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提交 2c0edb3c 编写于 作者: P Peter Eisentraut
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Separated set constraints and set transaction reference pages, revised set 

reference page to new configuration system. Big update to administrator's
guide, chapters Runtime environment, Client authentication, and User
management, the latter two were part of the old Security chapter.
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doc/src/sgml/Makefile
浏览文件 @ 2c0edb3c
......@@ -8,7 +8,7 @@
#
#
# IDENTIFICATION
# $Header: /cvsroot/pgsql/doc/src/sgml/Makefile,v 1.14 2000/05/02 20:01:51 thomas Exp $
# $Header: /cvsroot/pgsql/doc/src/sgml/Makefile,v 1.15 2000/06/18 21:24:51 petere Exp $
#
#----------------------------------------------------------------------------
......@@ -104,7 +104,7 @@ COMMANDS= abort.sgml alter_group.sgml alter_table.sgml alter_user.sgml \
insert.sgml listen.sgml load.sgml lock.sgml move.sgml \
notify.sgml \
reindex.sgml reset.sgml revoke.sgml rollback.sgml \
select.sgml select_into.sgml set.sgml show.sgml \
select.sgml select_into.sgml set.sgml set_constraints.sgml set_transaction.sgml show.sgml \
truncate.sgml unlisten.sgml update.sgml vacuum.sgml
FUNCTIONS= current_date.sgml current_time.sgml current_timestamp.sgml current_user.sgml
......
doc/src/sgml/admin.sgml
浏览文件 @ 2c0edb3c
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/Attic/admin.sgml,v 1.22 2000/05/02 20:01:51 thomas Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/Attic/admin.sgml,v 1.23 2000/06/18 21:24:51 petere Exp $
Postgres Administrator's Guide.
Derived from postgres.sgml.
......@@ -27,7 +27,8 @@ Derived from postgres.sgml.
<!entity regress SYSTEM "regress.sgml">
<!entity release SYSTEM "release.sgml">
<!entity runtime SYSTEM "runtime.sgml">
<!entity security SYSTEM "security.sgml">
<!entity client-auth SYSTEM "client-auth.sgml">
<!entity user-manag SYSTEM "user-manag.sgml">
<!entity start-ag SYSTEM "start-ag.sgml">
<!entity trouble SYSTEM "trouble.sgml">
......@@ -111,10 +112,10 @@ Your name here...
&install;
&installw;
&runtime;
&security;
&client-auth;
&user-manag;
&start-ag;
&manage-ag;
&trouble;
&recovery;
&regress;
&release;
......
doc/src/sgml/client-auth.sgml 0 → 100644
浏览文件 @ 2c0edb3c
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/client-auth.sgml,v 1.1 2000/06/18 21:24:51 petere Exp $ -->
<chapter id="client-authentication">
<title>Client Authentication</title>
<para>
User names from the operating system and from a
<productname>Postgres</productname> database installation are
logically separate. When a client application connects, it specifies
which database user name it wants to connect as, similar to how one
logs into a Unix computer. Within the SQL environment the active
database user name determines various access privileges to database
objects -- see <xref linkend="user-manag"> for more information
about that. It is therefore obviously essential to restrict what
database user name a given client can connect as.
</para>
<para>
<firstterm>Authentication</firstterm> is the process by which the
database server establishes the identity of the client, and by
extension determines whether the client application (or the user
which runs the client application) is permitted to connect with the
user name that was requested.
</para>
<para>
<productname>Postgres</productname> offers client authentication by
(client) host and by database, with a number of different
authentication methods available.
</para>
<sect1 id="pg-hba.conf">
<title>The <filename>pg_hba.conf</filename> file</title>
<para>
Client authentication is controlled by the file
<filename>pg_hba.conf</filename> in the data directory, e.g.,
<filename>/usr/local/pgsql/data/pg_hba.conf</filename>. (HBA =
host-based authentication) A default file is installed when the
data area is initialized by <application>initdb</application>.
</para>
<para>
The general format of the <filename>pg_hba.conf</filename> file is
of a set of records, one per line. Blank lines and lines beginning
with a hash character (<quote>#</quote>) are ignored. A record is
made up of a number of fields which are separated by spaces and/or
tabs.
