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><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AUTH-METHODS"
>19.3. Authentication methods</A
></H1
><P
> The following subsections describe the authentication methods in more detail.
</P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AUTH-TRUST"
>19.3.1. Trust authentication</A
></H2
><P
> When <TT
CLASS="LITERAL"
>trust</TT
> authentication is specified,
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> 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 <TT
CLASS="LITERAL"
>database</TT
> and
<TT
CLASS="LITERAL"
>user</TT
> columns still apply.
This method should only be used when there is adequate
operating-system-level protection on connections to the server.
</P
><P
> <TT
CLASS="LITERAL"
>trust</TT
> authentication is appropriate and very
convenient for local connections on a single-user workstation. It
is usually <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>not</I
></SPAN
> appropriate by itself on a multiuser
machine. However, you might be able to use <TT
CLASS="LITERAL"
>trust</TT
> 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
<TT
CLASS="VARNAME"
>unix_socket_permissions</TT
> (and possibly
<TT
CLASS="VARNAME"
>unix_socket_group</TT
>) configuration parameters as
described in <A
HREF="runtime-config-connection.html"
>Section 18.3</A
>. Or you
could set the <TT
CLASS="VARNAME"
>unix_socket_directory</TT
>
configuration parameter to place the socket file in a suitably
restricted directory.
</P
><P
> 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 <TT
CLASS="LITERAL"
>host ... 127.0.0.1 ...</TT
> line from
<TT
CLASS="FILENAME"
>pg_hba.conf</TT
>, or change it to a
non-<TT
CLASS="LITERAL"
>trust</TT
> authentication method.
</P
><P
> <TT
CLASS="LITERAL"
>trust</TT
> 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 <TT
CLASS="FILENAME"
>pg_hba.conf</TT
> lines that specify
<TT
CLASS="LITERAL"
>trust</TT
>. It is seldom reasonable to use <TT
CLASS="LITERAL"
>trust</TT
>
for any TCP/IP connections other than those from <SPAN
CLASS="SYSTEMITEM"
>localhost</SPAN
> (127.0.0.1).
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AUTH-PASSWORD"
>19.3.2. Password authentication</A
></H2
><A
NAME="AEN28368"
></A
><A
NAME="AEN28370"
></A
><P
> The password-based authentication methods are <TT
CLASS="LITERAL"
>md5</TT
>
and <TT
CLASS="LITERAL"
>password</TT
>. These methods operate
similarly except for the way that the password is sent across the
connection: respectively, MD5-hashed and clear-text.
</P
><P
> If you are at all concerned about password
<SPAN
CLASS="QUOTE"
>"sniffing"</SPAN
> attacks then <TT
CLASS="LITERAL"
>md5</TT
> is preferred.
Plain <TT
CLASS="LITERAL"
>password</TT
> should always be avoided if possible.
However, <TT
CLASS="LITERAL"
>md5</TT
> cannot be used with the <A
HREF="runtime-config-connection.html#GUC-DB-USER-NAMESPACE"
>db_user_namespace</A
> feature. If the connection is
protected by SSL encryption then <TT
CLASS="LITERAL"
>password</TT
> can be used
safely (though SSL certificate authentication might be a better
choice if one is depending on using SSL).
</P
><P
> <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> database passwords are
separate from operating system user passwords. The password for
each database user is stored in the <TT
CLASS="LITERAL"
>pg_authid</TT
> system
catalog. Passwords can be managed with the SQL commands
<A
HREF="sql-createuser.html"
><I
>CREATE USER</I
></A
> and
<A
HREF="sql-alteruser.html"
><I
>ALTER USER</I
></A
>,
e.g., <KBD
CLASS="USERINPUT"
>CREATE USER foo WITH PASSWORD 'secret';</KBD
>.
By default, that is, if no password has been set up, the stored password
is null and password authentication will always fail for that user.
