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Expand on description of when to use or not use TRUST auth method.

This commit is contained in:
Tom Lane 2001-12-27 21:37:34 +00:00
parent 9935a85fa4
commit 6f0f5bf2fb
2 changed files with 89 additions and 18 deletions
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64
doc/src/sgml/client-auth.sgml
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@ -1,4 +1,6 @@
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/client-auth.sgml,v 1.30 2001/11/28 20:49:09 petere Exp $ -->
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/client-auth.sgml,v 1.31 2001/12/27 21:37:34 tgl Exp $
-->
<chapter id="client-authentication">
<title>Client Authentication</title>
@ -437,9 +439,53 @@ local all md5 admins
<sect1 id="auth-methods">
<title>Authentication methods</title>
<para>
The following describes the authentication methods in detail.
The following describes 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 postmaster is authorized to access the database as
whatever database user he specifies (including the database superuser).
This method should only be used when there is adequate system-level
protection on connections to the postmaster port.
</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 multi-user machine.
However, you may be able to use <literal>trust</> even on a multi-user
machine, if you restrict access to the postmaster's socket file using
filesystem permissions. To do this, set the parameter
<varname>unix_socket_permissions</varname> (and possibly
<varname>unix_socket_group</varname>) in <filename>postgresql.conf</>,
as described in <xref linkend="runtime-config-general">. Or you could
set <varname>unix_socket_directory</varname> to place the socket file
in a suitably restricted directory.
</para>
<para>
Setting filesystem permissions only helps for Unix-socket connections.
Local TCP connections are not restricted by it; therefore, if you want
to use 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 connections
if you trust every user on every machine that is allowed to connect
to the postmaster by the <filename>pg_hba.conf</> lines that specify
<literal>trust</>. It is seldom reasonable to use <literal>trust</>
for any TCP connections other than those from localhost (127.0.0.1).
</para>
</sect2>
<sect2 id="auth-password">
<title>Password authentication</title>
@ -450,6 +496,18 @@ local all md5 admins
<primary>MD5</>
</indexterm>
<para>
Password-based authentication methods include <literal>md5</>,
<literal>crypt</>, and <literal>password</>. These methods operate
similarly except for the way that the password is sent across the
connection. If you are at all concerned about password <quote>sniffing</>
attacks then <literal>md5</> is preferred, with <literal>crypt</> a
second choice if you must support obsolete clients. Plain
<literal>password</> should especially be avoided for connections over
the open Internet (unless you use SSL, SSH, or other communications
security wrappers around the connection).
</para>
<para>
<productname>PostgreSQL</productname> database passwords are separate from
operating system user passwords. Ordinarily, the password for each
@ -652,7 +710,7 @@ local all md5 admins
On systems supporting <symbol>SO_PEERCRED</symbol> requests for Unix-domain sockets,
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 such a system.
it is a preferable choice for local connections on such a system.
</para>
<para>

43
doc/src/sgml/runtime.sgml
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@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.99 2001/11/28 20:49:10 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.100 2001/12/27 21:37:34 tgl Exp $
-->
<Chapter Id="runtime">
@ -57,7 +57,7 @@ $Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.99 2001/11/28 20:49:10 pet
through a single instance of a running database server. After
initialization, a database cluster will contain one database named
<literal>template1</literal>. As the name suggests, this will be used
as a template for any subsequently created database; it should not be
as a template for subsequently created databases; it should not be
used for actual work.
</para>
@ -65,7 +65,7 @@ $Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.99 2001/11/28 20:49:10 pet
In file system terms, a database cluster will be a single directory
under which all data will be stored. We call this the <firstterm>data
directory</firstterm> or <firstterm>data area</firstterm>. It is
completely up to you where you choose to store your data, there is no
completely up to you where you choose to store your data. There is no
default, although locations such as
<filename>/usr/local/pgsql/data</filename> or
<filename>/var/lib/pgsql/data</filename> are popular. To initialize a
@ -76,7 +76,7 @@ $Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.99 2001/11/28 20:49:10 pet
<screen>
<prompt>$</> <userinput>initdb -D /usr/local/pgsql/data</userinput>
</screen>
Note that you must execute this command while being logged in to
Note that you must execute this command while being logged into
the <productname>PostgreSQL</productname> user account, which is described in the previous
section.
</para>
@ -113,22 +113,25 @@ postgres$ <userinput>initdb -D /usr/local/pgsql/data</userinput>
<para>
Because the data directory contains all the data stored in the
database it is essential that it be well secured from unauthorized
database, it is essential that it be well secured from unauthorized
access. <command>initdb</command> therefore revokes access
permissions from everyone but the <productname>PostgreSQL</productname> user account.
</para>
<para>
However, while the directory contents are secure, the default
<filename>pg_hba.conf</filename> authentication of
<literal>trust</literal> allows any local user to become the
superuser and connect to the database. If you don't trust your local
users, we recommend you use the <command>initdb</command> option
<filename>pg_hba.conf</filename> authentication method of
<literal>trust</literal> allows any local user to connect to the database
and even become the database superuser. If you don't trust other local
users, we recommend you use <command>initdb</command>'s option
<option>-W</option> or <option>--pwprompt</option> to assign a
password to the superuser and modify your
<filename>pg_hba.conf</filename> accordingly. (Another option:
Your operating system may support <literal>ident</literal> for
local connections.)
password to the database superuser. After <command>initdb</command>,
modify <filename>pg_hba.conf</filename> to use <literal>md5</> or
<literal>password</>, instead of <literal>trust</>, authentication
<emphasis>before</> you first start the postmaster. (Other, possibly
more convenient approaches include using <literal>ident</literal>
authentication or filesystem permissions to restrict connections. See
<xref linkend="client-authentication"> for more information.)
</para>
<para>
@ -172,7 +175,7 @@ NOTICE: Initializing database with en_US collation order.
$ <userinput>postmaster -D /usr/local/pgsql/data</userinput>
</screen>
which will leave the server running in the foreground. This must
again be done while logged in to the <productname>PostgreSQL</productname> user account. Without
again be done while logged into the <productname>PostgreSQL</productname> user account. Without
a <option>-D</option>, the server will try to use the data
directory in the environment variable <envar>PGDATA</envar>; if
neither of these works it will fail.
@ -2287,7 +2290,7 @@ default:\
<para>
On <productname>Linux</productname>
<filename>/proc/sys/fs/file-max</filename> determines the
maximum number of files that the kernel will allocate. It can
maximum number of open files that the kernel will support. It can
be changed by writing a different number into the file or by
adding an assignment in <filename>/etc/sysctl.conf</filename>.
The maximum limit of files per process is fixed at the time the
@ -2315,6 +2318,16 @@ default:\
is perhaps what you want, but on dedicated servers you may want to
raise this limit.
</para>
<para>
On the other side of the coin, some systems allow individual
processes to open large numbers of files; if more than a few processes
do so then the system-wide limit can easily be exceeded. If you find
this happening, and don't want to alter the system-wide limit, you
can set <productname>PostgreSQL</productname>'s
<varname>max_files_per_process</varname> configuration parameter
to limit its consumption of open files.
</para>
</sect2>
</sect1>