</para>
<para>
A record may have one of the two formats
<synopsis>
local <replaceable>database</replaceable> <replaceable>authentication-method</replaceable> [ <replaceable>authentication-option</replaceable> ]
host <replaceable>database</replaceable> <replaceable>IP-address</replaceable> <replaceable>IP-mask</replaceable> <replaceable>authentication-method</replaceable> [ <replaceable>authentication-option</replaceable> ]
</synopsis>
The meaning of the fields is as follows:
<variablelist>
<varlistentry>
<term><literal>local</literal></term>
<listitem>
<para>
This record pertains to connection attempts over Unix domain
sockets.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>host</literal></term>
<listitem>
<para>
This record pertains to connection attempts over TCP/IP
networks. Note that TCP/IP connections are completely disabled
unless the server is started with the <option>-i</option> or
the equivalent configuration parameter is set.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>database</replaceable></term>
<listitem>
<para>
Specifies the database that this record applies to. The value
<literal>all</literal> specifies that it applies to all
databases.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>IP address</replaceable></term>
<term><replaceable>IP mask</replaceable></term>
<listitem>
<para>
These two fields control to which hosts a
<literal>host</literal> record applies, based on their IP
address. (Of course IP addresses can be spoofed but this
consideration is beyond the scope of
<productname>Postgres</productname>.) The precise logic is that
<blockquote>
<informalfigure>
<programlisting>(<replaceable>actual-IP-address</replaceable> xor <replaceable>IP-address-field</replaceable>) and <replaceable>IP-mask-field</replaceable></programlisting>
</informalfigure>
</blockquote>
must be zero for the record to match.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>authentication method</replaceable></term>
<listitem>
<para>
Specifies the method a user must use to authenticate themselves
when connecting to that database.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>authentication option</replaceable></term>
<listitem>
<para>
This field is interpreted differently depending on the
authentication method.
</para>
</listitem>
</varlistentry>
</variablelist>
The first record that matches a connection attempt is used. Note
that there is no <quote>fall-through</quote> or
<quote>backup</quote>, that is, if one record is chosen and the
authentication fails, the following records are not considered. If
no record matches, the access will be denied.
</para>
<para>
The <filename>pg_hba.conf</filename> file is re-read before each
connection attempt. It is therefore easily possible to modify
access permissions while the server is running.
</para>
<para>
An example of a <filename>pg_hba.conf</filename> file is shown in
<xref linkend="example-pg-hba.conf">. See below for details on the
different authentication methods.
<example id="example-pg-hba.conf">
<title>An example <filename>pg_hba.conf</filename> file</title>
<programlisting>
# Trust any connection via Unix domain sockets.
local trust
# Trust any connection via TCP/IP from this machine.
host all 127.0.0.1 255.255.255.255 trust
# We don't like this machine.
host all 192.168.0.10 255.255.255.0 reject
# This machine can't encrypt so we ask for passwords in clear.
host all 192.168.0.3 255.255.255.0 password
# The rest of this group of machines should provide encrypted passwords.
host all 192.168.0.0 255.255.255.0 crypt
# Authenticate these networks using ident
host all 192.168.1.0 255.255.255.0 ident usermap
host all 192.168.2.0 255.255.255.0 ident othermap
</programlisting>
</example>
</para>
</sect1>
<sect1 id="auth-methods">
<title>Authentication methods</title>
<para>
The following authentication methods are supported. They are
descibed in detail below.
<variablelist>
<varlistentry>
<term>trust</term>
<listitem>
<para>
The connection is allowed unconditionally. This method allows
any user that has login access to the client host to connect as
any user whatsoever. Use with care.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>reject</term>
<listitem>
<para>
The connection is rejected unconditionally. This is mostly
useful to <quote>filter out</quote> certain hosts from a group.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>password</term>
<listitem>
<para>
The client is required to supply a password for the connection
attempt which is required to match the password that was set up
for the user. (These passwords are separate from any operating
sytem password.)
</para>
<para>
An optional password file may be specified after the
<literal>password</literal> keyword to obtain the password from
that file rather than the pg_shadow system catalog.
</para>
<para>
The password is sent over the wire in clear text. For better
protection, use the <literal>crypt</literal> method.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>crypt</term>
<listitem>
<para>
Like the <literal>password</literal> method, but the password
is sent over the wire encrypted using a simple
challenge-response protocol. Note that this is still not
cryptographically secure but it protects against incidental
wire-sniffing. Interestingly enough, the
<literal>crypt</literal> does not support secondary password
files.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>krb4</term>
<listitem>
<para>
Kerberos V4 is used to authenticate the user. This is only
available for TCP/IP connections.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>krb5</term>
<listitem>
<para>
Kerberos V5 is used to authenticate the user. This is only
available for TCP/IP connections.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>ident</term>
<listitem>
<para>
The ident server on the client host is asked for the identity
of the connecting user. <productname>Postgres</productname>
then verifies whether the so identified operating system user
is allowed to connect as the database user that is requested.