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="GSSAPI-AUTH"
>19.3.3. GSSAPI authentication</A
></H2
><A
NAME="AEN28391"
></A
><P
> <SPAN
CLASS="PRODUCTNAME"
>GSSAPI</SPAN
> is an industry-standard protocol
for secure authentication defined in RFC 2743.
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> supports
<SPAN
CLASS="PRODUCTNAME"
>GSSAPI</SPAN
> with <SPAN
CLASS="PRODUCTNAME"
>Kerberos</SPAN
>
authentication according to RFC 1964. <SPAN
CLASS="PRODUCTNAME"
>GSSAPI</SPAN
>
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 in clear unless
<ACRONYM
CLASS="ACRONYM"
>SSL</ACRONYM
> is used.
</P
><P
> When <SPAN
CLASS="PRODUCTNAME"
>GSSAPI</SPAN
> uses
<SPAN
CLASS="PRODUCTNAME"
>Kerberos</SPAN
>, it uses a standard principal
in the format
<TT
CLASS="LITERAL"
><TT
CLASS="REPLACEABLE"
><I
>servicename</I
></TT
>/<TT
CLASS="REPLACEABLE"
><I
>hostname</I
></TT
>@<TT
CLASS="REPLACEABLE"
><I
>realm</I
></TT
></TT
>. For information about the parts of the principal, and
how to set up the required keys, see <A
HREF="auth-methods.html#KERBEROS-AUTH"
>Section 19.3.5</A
>.
GSSAPI support has to be enabled when <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> is built;
see <A
HREF="installation.html"
>Chapter 15</A
> for more information.
</P
><P
> The following configuration options are supported for <SPAN
CLASS="PRODUCTNAME"
>GSSAPI</SPAN
>:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>map</TT
></DT
><DD
><P
> Allows for mapping between system and database usernames. See
<A
HREF="auth-username-maps.html"
>Section 19.2</A
> for details.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>include_realm</TT
></DT
><DD
><P
> If set to <TT
CLASS="LITERAL"
>1</TT
>, the realm name from the authenticated user
principal is included in the system user name that's passed through
username mapping (<A
HREF="auth-username-maps.html"
>Section 19.2</A
>). This is
useful for handling users from multiple realms.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>krb_realm</TT
></DT
><DD
><P
> 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 username mapping
is done.
</P
></DD
></DL
></DIV
><P>
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="SSPI-AUTH"
>19.3.4. SSPI authentication</A
></H2
><A
NAME="AEN28433"
></A
><P
> <SPAN
CLASS="PRODUCTNAME"
>SSPI</SPAN
> is a <SPAN
CLASS="PRODUCTNAME"
>Windows</SPAN
>
technology for secure authentication with single sign-on.
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> will use SSPI in
<TT
CLASS="LITERAL"
>negotiate</TT
> mode, which will use
<SPAN
CLASS="PRODUCTNAME"
>Kerberos</SPAN
> when possible and automatically
fall back to <SPAN
CLASS="PRODUCTNAME"
>NTLM</SPAN
> in other cases.
<SPAN
CLASS="PRODUCTNAME"
>SSPI</SPAN
> authentication only works when both
server and client are running <SPAN
CLASS="PRODUCTNAME"
>Windows</SPAN
>.
</P
><P
> When using <SPAN
CLASS="PRODUCTNAME"
>Kerberos</SPAN
> authentication,
<SPAN
CLASS="PRODUCTNAME"
>SSPI</SPAN
> works the same way
<SPAN
CLASS="PRODUCTNAME"
>GSSAPI</SPAN
> does. See <A
HREF="auth-methods.html#GSSAPI-AUTH"
>Section 19.3.3</A
>
for details.
</P
><P
> The following configuration options are supported for <SPAN
CLASS="PRODUCTNAME"
>SSPI</SPAN
>:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>map</TT
></DT
><DD
><P
> Allows for mapping between system and database usernames. See
<A
HREF="auth-username-maps.html"
>Section 19.2</A
> for details.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>include_realm</TT
></DT
><DD
><P
> If set to <TT
CLASS="LITERAL"
>1</TT
>, the realm name from the authenticated user
principal is included in the system user name that's passed through
username mapping (<A
HREF="auth-username-maps.html"
>Section 19.2</A
>). This is
useful for handling users from multiple realms.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>krb_realm</TT
></DT
><DD
><P
> 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 username mapping
is done.
