket file in a suitably
|
|
restricted directory.
|
|
</para>
|
|
|
|
<para>
|
|
Setting file-system permissions only helps for Unix-socket connections.
|
|
Local TCP/IP connections are not restricted by file-system permissions.
|
|
Therefore, if you want to use file-system permissions for local security,
|
|
remove the <literal>host ... 127.0.0.1 ...</> line from
|
|
<filename>pg_hba.conf</>, or change it to a
|
|
non-<literal>trust</> authentication method.
|
|
</para>
|
|
|
|
<para>
|
|
<literal>trust</> authentication is only suitable for TCP/IP connections
|
|
if you trust every user on every machine that is allowed to connect
|
|
to the server by the <filename>pg_hba.conf</> lines that specify
|
|
<literal>trust</>. It is seldom reasonable to use <literal>trust</>
|
|
for any TCP/IP connections other than those from <systemitem>localhost</> (127.0.0.1).
|
|
</para>
|
|
|
|
</sect2>
|
|
|
|
<sect2 id="auth-password">
|
|
<title>Password Authentication</title>
|
|
|
|
<indexterm>
|
|
<primary>MD5</>
|
|
</indexterm>
|
|
<indexterm>
|
|
<primary>password</primary>
|
|
<secondary>authentication</secondary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The password-based authentication methods are <literal>md5</>
|
|
and <literal>password</>. These methods operate
|
|
similarly except for the way that the password is sent across the
|
|
connection, namely MD5-hashed and clear-text respectively.
|
|
</para>
|
|
|
|
<para>
|
|
If you are at all concerned about password
|
|
<quote>sniffing</> attacks then <literal>md5</> is preferred.
|
|
Plain <literal>password</> should always be avoided if possible.
|
|
However, <literal>md5</> cannot be used with the <xref
|
|
linkend="guc-db-user-namespace"> feature. If the connection is
|
|
protected by SSL encryption then <literal>password</> can be used
|
|
safely (though SSL certificate authentication might be a better
|
|
choice if one is depending on using SSL).
|
|
</para>
|
|
|
|
<para>
|
|
<productname>PostgreSQL</productname> database passwords are
|
|
separate from operating system user passwords. The password for
|
|
each database user is stored in the <literal>pg_authid</> system
|
|
catalog. Passwords can be managed with the SQL commands
|
|
<xref linkend="sql-createuser"> and
|
|
<xref linkend="sql-alteruser">,
|
|
e.g., <userinput>CREATE USER foo WITH PASSWORD 'secret'</userinput>.
|
|
If no password has been set up for a user, the stored password
|
|
is null and password authentication will always fail for that user.
|
|
</para>
|
|
|
|
</sect2>
|
|
|
|
<sect2 id="gssapi-auth">
|
|
<title>GSSAPI Authentication</title>
|
|
|
|
<indexterm zone="gssapi-auth">
|
|
<primary>GSSAPI</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
<productname>GSSAPI</productname> is an industry-standard protocol
|
|
for secure authentication defined in RFC 2743.
|
|
<productname>PostgreSQL</productname> supports
|
|
<productname>GSSAPI</productname> with <productname>Kerberos</productname>
|
|
authentication according to RFC 1964. <productname>GSSAPI</productname>
|
|
provides automatic authentication (single sign-on) for systems
|
|
that support it. The authentication itself is secure, but the
|
|
data sent over the database connection will be sent unencrypted unless
|
|
<acronym>SSL</acronym> is used.
|
|
</para>
|
|
|
|
<para>
|
|
When <productname>GSSAPI</productname> uses
|
|
<productname>Kerberos</productname>, it uses a standard principal
|
|
in the format
|
|
<literal><replaceable>servicename</>/<replaceable>hostname</>@<replaceable>realm</></literal>. For information about the parts of the principal, and
|
|
how to set up the required keys, see <xref linkend="kerberos-auth">.
|
|
</para>
|
|
|
|
<para>
|
|
GSSAPI support has to be enabled when <productname>PostgreSQL</> is built;
|
|
see <xref linkend="installation"> for more information.