The <replaceable>authentication option</replaceable> following
the <literal>ident</> keyword specifies the name of an
<firstterm>ident map</firstterm> that specifies which operating
system users equate with which database users. See below for
details.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<sect2>
<title>Password authentication</title>
<para>
Ordinarily, the password for each database user is stored in the
pg_shadow system catalog table. Passwords can be managed with the
query language commands <command>CREATE USER</command> and
<command>ALTER USER</command>, e.g., <userinput>CREATE USER foo
WITH PASSWORD 'secret';</userinput>. By default, that is, if no
password has explicitly been set up, the stored password is
<quote>NULL</quote> and password authentication will always fail
for that user.
</para>
<para>
Secondary password files can be used if a given set of passwords
should only apply to a particular database or set thereof.
Secondary password files have a format similar to the standard
Unix password file <filename>/etc/passwd</filename>, that is,
<synopsis>
<replaceable>username</replaceable>:<replaceable>password</replaceable>
</synopsis>
Any extra colon separated fields following the password are
ignored. The password is expected to be encrypted using the
system's <function>crypt()</function> function. The utility
program <application>pg_passwd</application> that is installed
with <productname>Postgres</productname> can be used to manage
these password files.
</para>
<para>
Secondary password files can also be used to restrict certain
users from connecting to certain databases at all. This is
currently not possible to achieve using the normal password
mechanism (because users and passwords are global across all
databases). If a user is not listed in the applicable password
file the connection will be refused.
</para>
<para>
Note that using secondary password files means that one can no
longer use <command>ALTER USER</command> to change one's password.
It will still appear to work but the password one is actually
changing is not the password that the system will end up using.
</para>
</sect2>
<sect2>
<title>Kerberos authentication</title>
<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 far beyond the scope
of this document; in all generality it can be quite complex. The
<ulink url="http://www.nrl.navy.mil/CCS/people/kenh/kerberos-faq.html">Kerberos <acronym>FAQ</></ulink>
can be a good starting point for exploration.
</para>
<para>
In order to use <productname>Kerberos</>, support for it must be
enable at build time. Both Kerberos 4 and 5 are supported.
</para>
<para>
<productname>Postgres</> should operate like a normal Kerberos
service. The name of the service principal is normally
<literal>postgres</literal>, unless it was changed during the
build. Make sure that your server keytab file is readable (and
preferrably only readable) by the Postgres server account (see
<xref linkend="postgres-user">). The location of the keytab file
is specified at build time. By default it is
<filename>/etc/srvtab</filename> in Kerberos 4 and
<filename>FILE:/usr/local/postgres/krb5.keytab</filename> in
Kerberos 5.
</para>
<!-- Note from Peter E.: Some of the Kerberos usage information is
still in config.sgml and some in doc/README.kerberos. It should be
integrated here. -->
</sect2>
<sect2>
<title>Ident-based authentication</title>
<para>
The <quote>Identification Protocol</quote> is described in
<citetitle>RFC 1413</citetitle>. Virtually every Unix-like
operating systems ships with an ident server that listens on TCP
port 113 by default. The basic functionality of the 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 both <replaceable>X</replaceable> and
<replaceable>Y</replaceable> are known,
<productname>Postgres</productname> could theoretically determine
the operating system user for any given connection this way.
</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. 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>
When using ident-based authentication, after having determined the
operating system user that initiated the connection,
<productname>Postgres</productname> determines as what database
system user he may connect. This is controlled by the ident map
argument that follows the <literal>ident</> keyword in the
<filename>pg_hba.conf</filename> file. The simplest ident map is
<literal>sameuser</literal>, which allows any operating system
user to connect as the database user of the same name (if the
latter exists). Other maps must be created manually.
</para>
<para>
Ident maps are held in the file <filename>pg_ident.conf</filename>
in the data directory, which contains lines of the general form:
<synopsis>
<replaceable>map-name</> <replaceable>ident-username</> <replaceable>database-username</>
</synopsis>
Comments and whitespace are handled in the usual way.
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 which operating system user is
allowed to connect as which database user. The same
<replaceable>map-name</> can be used repeatedly to specify more
user-mappings. There is also no restriction regarding how many
database users a given operating system may correspond to and vice
versa.
</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 that example setup, anyone
logged in to a machine on the 192.168.1 network that does not have
the a user name joe, robert, or ann would not be granted access.