</P
></DD
></DL
></DIV
><P>
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="KERBEROS-AUTH"
>19.3.5. Kerberos authentication</A
></H2
><A
NAME="AEN28472"
></A
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> 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 <SPAN
CLASS="PRODUCTNAME"
>GSSAPI</SPAN
>
authentication (see <A
HREF="auth-methods.html#GSSAPI-AUTH"
>Section 19.3.3</A
>) instead.
</P
></BLOCKQUOTE
></DIV
><P
> <SPAN
CLASS="PRODUCTNAME"
>Kerberos</SPAN
> is an industry-standard secure
authentication system suitable for distributed computing over a public
network. A description of the <SPAN
CLASS="PRODUCTNAME"
>Kerberos</SPAN
> system
is far beyond the scope of this document; in full generality it can be
quite complex (yet powerful). The
<A
HREF="http://www.nrl.navy.mil/CCS/people/kenh/kerberos-faq.html"
TARGET="_top"
> Kerberos <ACRONYM
CLASS="ACRONYM"
>FAQ</ACRONYM
></A
> or
<A
HREF="http://web.mit.edu/kerberos/www/"
TARGET="_top"
>MIT Kerberos page</A
>
can be good starting points for exploration.
Several sources for <SPAN
CLASS="PRODUCTNAME"
>Kerberos</SPAN
> distributions exist.
<SPAN
CLASS="PRODUCTNAME"
>Kerberos</SPAN
> provides secure authentication but
does not encrypt queries or data passed over the network; for that
use <ACRONYM
CLASS="ACRONYM"
>SSL</ACRONYM
>.
</P
><P
> <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> supports Kerberos version 5. Kerberos
support has to be enabled when <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> is built;
see <A
HREF="installation.html"
>Chapter 15</A
> for more information.
</P
><P
> <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> operates like a normal Kerberos service.
The name of the service principal is
<TT
CLASS="LITERAL"
><TT
CLASS="REPLACEABLE"
><I
>servicename</I
></TT
>/<TT
CLASS="REPLACEABLE"
><I
>hostname</I
></TT
>@<TT
CLASS="REPLACEABLE"
><I
>realm</I
></TT
></TT
>.
</P
><P
> <TT
CLASS="REPLACEABLE"
><I
>servicename</I
></TT
> can be set on the server side using the
<A
HREF="runtime-config-connection.html#GUC-KRB-SRVNAME"
>krb_srvname</A
> configuration parameter, and on the
client side using the <TT
CLASS="LITERAL"
>krbsrvname</TT
> connection parameter. (See
also <A
HREF="libpq-connect.html"
>Section 30.1</A
>.) The installation default can be
changed from the default <TT
CLASS="LITERAL"
>postgres</TT
> at build time using
<TT
CLASS="LITERAL"
>./configure --with-krb-srvnam=</TT
><TT
CLASS="REPLACEABLE"
><I
>whatever</I
></TT
>.
In most environments,
this parameter never needs to be changed. However, to support multiple
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> installations on the same host it is necessary.
Some Kerberos implementations might also require a different service name,
such as Microsoft Active Directory which requires the service name
to be in uppercase (<TT
CLASS="LITERAL"
>POSTGRES</TT
>).
</P
><P
> <TT
CLASS="REPLACEABLE"
><I
>hostname</I
></TT
> is the fully qualified host name of the
server machine. The service principal's realm is the preferred realm
of the server machine.
</P
><P
> Client principals must have their <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> database user
name as their first component, for example
<TT
CLASS="LITERAL"
>pgusername@realm</TT
>. Alternatively, you can use a username
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 <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>. If you have cross-realm
authentication enabled and need to verify the realm, use the
<TT
CLASS="LITERAL"
>krb_realm</TT
> parameter, or enable <TT
CLASS="LITERAL"
>include_realm</TT
>
and use username mapping to check the realm.