|
|
</para>
|
|
|
|
<para>
|
|
The following configuration options are supported for <productname>GSSAPI</productname>:
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><literal>include_realm</literal></term>
|
|
<listitem>
|
|
<para>
|
|
If set to 1, the realm name from the authenticated user
|
|
principal is included in the system user name that's passed through
|
|
user name mapping (<xref linkend="auth-username-maps">). This is
|
|
useful for handling users from multiple realms.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>map</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Allows for mapping between system and database user names. See
|
|
<xref linkend="auth-username-maps"> for details. For a Kerberos
|
|
principal <literal>username/hostbased@EXAMPLE.COM</literal>, the
|
|
user name used for mapping is <literal>username/hostbased</literal>
|
|
if <literal>include_realm</literal> is disabled, and
|
|
<literal>username/hostbased@EXAMPLE.COM</literal> if
|
|
<literal>include_realm</literal> is enabled.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>krb_realm</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the realm to match user principal names against. If this parameter
|
|
is set, only users of that realm will be accepted. If it is not set,
|
|
users of any realm can connect, subject to whatever user name mapping
|
|
is done.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</sect2>
|
|
|
|
<sect2 id="sspi-auth">
|
|
<title>SSPI Authentication</title>
|
|
|
|
<indexterm zone="sspi-auth">
|
|
<primary>SSPI</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
<productname>SSPI</productname> is a <productname>Windows</productname>
|
|
technology for secure authentication with single sign-on.
|
|
<productname>PostgreSQL</productname> will use SSPI in
|
|
<literal>negotiate</literal> mode, which will use
|
|
<productname>Kerberos</productname> when possible and automatically
|
|
fall back to <productname>NTLM</productname> in other cases.
|
|
<productname>SSPI</productname> authentication only works when both
|
|
server and client are running <productname>Windows</productname>.
|
|
</para>
|
|
|
|
<para>
|
|
When using <productname>Kerberos</productname> authentication,
|
|
<productname>SSPI</productname> works the same way
|
|
<productname>GSSAPI</productname> does; see <xref linkend="gssapi-auth">
|
|
for details.
|
|
</para>
|
|
|
|
<para>
|
|
The following configuration options are supported for <productname>SSPI</productname>:
|
|
<variablelist>
|
|
|
|
<varlistentry>
|
|
<term><literal>include_realm</literal></term>
|
|
<listitem>
|
|
<para>
|
|
If set to 1, the realm name from the authenticated user
|
|
principal is included in the system user name that's passed through
|
|
user name mapping (<xref linkend="auth-username-maps">). This is
|
|
useful for handling users from multiple realms.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>map</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Allows for mapping between system and database user names. See
|
|
<xref linkend="auth-username-maps"> for details.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>krb_realm</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the realm to match user principal names against. If this parameter
|
|
is set, only users of that realm will be accepted. If it is not set,
|
|
users of any realm can connect, subject to whatever user name mapping
|
|
is done.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</sect2>
|
|
|
|
<sect2 id="kerberos-auth">
|
|
<title>Kerberos Authentication</title>
|
|
|
|
<indexterm zone="kerberos-auth">
|
|
<primary>Kerberos</primary>
|
|
</indexterm>
|
|
|
|
<note>
|
|
<para>
|
|
Native Kerberos authentication has been deprecated and should be used
|
|
only for backward compatibility. New and upgraded installations are
|
|
encouraged to use the industry-standard <productname>GSSAPI</productname>
|
|
authentication method (see <xref linkend="gssapi-auth">) instead.
|
|
</para>
|
|
</note>
|
|
|
|
<para>
|
|
<productname>Kerberos</productname> is an industry-standard secure
|
|
authentication system suitable for distributed computing over a public
|
|
network. A description of the <productname>Kerberos</productname> system
|
|
is beyond the scope of this document; in full generality it can be
|
|
quite complex (yet powerful). The
|
|
<ulink url="http://www.cmf.nrl.navy.mil/CCS/people/kenh/kerberos-faq.html">
|
|
Kerberos <acronym>FAQ</></ulink> or
|
|
<ulink url="http://web.mit.edu/kerberos/www/">MIT Kerberos page</ulink>
|
|
can be good starting points for exploration.