Unix user robert would only be allowed access when he tries to
connect as <quote>bob</quote>, not as <quote>robert</quote> or
anyone else. <quote>ann</quote> and <quote>joe</quote> would only
be allowed to connect <quote>as themselves</quote>. On the
192.168.2 network, however, a user <quote>ann</quote> would not be
allowed to connect at all, only the user <quote>bob</> can connect
as <quote>bob</> and some user <quote>karl</> can connect as
<quote>joe</> as well.
</para>
<example id="example-pg-ident.conf">
<title>An example <filename>pg_ident.conf</> file</title>
<programlisting>
usermap joe joe
# bob has username robert on these machines
usermap robert bob
usermap ann ann
othermap joe joe
othermap bob bob
othermap karl joe
</programlisting>
</example>
</sect2>
</sect1>
<sect1 id="client-authentication-problems">
<title>Authentication problems</title>
<para>
Genuine authentication failures and related problems generally
manifest themselves through error messages like the following.
</para>
<para>
<ProgramListing>
No pg_hba.conf entry for host 123.123.123.123, user joeblow, database testdb
</ProgramListing>
This is what you are most likely to get if you succeed in
contacting the server, but it doesn't want to talk to you. As the
message suggests, the server refused the connection request
because it found no authorizing entry in its <filename>pg_hba.conf</filename>
configuration file.
</para>
<para>
<ProgramListing>
Password authentication failed for user 'joeblow'
</ProgramListing>
Messages like this indicate that you contacted the server, and
it's 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're
providing, or check your Kerberos or IDENT software if the
complaint mentions one of those authentication types.
</para>
<para>
<ProgramListing>
FATAL 1: SetUserId: user 'joeblow' is not in 'pg_shadow'
</ProgramListing>
This is the fancy way of saying that the user doesn't exist at all.
</para>
<para>
<ProgramListing>
FATAL 1: Database testdb does not exist in pg_database
</ProgramListing>
The database you're trying to connect to doesn't exist. Note that
if you don't specify a database name, it defaults to the database
user name, which may or may not be the right thing.
</para>
</sect1>
</chapter>
doc/src/sgml/pg_options.sgml 已删除 100644 → 0
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<!--
$Header: /cvsroot/pgsql/doc/src/sgml/Attic/pg_options.sgml,v 1.5 2000/03/31 03:27:41 thomas Exp $
-->
<Chapter Id="pg-options-dev">
<DocInfo>
<AuthorGroup>
<Author>
<FirstName>Massimo</FirstName>
<Surname>Dal Zotto</Surname>
</Author>
</AuthorGroup>
<Date>Transcribed 1998-10-16</Date>
</DocInfo>
<Title>pg_options</Title>
<Para>
<Note>
<Para>
Contributed by <ULink url="mailto:dz@cs.unitn.it">Massimo Dal Zotto</ULink>
</Para>
</Note>
</para>
<Para>
The optional file <filename>data/pg_options</filename> contains runtime
options used by the backend to control trace messages and other backend
tunable parameters.
What makes this file interesting is the fact that it is re-read by a backend
when it receives a SIGHUP signal, making thus possible to change run-time
options on the fly without needing to restart
<productname>Postgres</productname>.
The options specified in this file may be debugging flags used by the trace
package (<filename>backend/utils/misc/trace.c</filename>) or numeric
parameters which can be used by the backend to control its behaviour.
New options and parameters must be defined in
<filename>backend/utils/misc/trace.c</filename> and
<filename>backend/include/utils/trace.h</filename>.
</para>
<Para>
For example suppose we want to add conditional trace messages and a tunable
numeric parameter to the code in file <filename>foo.c</filename>.
All we need to do is to add the constant TRACE_FOO and OPT_FOO_PARAM into
<filename>backend/include/utils/trace.h</filename>:
<programlisting>
/* file trace.h */
enum pg_option_enum {
...
TRACE_FOO, /* trace foo functions */
OPT_FOO_PARAM, /* foo tunable parameter */
NUM_PG_OPTIONS /* must be the last item of enum */
};
</programlisting>
and a corresponding line in <filename>backend/utils/misc/trace.c</filename>:
<programlisting>
/* file trace.c */
static char *opt_names[] = {
...
"foo", /* trace foo functions */
"fooparam" /* foo tunable parameter */
};
</programlisting>
Options in the two files must be specified in exactly the same order.