</P
><P
> Make sure that your server keytab file is readable (and preferably
only readable) by the <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> server
account. (See also <A
HREF="postgres-user.html"
>Section 17.1</A
>.) The location
of the key file is specified by the <A
HREF="runtime-config-connection.html#GUC-KRB-SERVER-KEYFILE"
>krb_server_keyfile</A
> configuration
parameter. The default is
<TT
CLASS="FILENAME"
>/usr/local/pgsql/etc/krb5.keytab</TT
> (or whichever
directory was specified as <TT
CLASS="VARNAME"
>sysconfdir</TT
> at build time).
</P
><P
> 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:
</P><PRE
CLASS="SCREEN"
><SAMP
CLASS="PROMPT"
>kadmin% </SAMP
><KBD
CLASS="USERINPUT"
>ank -randkey postgres/server.my.domain.org</KBD
>
<SAMP
CLASS="PROMPT"
>kadmin% </SAMP
><KBD
CLASS="USERINPUT"
>ktadd -k krb5.keytab postgres/server.my.domain.org</KBD
></PRE
><P>
</P
><P
> 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 <TT
CLASS="LITERAL"
>fred</TT
>, both principal
<TT
CLASS="LITERAL"
>fred@EXAMPLE.COM</TT
> and
<TT
CLASS="LITERAL"
>fred/users.example.com@EXAMPLE.COM</TT
> could be used to
authenticate to the database server.
</P
><P
> If you use <A
HREF="http://modauthkerb.sf.net"
TARGET="_top"
> <SPAN
CLASS="APPLICATION"
>mod_auth_kerb</SPAN
></A
>
and <SPAN
CLASS="APPLICATION"
>mod_perl</SPAN
> on your
<SPAN
CLASS="PRODUCTNAME"
>Apache</SPAN
> web server, you can use
<TT
CLASS="LITERAL"
>AuthType KerberosV5SaveCredentials</TT
> with a
<SPAN
CLASS="APPLICATION"
>mod_perl</SPAN
> script. This gives secure
database access over the web, no extra passwords required.
</P
><P
> The following configuration options are supported for
<SPAN
CLASS="PRODUCTNAME"
>Kerberos</SPAN
>:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>map</TT
></DT
><DD
><P
> Allows for mapping between system and database usernames. See
<A
HREF="auth-username-maps.html"
>Section 19.2</A
> for details.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>include_realm</TT
></DT
><DD
><P
> If set to <TT
CLASS="LITERAL"
>1</TT
>, the realm name from the authenticated user
principal is included in the system user name that's passed through
username mapping (<A
HREF="auth-username-maps.html"
>Section 19.2</A
>). This is
useful for handling users from multiple realms.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>krb_realm</TT
></DT
><DD
><P
> 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 username mapping
is done.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>krb_server_hostname</TT
></DT
><DD
><P
> Sets the host name part of the service principal.
This, combined with <TT
CLASS="VARNAME"
>krb_srvname</TT
>, is used to generate
the complete service principal, that is
<TT
CLASS="VARNAME"
>krb_srvname</TT
><TT
CLASS="LITERAL"
>/</TT
><TT
CLASS="VARNAME"
>krb_server_hostname</TT
><TT
CLASS="LITERAL"
>@</TT
>REALM.
If not set, the default is the server host name.
</P
></DD
></DL
></DIV
><P>
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AUTH-IDENT"
>19.3.6. Ident-based authentication</A
></H2
><A
NAME="AEN28571"
></A
><P
> The ident authentication method works by obtaining the client's
operating system user name and using it as the allowed database user
name (with an optional username mapping).
The determination of the client's
user name is the security-critical point, and it works differently
depending on the connection type.