|
|
Several sources for <productname>Kerberos</> distributions exist.
|
|
<productname>Kerberos</productname> provides secure authentication but
|
|
does not encrypt queries or data passed over the network; for that
|
|
use <acronym>SSL</acronym>.
|
|
</para>
|
|
|
|
<para>
|
|
<productname>PostgreSQL</> supports Kerberos version 5. Kerberos
|
|
support has to be enabled when <productname>PostgreSQL</> is built;
|
|
see <xref linkend="installation"> for more information.
|
|
</para>
|
|
|
|
<para>
|
|
<productname>PostgreSQL</> operates like a normal Kerberos service.
|
|
The name of the service principal is
|
|
<literal><replaceable>servicename</>/<replaceable>hostname</>@<replaceable>realm</></literal>.
|
|
</para>
|
|
|
|
<para>
|
|
<replaceable>servicename</> can be set on the server side using the
|
|
<xref linkend="guc-krb-srvname"> configuration parameter, and on the
|
|
client side using the <literal>krbsrvname</> connection parameter. (See
|
|
also <xref linkend="libpq-connect">.) The installation default can be
|
|
changed from the default <literal>postgres</literal> at build time using
|
|
<literal>./configure --with-krb-srvnam=</><replaceable>whatever</>.
|
|
In most environments,
|
|
this parameter never needs to be changed. However, it is necessary
|
|
when supporting multiple <productname>PostgreSQL</> installations
|
|
on the same host.
|
|
Some Kerberos implementations might also require a different service name,
|
|
such as Microsoft Active Directory which requires the service name
|
|
to be in upper case (<literal>POSTGRES</literal>).
|
|
</para>
|
|
|
|
<para>
|
|
<replaceable>hostname</> is the fully qualified host name of the
|
|
server machine. The service principal's realm is the preferred realm
|
|
of the server machine.
|
|
</para>
|
|
|
|
<para>
|
|
Client principals must have their <productname>PostgreSQL</> database user
|
|
name as their first component, for example
|
|
<literal>pgusername@realm</>. Alternatively, you can use a user name
|
|
mapping to map from the first component of the principal name to the
|
|
database user name. By default, the realm of the client is
|
|
not checked by <productname>PostgreSQL</>. If you have cross-realm
|
|
authentication enabled and need to verify the realm, use the
|
|
<literal>krb_realm</> parameter, or enable <literal>include_realm</>
|
|
and use user name mapping to check the realm.
|
|
</para>
|
|
|
|
<para>
|
|
Make sure that your server keytab file is readable (and preferably
|
|
only readable) by the <productname>PostgreSQL</productname> server
|
|
account. (See also <xref linkend="postgres-user">.) The location
|
|
of the key file is specified by the <xref
|
|
linkend="guc-krb-server-keyfile"> configuration
|
|
parameter. The default is
|
|
<filename>/usr/local/pgsql/etc/krb5.keytab</> (or whatever
|
|
directory was specified as <varname>sysconfdir</> at build time).
|
|
</para>
|
|
|
|
<para>
|
|
The keytab file is generated by the Kerberos software; see the
|
|
Kerberos documentation for details. The following example is
|
|
for MIT-compatible Kerberos 5 implementations:
|
|
<screen>
|
|
<prompt>kadmin% </><userinput>ank -randkey postgres/server.my.domain.org</>
|
|
<prompt>kadmin% </><userinput>ktadd -k krb5.keytab postgres/server.my.domain.org</>
|
|
</screen>
|
|
</para>
|
|
|
|
<para>
|
|
When connecting to the database make sure you have a ticket for a
|
|
principal matching the requested database user name. For example, for
|
|
database user name <literal>fred</>, principal
|
|
<literal>fred@EXAMPLE.COM</> would be able to connect. To also allow
|
|
principal <literal>fred/users.example.com@EXAMPLE.COM</>, use a user name
|
|
map, as described in <xref linkend="auth-username-maps">.