In the foo source files we can now reference the new flags with:
<programlisting>
/* file foo.c */
#include "trace.h"
#define foo_param pg_options[OPT_FOO_PARAM]
int
foo_function(int x, int y)
{
TPRINTF(TRACE_FOO, "entering foo_function, foo_param=%d", foo_param);
if (foo_param > 10) {
do_more_foo(x, y);
}
}
</programlisting>
</para>
<para>
Existing files using private trace flags can be changed by simply adding
the following code:
<programlisting>
#include "trace.h"
/* int my_own_flag = 0; -- removed */
#define my_own_flag pg_options[OPT_MY_OWN_FLAG]
</programlisting>
</para>
<para>
All pg_options are initialized to zero at backend startup. If we need a
different default value we must add some initialization code at the beginning
of <function>PostgresMain</function>.
Now we can set the foo_param and enable foo trace by writing values into the
<filename>data/pg_options</filename> file:
<programlisting>
# file pg_options
...
foo=1
fooparam=17
</programlisting>
</para>
<para>
The new options will be read by all new backends when they are started.
To make effective the changes for all running backends we need to send a
SIGHUP to the postmaster. The signal will be automatically sent to all the
backends. We can also activate the changes only for a specific backend by
sending the SIGHUP directly to it.
</para>
<para>
pg_options can also be specified with the <option>-T</option> switch of
<productname>Postgres</productname>:
<programlisting>
postgres <replaceable>options</replaceable> -T "verbose=2,query,hostlookup-"
</programlisting>
</para>
<Para>
The functions used for printing errors and debug messages can now make use
of the <citetitle>syslog(2)</citetitle> facility. Message printed to stdout
or stderr are prefixed by a timestamp containing also the backend pid:
<programlisting>
#timestamp #pid #message
980127.17:52:14.173 [29271] StartTransactionCommand
980127.17:52:14.174 [29271] ProcessUtility: drop table t;
980127.17:52:14.186 [29271] SIIncNumEntries: table is 70% full
980127.17:52:14.186 [29286] Async_NotifyHandler
980127.17:52:14.186 [29286] Waking up sleeping backend process
980127.19:52:14.292 [29286] Async_NotifyFrontEnd
980127.19:52:14.413 [29286] Async_NotifyFrontEnd done
980127.19:52:14.466 [29286] Async_NotifyHandler done
</programlisting>
</para>
<para>
This format improves readability of the logs and allows people to understand
exactly which backend is doing what and at which time. It also makes
easier to write simple awk or perl scripts which monitor the log to
detect database errors or problem, or to compute transaction time statistics.
</para>
<para>
Messages printed to syslog use the log facility LOG_LOCAL0.
The use of syslog can be controlled with the syslog pg_option.
Unfortunately many functions call directly <function>printf()</function>
to print their messages to stdout or stderr and this output can't be
redirected to syslog or have timestamps in it.
It would be advisable that all calls to printf would be replaced with the
PRINTF macro and output to stderr be changed to use EPRINTF instead so that
we can control all output in a uniform way.
</Para>
<Para>
The new pg_options mechanism is more convenient than defining new backend
option switches because:
<ItemizedList Mark="bullet" Spacing="compact">
<ListItem>
<Para>
we don't have to define a different switch for each thing we want to control.
All options are defined as keywords in an external file stored in the data
directory.
</Para>
</ListItem>
<ListItem>
<Para>
we don't have to restart <productname>Postgres</productname> to change
the setting of some option.
Normally backend options are specified to the postmaster and passed to each
backend when it is started. Now they are read from a file.
</Para>
</ListItem>
<ListItem>
<Para>
we can change options on the fly while a backend is running. We can thus
investigate some problem by activating debug messages only when the problem
appears. We can also try different values for tunable parameters.
</Para>
</ListItem>
</ItemizedList>
The format of the <filename>pg_options</filename> file is as follows:
<programlisting>
# <replaceable>comment</replaceable>
<replaceable>option</replaceable>=<replaceable class="parameter">integer_value</replaceable> # set value for <replaceable>option</replaceable>
<replaceable>option</replaceable> # set <replaceable>option</replaceable> = 1
<replaceable>option</replaceable>+ # set <replaceable>option</replaceable> = 1
<replaceable>option</replaceable>- # set <replaceable>option</replaceable> = 0
</programlisting>
Note that <replaceable class="parameter">keyword</replaceable> can also be
an abbreviation of the option name defined in
<filename>backend/utils/misc/trace.c</filename>.
</Para>
<para>
Refer to <citetitle>The Administrator's Guide</citetitle> chapter
on runtime options for a complete list of currently supported
options.
