<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Authentication methods</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REV="MADE" HREF="mailto:pgsql-docs@postgresql.org"><LINK REL="HOME" TITLE="PostgreSQL 8.4.12 Documentation" HREF="index.html"><LINK REL="UP" TITLE="Client Authentication" HREF="client-authentication.html"><LINK REL="PREVIOUS" TITLE="Username maps" HREF="auth-username-maps.html"><LINK REL="NEXT" TITLE="Authentication problems" HREF="client-authentication-problems.html"><LINK REL="STYLESHEET" TYPE="text/css" HREF="stylesheet.css"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"><META NAME="creation" CONTENT="2012-05-31T23:30:11"></HEAD ><BODY CLASS="SECT1" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="5" ALIGN="center" VALIGN="bottom" >PostgreSQL 8.4.12 Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="auth-username-maps.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="client-authentication.html" >Fast Backward</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 19. Client Authentication</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="client-authentication.html" >Fast Forward</A ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="client-authentication-problems.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><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="AEN28340" ></A ><A NAME="AEN28342" ></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="AEN28363" ></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="AEN28405" ></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="AEN28444" ></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="AEN28543" ></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="AEN28555" >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="AEN28566" ></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="AEN28573" >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="AEN28589" ></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="AEN28635" ></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="AEN28650" ></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 ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="auth-username-maps.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="client-authentication-problems.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Username maps</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="client-authentication.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Authentication problems</TD ></TR ></TABLE ></DIV ></BODY ></HTML >