|
|
</para>
|
|
|
|
<para>
|
|
If you use <ulink url="http://modauthkerb.sf.net">
|
|
<application>mod_auth_kerb</application></ulink>
|
|
and <application>mod_perl</application> on your
|
|
<productname>Apache</productname> web server, you can use
|
|
<literal>AuthType KerberosV5SaveCredentials</literal> with a
|
|
<application>mod_perl</application> script. This gives secure
|
|
database access over the web, with no additional passwords required.
|
|
</para>
|
|
|
|
<para>
|
|
The following configuration options are supported for
|
|
<productname>Kerberos</productname>:
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><literal>map</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Allows for mapping between system and database user names. See
|
|
<xref linkend="auth-username-maps"> for details.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>include_realm</literal></term>
|
|
<listitem>
|
|
<para>
|
|
If set to 1, the realm name from the authenticated user
|
|
principal is included in the system user name that's passed through
|
|
user name mapping (<xref linkend="auth-username-maps">). This is
|
|
useful for handling users from multiple realms.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>krb_realm</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the realm to match user principal names against. If this parameter
|
|
is set, only users of that realm will be accepted. If it is not set,
|
|
users of any realm can connect, subject to whatever user name mapping
|
|
is done.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>krb_server_hostname</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Sets the host name part of the service principal.
|
|
This, combined with <varname>krb_srvname</>, is used to generate
|
|
the complete service principal, that is
|
|
<varname>krb_srvname</><literal>/</><varname>krb_server_hostname</><literal>@</>REALM.
|
|
If not set, the default is the server host name.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</sect2>
|
|
|
|
<sect2 id="auth-ident">
|
|
<title>Ident Authentication</title>
|
|
|
|
<indexterm>
|
|
<primary>ident</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
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.
|
|
</para>
|
|
|
|
<note>
|
|
<para>
|
|
When ident is specified for a local (non-TCP/IP) connection,
|
|
peer authentication (see <xref linkend="auth-peer">) will be
|
|
used instead.
|
|
</para>
|
|
</note>
|
|
|
|
<para>
|
|
The following configuration options are supported for <productname>ident</productname>:
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><literal>map</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Allows for mapping between system and database user names. See
|
|
<xref linkend="auth-username-maps"> for details.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
|
|
<para>
|
|
The <quote>Identification Protocol</quote> 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 <quote>What user initiated the
|
|
connection that goes out of your port <replaceable>X</replaceable>
|
|
and connects to my port <replaceable>Y</replaceable>?</quote>.
|
|
Since <productname>PostgreSQL</> knows both <replaceable>X</> and
|
|
<replaceable>Y</> 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.
|
|
</para>
|
|
|
|
<para>
|
|
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 he chooses. 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:
|
|
<blockquote>
|
|
<attribution>RFC 1413</attribution>
|
|
<para>
|
|
The Identification Protocol is not intended as an authorization
|
|
or access control protocol.
|
|
</para>
|
|
</blockquote>
|
|
</para>
|
|
|
|
<para>
|
|
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 <emphasis>must not</> be
|
|
used when using the ident server with <productname>PostgreSQL</>,
|
|
since <productname>PostgreSQL</> does not have any way to decrypt the
|
|
returned string to determine the actual user name.
|
|
</para>
|
|
</sect2>
|
|
|
|
<sect2 id="auth-peer">
|
|
<title>Peer Authentication</title>
|
|
|
|
<indexterm>
|
|
<primary>peer</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
The peer authentication method works by obtaining the client's
|
|
operating system user name from the kernel and using it as the
|
|
allowed database user name (with optional user name mapping). This
|
|
is only supported on local connections.