</para>
<Para>
Some of the existing code using private variables and option switches has
been changed to make use of the pg_options feature, mainly in
<filename>postgres.c</filename>. It would be advisable to modify
all existing code
in this way, so that we can get rid of many of the switches on
the <productname>Postgres</productname> command line
and can have more tunable options
with a unique place to put option values.
</Para>
</Chapter>
<!-- Keep this comment at the end of the file
Local variables:
mode:sgml
sgml-omittag:nil
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
sgml-parent-document:nil
sgml-default-dtd-file:"./reference.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:("/usr/lib/sgml/catalog")
sgml-local-ecat-files:nil
End:
-->
doc/src/sgml/postgres.sgml
浏览文件 @ 2c0edb3c
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/postgres.sgml,v 1.36 2000/05/02 20:01:52 thomas Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/postgres.sgml,v 1.37 2000/06/18 21:24:51 petere Exp $
-->
<!doctype book PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [
......@@ -58,9 +58,9 @@ $Header: /cvsroot/pgsql/doc/src/sgml/postgres.sgml,v 1.36 2000/05/02 20:01:52 th
<!entity regress SYSTEM "regress.sgml">
<!entity release SYSTEM "release.sgml">
<!entity runtime SYSTEM "runtime.sgml">
<!entity security SYSTEM "security.sgml">
<!entity client-auth SYSTEM "client-auth.sgml">
<!entity user-manag SYSTEM "user-manag.sgml">
<!entity start-ag SYSTEM "start-ag.sgml">
<!entity trouble SYSTEM "trouble.sgml">
<!-- programmer's guide -->
<!entity arch-pg SYSTEM "arch-pg.sgml">
......@@ -100,10 +100,8 @@ $Header: /cvsroot/pgsql/doc/src/sgml/postgres.sgml,v 1.36 2000/05/02 20:01:52 th
<!entity docguide SYSTEM "docguide.sgml">
<!entity geqo SYSTEM "geqo.sgml">
<!entity index SYSTEM "index.sgml">
<!entity options SYSTEM "pg_options.sgml">
<!entity page SYSTEM "page.sgml">
<!entity protocol SYSTEM "protocol.sgml">
<!entity signals SYSTEM "signals.sgml">
<!entity sources SYSTEM "sources.sgml">
]>
<!-- entity manpages SYSTEM "man/manpages.sgml" subdoc -->
......@@ -225,10 +223,10 @@ Your name here...
&install;
&installw;
&runtime;
&security;
&client-auth;
&user-manag;
&start-ag;
&manage-ag;
&trouble;
&recovery;
&regress;
&release;
......@@ -292,7 +290,6 @@ Your name here...
</partintro>
&sources;
&arch-dev;
&options;
&geqo;
<!--
This listing of Postgres catalogs is currently just a copy of the old
......@@ -301,7 +298,6 @@ Your name here...
&catalogs;
-->
&protocol;
&signals;
&compiler;
&bki;
&page;
......
doc/src/sgml/programmer.sgml
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<!--
$Header: /cvsroot/pgsql/doc/src/sgml/Attic/programmer.sgml,v 1.26 2000/05/02 20:01:52 thomas Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/Attic/programmer.sgml,v 1.27 2000/06/18 21:24:51 petere Exp $
Postgres Programmer's Guide.
-->
......@@ -50,10 +50,8 @@ Postgres Programmer's Guide.
<!entity cvs SYSTEM "cvs.sgml">
<!entity docguide SYSTEM "docguide.sgml">
<!entity geqo SYSTEM "geqo.sgml">
<!entity options SYSTEM "pg_options.sgml">
<!entity page SYSTEM "page.sgml">
<!entity protocol SYSTEM "protocol.sgml">
<!entity signals SYSTEM "signals.sgml">
<!entity sources SYSTEM "sources.sgml">
]>
......@@ -165,7 +163,6 @@ Disable it until we put in some info.
&sources;
&arch-dev;
&options;
&geqo;
<!--
This listing of Postgres catalogs is currently just a copy of the old
......@@ -174,7 +171,6 @@ Disable it until we put in some info.
&catalogs;
-->
&protocol;
&signals;
&compiler;
&bki;
&page;
......
doc/src/sgml/ref/allfiles.sgml
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<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/allfiles.sgml,v 1.18 2000/04/14 15:17:28 thomas Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/allfiles.sgml,v 1.19 2000/06/18 21:24:51 petere Exp $
Postgres documentation
Complete list of usable sgml source files in this directory.
-->
......@@ -98,6 +98,8 @@ Complete list of usable sgml source files in this directory.