</P
><P
> The following configuration options are supported for <SPAN
CLASS="PRODUCTNAME"
>ident</SPAN
>:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>map</TT
></DT
><DD
><P
> Allows for mapping between system and database usernames. See
<A
HREF="auth-username-maps.html"
>Section 19.2</A
> for details.
</P
></DD
></DL
></DIV
><P>
</P
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN28583"
>19.3.6.1. Ident Authentication over TCP/IP</A
></H3
><P
> The <SPAN
CLASS="QUOTE"
>"Identification Protocol"</SPAN
> is described in
RFC 1413. Virtually every Unix-like
operating system ships with an ident server that listens on TCP
port 113 by default. The basic functionality of an ident server
is to answer questions like <SPAN
CLASS="QUOTE"
>"What user initiated the
connection that goes out of your port <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
>
and connects to my port <TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
>?"</SPAN
>.
Since <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> knows both <TT
CLASS="REPLACEABLE"
><I
>X</I
></TT
> and
<TT
CLASS="REPLACEABLE"
><I
>Y</I
></TT
> when a physical connection is established, it
can interrogate the ident server on the host of the connecting
client and could theoretically determine the operating system user
for any given connection this way.
</P
><P
> The drawback of this procedure is that it depends on the integrity
of the client: if the client machine is untrusted or compromised
an attacker could run just about any program on port 113 and
return any user name 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:
<A
NAME="AEN28594"
></A
><TABLE
BORDER="0"
WIDTH="100%"
CELLSPACING="0"
CELLPADDING="0"
CLASS="BLOCKQUOTE"
><TR
><TD
WIDTH="10%"
VALIGN="TOP"
> </TD
><TD
VALIGN="TOP"
><P
> The Identification Protocol is not intended as an authorization
or access control protocol.
</P
></TD
><TD
WIDTH="10%"
VALIGN="TOP"
> </TD
></TR
><TR
><TD
COLSPAN="2"
ALIGN="RIGHT"
VALIGN="TOP"
>--<SPAN
CLASS="ATTRIBUTION"
>RFC 1413</SPAN
></TD
><TD
WIDTH="10%"
> </TD
></TR
></TABLE
>
</P
><P
> Some ident servers have a nonstandard option that causes the returned
user name to be encrypted, using a key that only the originating
machine's administrator knows. This option <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>must not</I
></SPAN
> be
used when using the ident server with <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>,
since <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> does not have any way to decrypt the
returned string to determine the actual user name.
</P
></DIV
><DIV
CLASS="SECT3"
><H3
CLASS="SECT3"
><A
NAME="AEN28601"
>19.3.6.2. Ident Authentication over Local Sockets</A
></H3
><P
> On systems supporting <TT
CLASS="SYMBOL"
>SO_PEERCRED</TT
> requests for
Unix-domain sockets (currently <SPAN
CLASS="SYSTEMITEM"
>Linux</SPAN
>, <SPAN
CLASS="SYSTEMITEM"
>FreeBSD</SPAN
>,
<SPAN
CLASS="SYSTEMITEM"
>NetBSD</SPAN
>, <SPAN
CLASS="SYSTEMITEM"
>OpenBSD</SPAN
>,
<SPAN
CLASS="SYSTEMITEM"
>BSD/OS</SPAN
>, and <SPAN
CLASS="SYSTEMITEM"
>Solaris</SPAN
>), ident authentication can also
be applied to local connections. In this case, no security risk is added by
using ident authentication; indeed it is a preferable choice for
local connections on such systems.
</P
><P
> On systems without <TT
CLASS="SYMBOL"
>SO_PEERCRED</TT
> requests, ident
authentication is only available for TCP/IP connections. As a
work-around, it is possible to specify the <SPAN
CLASS="SYSTEMITEM"
>localhost</SPAN
> address <SPAN
CLASS="SYSTEMITEM"
>127.0.0.1</SPAN
> and make connections to this
address. This method is trustworthy to the extent that you trust
the local ident server.