|
|
</para>
|
|
|
|
<para>
|
|
The following configuration options are supported for <productname>peer</productname>:
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><literal>map</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Allows for mapping between system and database user names. See
|
|
<xref linkend="auth-username-maps"> for details.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
|
|
<para>
|
|
Peer authentication is only available on systems supporting
|
|
<symbol>SO_PEERCRED</symbol> requests for
|
|
Unix-domain sockets (currently <systemitem
|
|
class="osname">Linux</>, <systemitem class="osname">FreeBSD</>,
|
|
<systemitem class="osname">NetBSD</>, <systemitem class="osname">OpenBSD</>,
|
|
<systemitem class="osname">BSD/OS</>, and <systemitem class="osname">Solaris</systemitem>).
|
|
<productname>PostgreSQL</> uses <symbol>SO_PEERCRED</symbol> to find out
|
|
the operating system name of the connected client process.
|
|
</para>
|
|
|
|
</sect2>
|
|
|
|
<sect2 id="auth-ldap">
|
|
<title>LDAP Authentication</title>
|
|
|
|
<indexterm zone="auth-ldap">
|
|
<primary>LDAP</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
This authentication method operates similarly to
|
|
<literal>password</literal> except that it uses LDAP
|
|
as the password verification method. LDAP is used only to validate
|
|
the user name/password pairs. Therefore the user must already
|
|
exist in the database before LDAP can be used for
|
|
authentication.
|
|
</para>
|
|
|
|
<para>
|
|
LDAP authentication can operate in two modes. In the first mode,
|
|
the server will bind to the distinguished name constructed as
|
|
<replaceable>prefix</> <replaceable>username</> <replaceable>suffix</>.
|
|
Typically, the <replaceable>prefix</> parameter is used to specify
|
|
<literal>cn=</>, or <replaceable>DOMAIN</><literal>\</> in an Active
|
|
Directory environment. <replaceable>suffix</> is used to specify the
|
|
remaining part of the DN in a non-Active Directory environment.
|
|
</para>
|
|
|
|
<para>
|
|
In the second mode, the server first binds to the LDAP directory with
|
|
a fixed user name and password, specified with <replaceable>ldapbinduser</>
|
|
and <replaceable>ldapbinddn</>, and performs a search for the user trying
|
|
to log in to the database. If no user and password is configured, an
|
|
anonymous bind will be attempted to the directory. The search will be
|
|
performed over the subtree at <replaceable>ldapbasedn</>, and will try to
|
|
do an exact match of the attribute specified in
|
|
<replaceable>ldapsearchattribute</>. If no attribute is specified, the
|
|
<literal>uid</> attribute will be used. Once the user has been found in
|
|
this search, the server disconnects and re-binds to the directory as
|
|
this user, using the password specified by the client, to verify that the
|
|
login is correct. This method allows for significantly more flexibility
|
|
in where the user objects are located in the directory, but will cause
|
|
two separate connections to the LDAP server to be made.