<!entity select system "select.sgml">
<!entity selectInto system "select_into.sgml">
<!entity set system "set.sgml">
<!entity setConstraints system "set_constraints.sgml">
<!entity setTransaction system "set_transaction.sgml">
<!entity show system "show.sgml">
<!entity truncate system "truncate.sgml">
<!entity unlisten system "unlisten.sgml">
......
doc/src/sgml/ref/commands.sgml
浏览文件 @ 2c0edb3c
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/Attic/commands.sgml,v 1.25 2000/04/14 15:17:28 thomas Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/Attic/commands.sgml,v 1.26 2000/06/18 21:24:51 petere Exp $
Postgres documentation
-->
......@@ -72,6 +72,8 @@ Postgres documentation
&select;
&selectInto;
&set;
&setConstraints;
&setTransaction;
&show;
&truncate;
&unlisten;
......
doc/src/sgml/ref/reset.sgml
浏览文件 @ 2c0edb3c
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/reset.sgml,v 1.8 2000/04/08 02:39:02 tgl Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/reset.sgml,v 1.9 2000/06/18 21:24:51 petere Exp $
Postgres documentation
-->
<refentry id="SQL-RESET">
<refmeta>
<refentrytitle id="SQL-RESET-TITLE">
RESET
</refentrytitle>
<refentrytitle id="SQL-RESET-TITLE">RESET</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>
RESET
</refname>
<refpurpose>
Restores run-time parameters for session to default values
</refpurpose>
<refname>RESET</refname>
<refpurpose>Restores run-time parameters to default values</refpurpose>
</refnamediv>
<refsynopsisdiv>
<refsynopsisdivinfo>
<date>1999-07-20</date>
</refsynopsisdivinfo>
<synopsis>
RESET <replaceable class="PARAMETER">variable</replaceable>
</synopsis>
<refsect2 id="R2-SQL-RESET-1">
<refsect2info>
<date>1998-09-24</date>
</refsect2info>
<title>
Inputs
</title>
<title>Inputs</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable class="PARAMETER">variable</replaceable></term>
<listitem>
<para>
Refer to
<xref linkend="sql-set-title" endterm="sql-set-title">
for more information on available variables.
The name of a run-time parameter. See <xref
linkend="sql-set-title" endterm="sql-set-title"> for a list.
</para>
</listitem>
</varlistentry>
......@@ -49,107 +34,55 @@ RESET <replaceable class="PARAMETER">variable</replaceable>
</para>
</refsect2>
<refsect2 id="R2-SQL-RESET-2">
<refsect2info>
<date>1998-09-24</date>
</refsect2info>
<title>
Outputs
</title>
<para>
<variablelist>
<varlistentry>
<term><computeroutput>
RESET VARIABLE
</computeroutput></term>
<listitem>
<para>
Message returned if
<replaceable class="PARAMETER">variable</replaceable> is successfully reset
to its default value.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect2>
</refsynopsisdiv>
<refsect1 id="R1-SQL-RESET-1">
<refsect1info>
<date>1998-09-24</date>
</refsect1info>
<title>
Description
</title>
<refsect1>
<title>Description</title>
<para>
<command>RESET</command> restores variables to their
default values.
Refer to
<command>RESET</command> restores run-time parameters to their
default values. Refer to
<xref linkend="sql-set-title" endterm="sql-set-title">
for details on allowed values and defaults.
<command>RESET</command> is an alternate form for
for details. <command>RESET</command> is an alternate form for
<synopsis>
SET <replaceable class="parameter">variable</replaceable> = DEFAULT
SET <replaceable class="parameter">variable</replaceable> TO DEFAULT
</synopsis>
</para>
</refsect1>
<refsect2 id="R2-SQL-RESET-3">
<refsect2info>
<date>1998-09-24</date>
</refsect2info>
<title>
Notes
</title>
<para>
See also
<xref linkend="sql-set-title" endterm="sql-set-title"> and
<xref linkend="sql-show-title" endterm="sql-show-title">
to manipulate variable values.
</para>
</refsect2>
<refsect1>
<title>Diagnostics</title>
<para>
See under the <xref linkend="sql-set-title"
endterm="sql-set-title"> command.
</para>
</refsect1>
<refsect1 id="R1-SQL-RESET-2">
<title>
Usage
</title>
<refsect1>
<title>Examples</title>
<para>
Set DateStyle to its default value:
<programlisting>
<screen>
RESET DateStyle;
</programlisting>
</screen>
</para>
<para>
Set Geqo to its default value:
<programlisting>
<screen>
RESET GEQO;
</programlisting>
</screen>
</para>
</refsect1>
<refsect1 id="R1-SQL-RESET-3">
<title>
Compatibility
</title>
<refsect1>
<title>Compatibility</title>
<refsect2 id="R2-SQL-RESET-4">
<refsect2info>
<date>1998-09-24</date>
</refsect2info>
<title>
SQL92
</title>
<para>
There is no <command>RESET</command> in <acronym>SQL92</acronym>.