</P
></DIV
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AUTH-LDAP"
>19.3.7. LDAP authentication</A
></H2
><A
NAME="AEN28617"
></A
><P
> This authentication method operates similarly to
<TT
CLASS="LITERAL"
>password</TT
> 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.
</P
><P
> The server will bind to the distinguished name constructed as
<TT
CLASS="REPLACEABLE"
><I
>prefix</I
></TT
> <TT
CLASS="REPLACEABLE"
><I
>username</I
></TT
> <TT
CLASS="REPLACEABLE"
><I
>suffix</I
></TT
>.
Typically, the <TT
CLASS="REPLACEABLE"
><I
>prefix</I
></TT
> parameter is used to specify
<TT
CLASS="LITERAL"
>cn=</TT
>, or <TT
CLASS="REPLACEABLE"
><I
>DOMAIN</I
></TT
><TT
CLASS="LITERAL"
>\</TT
> in an Active
Directory environment. <TT
CLASS="REPLACEABLE"
><I
>suffix</I
></TT
> is used to specify the
remaining part of the DN in a non-Active Directory environment.
</P
><P
> The following configuration options are supported for LDAP:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>ldapserver</TT
></DT
><DD
><P
> Names or IP addresses of LDAP servers to connect to. Multiple
servers may be specified, separated by spaces.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>ldapprefix</TT
></DT
><DD
><P
> String to prepend to the username when forming the DN to bind as.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>ldapsuffix</TT
></DT
><DD
><P
> String to append to the username when forming the DN to bind as.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>ldapport</TT
></DT
><DD
><P
> Port number on LDAP server to connect to. If no port is specified,
the default port in the LDAP library will be used.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>ldaptls</TT
></DT
><DD
><P
> Set to <TT
CLASS="LITERAL"
>1</TT
> 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.
</P
></DD
></DL
></DIV
><P>
</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> 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:
</P
></BLOCKQUOTE
></DIV
><PRE
CLASS="SYNOPSIS"
>ldapserver=ldap.example.net ldapprefix="cn=" ldapsuffix=", dc=example, dc=net"
</PRE
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AUTH-CERT"
>19.3.8. Certificate authentication</A
></H2
><A
NAME="AEN28663"
></A
><P
> 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 <TT
CLASS="LITERAL"
>cn</TT
> attribute of the certificate
will be compared to the requested database username, and if they match
the login will be allowed. Username mapping can be used to allow
<TT
CLASS="LITERAL"
>cn</TT
> to be different from the database username.
</P
><P
> The following configuration options are supported for SSL certificate
authentication:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>map</TT
></DT
><DD
><P
> Allows for mapping between system and database usernames. See
<A
HREF="auth-username-maps.html"
>Section 19.2</A
> for details.
</P
></DD
></DL
></DIV
><P>
</P
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AUTH-PAM"
>19.3.9. PAM authentication</A
></H2
><A
NAME="AEN28678"
></A
><P
> This authentication method operates similarly to
<TT
CLASS="LITERAL"
>password</TT
> except that it uses PAM (Pluggable
Authentication Modules) as the authentication mechanism. The
default PAM service name is <TT
CLASS="LITERAL"
>postgresql</TT
>.
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 <A
HREF="http://www.kernel.org/pub/linux/libs/pam/"
TARGET="_top"
> <SPAN
CLASS="PRODUCTNAME"
>Linux-PAM</SPAN
> Page</A
>
and the <A
HREF="http://www.sun.com/software/solaris/pam/"
TARGET="_top"
> <SPAN
CLASS="SYSTEMITEM"
>Solaris</SPAN
> PAM Page</A
>.
</P
><P
> The following configuration options are supported for PAM:
<P
></P
></P><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="LITERAL"
>pamservice</TT
></DT
><DD
><P
> PAM service name.
</P
></DD
></DL
></DIV
><P>
</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> If PAM is set up to read <TT
CLASS="FILENAME"
>/etc/shadow</TT
>, 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.
</P
></BLOCKQUOTE
></DIV
></DIV
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