|
|
</para>
|
|
|
|
<para>
|
|
The following configuration options are supported for LDAP:
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><literal>ldapserver</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Name or IP of LDAP server to connect to.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><literal>ldapport</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Port number on LDAP server to connect to. If no port is specified,
|
|
the LDAP library's default port setting will be used.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><literal>ldaptls</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Set to 1 to make the connection between PostgreSQL and the
|
|
LDAP server use TLS encryption. Note that this only encrypts
|
|
the traffic to the LDAP server — the connection to the client
|
|
will still be unencrypted unless SSL is used.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><literal>ldapprefix</literal></term>
|
|
<listitem>
|
|
<para>
|
|
String to prepend to the user name when forming the DN to bind as,
|
|
when doing simple bind authentication.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><literal>ldapsuffix</literal></term>
|
|
<listitem>
|
|
<para>
|
|
String to append to the user name when forming the DN to bind as,
|
|
when doing simple bind authentication.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><literal>ldapbasedn</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Root DN to begin the search for the user in, when doing search+bind
|
|
authentication.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><literal>ldapbinddn</literal></term>
|
|
<listitem>
|
|
<para>
|
|
DN of user to bind to the directory with to perform the search when
|
|
doing search+bind authentication.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><literal>ldapbindpasswd</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Password for user to bind to the directory with to perform the search
|
|
when doing search+bind authentication.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><literal>ldapsearchattribute</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Attribute to match against the user name in the search when doing
|
|
search+bind authentication.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
|
|
<note>
|
|
<para>
|
|
Since LDAP often uses commas and spaces to separate the different
|
|
parts of a DN, it is often necessary to use double-quoted parameter
|
|
values when configuring LDAP options, for example:
|
|
<programlisting>
|
|
ldapserver=ldap.example.net ldapprefix="cn=" ldapsuffix=", dc=example, dc=net"
|
|
</programlisting>
|
|
</para>
|
|
</note>
|
|
|
|
</sect2>
|
|
|
|
<sect2 id="auth-radius">
|
|
<title>RADIUS Authentication</title>
|
|
|
|
<indexterm zone="auth-radius">
|
|
<primary>RADIUS</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
This authentication method operates similarly to
|
|
<literal>password</literal> except that it uses RADIUS
|
|
as the password verification method. RADIUS is used only to validate
|
|
the user name/password pairs. Therefore the user must already
|
|
exist in the database before RADIUS can be used for
|
|
authentication.
|
|
</para>
|
|
|
|
<para>
|
|
When using RADIUS authentication, an Access Request message will be sent
|
|
to the configured RADIUS server. This request will be of type
|
|
<literal>Authenticate Only</literal>, and include parameters for
|
|
<literal>user name</>, <literal>password</> (encrypted) and
|
|
<literal>NAS Identifier</>. The request will be encrypted using
|
|
a secret shared with the server. The RADIUS server will respond to
|
|
this server with either <literal>Access Accept</> or
|
|
<literal>Access Reject</>. There is no support for RADIUS accounting.
|
|
</para>
|
|
|
|
<para>
|
|
The following configuration options are supported for RADIUS:
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><literal>radiusserver</literal></term>
|
|
<listitem>
|
|
<para>
|
|
The name or IP address of the RADIUS server to connect to.
|
|
This parameter is required.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>radiussecret</literal></term>
|
|
<listitem>
|
|
<para>
|
|
The shared secret used when talking securely to the RADIUS
|
|
server. This must have exactly the same value on the PostgreSQL
|
|
and RADIUS servers. It is recommended that this be a string of
|
|
at least 16 characters. This parameter is required.
|
|
<note>
|
|
<para>
|
|
The encryption vector used will only be cryptographically
|
|
strong if <productname>PostgreSQL</> is built with support for
|
|
<productname>OpenSSL</>. In other cases, the transmission to the
|
|
RADIUS server should only be considered obfuscated, not secured, and
|
|
external security measures should be applied if necessary.
|
|
</para>
|
|
</note>
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>radiusport</literal></term>
|
|
<listitem>
|
|
<para>
|
|
The port number on the RADIUS server to connect to. If no port
|
|
is specified, the default port <literal>1812</> will be used.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>radiusidentifier</literal></term>
|
|
<listitem>
|
|
<para>
|
|
The string used as <literal>NAS Identifier</> in the RADIUS
|
|
requests. This parameter can be used as a second parameter
|
|
identifying for example which database user the user is attempting
|
|
to authenticate as, which can be used for policy matching on
|
|
the RADIUS server. If no identifier is specified, the default
|
|
<literal>postgresql</> will be used.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
</para>
|
|
</sect2>
|
|
|
|
<sect2 id="auth-cert">
|
|
<title>Certificate Authentication</title>
|
|
|
|
<indexterm zone="auth-cert">
|
|
<primary>Certificate</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
This authentication method uses SSL client certificates to perform
|
|
authentication. It is therefore only available for SSL connections.
|
|
When using this authentication method, the server will require that
|
|
the client provide a valid certificate. No password prompt will be sent
|
|
to the client. The <literal>cn</literal> (Common Name) attribute of the
|
|
certificate
|
|
will be compared to the requested database user name, and if they match
|
|
the login will be allowed. User name mapping can be used to allow
|
|
<literal>cn</literal> to be different from the database user name.
