Rename ident authentication over local connections to peer

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.

Author: mhagander

doc/src/sgml/client-auth.sgml

@@ -457,16 +457,29 @@ hostnossl  <replaceable>database</replaceable>  <replaceable>user</replaceable>
         <term><literal>ident</></term>
         <listitem>
          <para>
-          Obtain the operating system user name of the client (for
-          TCP/IP connections by contacting the ident server on the
-          client, for local connections by getting it from the
-          operating system) and check if it matches the requested
-          database user name.
+          Obtain the operating system user name of the client
+          by contacting the ident server on the client
+          and check if it matches the requested database user name.
+          Ident authentication can only be used on TCP/IP
+          connections. When specified for local connections, peer
+          authentication will be used instead.
           See <xref linkend="auth-ident"> for details.
          </para>
         </listitem>
        </varlistentry>
 
+       <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>
@@ -1200,21 +1213,27 @@ omicron         bryanh                  guest1
   </sect2>
 
   <sect2 id="auth-ident">
-   <title>Ident-based Authentication</title>
+   <title>Ident Authentication</title>
 
    <indexterm>
     <primary>ident</primary>
    </indexterm>
 
    <para>
     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 user name mapping).
-    The determination of the client's
-    user name is the security-critical point, and it works differently
-    depending on the connection type, as described below.
+    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>
@@ -1230,9 +1249,6 @@ omicron         bryanh                  guest1
     </variablelist>
    </para>
 
-   <sect3>
-    <title>Ident Authentication Over TCP/IP</title>
-
    <para>
     The <quote>Identification Protocol</quote> is described in
     RFC 1413. Virtually every Unix-like
@@ -1275,36 +1291,48 @@ omicron         bryanh                  guest1
     since <productname>PostgreSQL</> does not have any way to decrypt the
     returned string to determine the actual user name.
    </para>
-   </sect3>
+  </sect2>
 
-   <sect3>
-    <title>Ident Authentication Over Local Sockets</title>
+  <sect2 id="auth-peer">
+   <title>Peer Authentication</title>
+
+   <indexterm>
+    <primary>peer</primary>
+   </indexterm>
 
    <para>
-    On systems supporting <symbol>SO_PEERCRED</symbol> requests for
+    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>), ident authentication can also
-    be applied to local connections.
+    <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.
-    In this case, no security risk is added by
-    using ident authentication; indeed it is a preferable choice for
-    local connections on such systems.
    </para>
 
-    <para>
-     On systems without <symbol>SO_PEERCRED</> requests, ident
-     authentication is only available for TCP/IP connections. As a
-     work-around, it is possible to specify the <systemitem
-     class="systemname">localhost</> address <systemitem
-     class="systemname">127.0.0.1</> and make connections to this
-     address.  This method is trustworthy to the extent that you trust
-     the local ident server.
-    </para>
-    </sect3>
-
   </sect2>
 
   <sect2 id="auth-ldap">

doc/src/sgml/runtime.sgml

@@ -148,7 +148,7 @@ postgres$ <userinput>initdb -D /usr/local/pgsql/data</userinput>
    mode is not used; or modify the generated <filename>pg_hba.conf</filename>
    file after running <command>initdb</command>, but
    <emphasis>before</> you start the server for the first time. (Other
-   reasonable approaches include using <literal>ident</literal> authentication
+   reasonable approaches include using <literal>peer</literal> authentication
    or file system permissions to restrict connections. See <xref
    linkend="client-authentication"> for more information.)
   </para>