|
|
</para>
|
|
|
|
<para>
|
|
The following configuration options are supported for SSL certificate
|
|
authentication:
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><literal>map</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Allows for mapping between system and database user names. See
|
|
<xref linkend="auth-username-maps"> for details.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</sect2>
|
|
|
|
<sect2 id="auth-pam">
|
|
<title>PAM Authentication</title>
|
|
|
|
<indexterm zone="auth-pam">
|
|
<primary>PAM</primary>
|
|
</indexterm>
|
|
|
|
<para>
|
|
This authentication method operates similarly to
|
|
<literal>password</literal> except that it uses PAM (Pluggable
|
|
Authentication Modules) as the authentication mechanism. The
|
|
default PAM service name is <literal>postgresql</literal>.
|
|
PAM is used only to validate user name/password pairs.
|
|
Therefore the user must already exist in the database before PAM
|
|
can be used for authentication. For more information about
|
|
PAM, please read the <ulink url="http://www.kernel.org/pub/linux/libs/pam/">
|
|
<productname>Linux-PAM</> Page</ulink>
|
|
and the <ulink url="http://www.sun.com/software/solaris/pam/">
|
|
<systemitem class="osname">Solaris</> PAM Page</ulink>.
|
|
</para>
|
|
|
|
<para>
|
|
The following configuration options are supported for PAM:
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><literal>pamservice</literal></term>
|
|
<listitem>
|
|
<para>
|
|
PAM service name.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
|
|
<note>
|
|
<para>
|
|
If PAM is set up to read <filename>/etc/shadow</>, authentication
|
|
will fail because the PostgreSQL server is started by a non-root
|
|
user. However, this is not an issue when PAM is configured to use
|
|
LDAP or other authentication methods.
|
|
</para>
|
|
</note>
|
|
</sect2>
|
|
</sect1>
|
|
|
|
<sect1 id="client-authentication-problems">
|
|
<title>Authentication Problems</title>
|
|
|
|
<para>
|
|
Authentication failures and related problems generally
|
|
manifest themselves through error messages like the following:
|
|
</para>
|
|
|
|
<para>
|
|
<programlisting>
|
|
FATAL: no pg_hba.conf entry for host "123.123.123.123", user "andym", database "testdb"
|
|
</programlisting>
|
|
This is what you are most likely to get if you succeed in contacting
|
|
the server, but it does not want to talk to you. As the message
|
|
suggests, the server refused the connection request because it found
|
|
no matching entry in its <filename>pg_hba.conf</filename>
|
|
configuration file.
|
|
</para>
|
|
|
|
<para>
|
|
<programlisting>
|
|
FATAL: password authentication failed for user "andym"
|
|
</programlisting>
|
|
Messages like this indicate that you contacted the server, and it is
|
|
willing to talk to you, but not until you pass the authorization
|
|
method specified in the <filename>pg_hba.conf</filename> file. Check
|
|
the password you are providing, or check your Kerberos or ident
|
|
software if the complaint mentions one of those authentication
|
|
types.
|
|
</para>
|
|
|
|
<para>
|
|
<programlisting>
|
|
FATAL: user "andym" does not exist
|
|
</programlisting>
|
|
The indicated database user name was not found.
|
|
</para>
|
|
|
|
<para>
|
|
<programlisting>
|
|
FATAL: database "testdb" does not exist
|
|
</programlisting>
|
|
The database you are trying to connect to does not exist. Note that
|
|
if you do not specify a database name, it defaults to the database
|
|
user name, which might or might not be the right thing.
|
|
</para>
|
|
|
|
<tip>
|
|
<para>
|
|
The server log might contain more information about an
|
|
authentication failure than is reported to the client. If you are
|
|
confused about the reason for a failure, check the server log.
|
|
</para>
|
|
</tip>
|
|
</sect1>
|
|
|
|
</chapter>
|