</para>
</refsect2>
<para>
<command>RESET</command> is a <productname>Postgres</productname> extension.
</para>
</refsect1>
</refentry>
......
doc/src/sgml/ref/set.sgml
浏览文件 @ 2c0edb3c
此差异已折叠。
doc/src/sgml/ref/set_constraints.sgml 0 → 100644
浏览文件 @ 2c0edb3c
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/set_constraints.sgml,v 1.1 2000/06/18 21:24:54 petere Exp $ -->
<refentry id="SQL-SET-CONSTRAINTS">
<refmeta>
<refentrytitle id="SQL-SET-CONSTRAINTS-title">SET CONSTRAINTS</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>SET CONSTRAINTS</refname>
<refpurpose>Set the constraint mode of the current SQL-transaction</refpurpose>
</refnamediv>
<refsynopsisdiv>
<refsynopsisdivinfo>
<date>2000-06-01</date>
</refsynopsisdivinfo>
<synopsis>
SET CONSTRAINTS { ALL | <replaceable class="parameter">constraint</replaceable> [, ...] } { DEFERRED | IMMEDIATE }
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>SET CONSTRAINTS</command> sets the behavior of constraint
evaluation in the current transaction. In
<option>IMMEDIATE</option> mode, constraints are checked at the end
of each statement. In <option>DEFERRED</option> mode, constraints
are not checked until transaction commit.
</para>
<para>
Upon creation, a constraint is always give one of three
characteristics: <option>INITIALLY DEFERRED</option>,
<option>INITIALLY IMMEDIATE DEFERRABLE</option>, or
<option>INITIALLY IMMEDIATE NOT DEFERRABLE</option>. The third
class is not affected by the <command>SET CONSTRAINTS</command>
command.
</para>
<para>
Currently, only foreign key constraints are affected by this
setting. Check and unique constraints are always effectively
initially immediate not deferrable.
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
SQL92, SQL99
</para>
</refsect1>
</refentry>
doc/src/sgml/ref/set_transaction.sgml 0 → 100644
浏览文件 @ 2c0edb3c
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/set_transaction.sgml,v 1.1 2000/06/18 21:24:54 petere Exp $ -->
<refentry id="SQL-SET-TRANSACTION">
<refmeta>
<refentrytitle id="SQL-SET-TRANSACTION-title">SET TRANSACTION</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>SET TRANSACTION</refname>
<refpurpose>Set the characteristics of the current SQL-transaction</refpurpose>
</refnamediv>
<refsynopsisdiv>
<refsynopsisdivinfo>
<date>2000-06-01</date>
</refsynopsisdivinfo>
<synopsis>
SET TRANSACTION ISOLATION LEVEL { READ COMMITTED | SERIALIZABLE }
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
The <command>SET TRANSACTION</command> command sets the
characteristics for the current SQL-transaction. It has no effect
on any subsequent transactions. This command cannot be used after
the first DML statement (<command>SELECT</command>,
<command>INSERT</command>, <command>DELETE</command>,
<command>UPDATE</command>, <command>FETCH</command>,
<command>COPY</command>) of a transaction has been executed.
</para>
<para>
The isolation level of a transaction determines what data the
transaction can see when other transactions are running concurrently.
<variablelist>
<varlistentry>
<term>READ COMMITTED</term>
<listitem>
<para>
A statement can only see rows committed before it began. This
is the default.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>SERIALIZABLE</term>
<listitem>
<para>
The current transaction can only see rows committed before
first DML statement was executed in this transaction.
</para>
<tip>
<para>
Intuitively, serializable means that two concurrent
transactions will leave the database in the same state as if
the two has been executed strictly after one another in either
order.
</para>
</tip>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
SQL92, SQL99
</para>
<para>
SERIALIZABLE is the default level in <acronym>SQL</acronym>.
Postgres does not provide the isolation levels <option>READ
UNCOMMITTED</option> and <option>REPEATABLE READ</option>. Because
of multi-version concurrency control, the serializable level is not
truly serializable. See the <citetitle>User's Guide</citetitle> for
details.
</para>
<para>
In <acronym>SQL</acronym> there are two other transaction
characteristics that can be set with this command: whether the
transaction is read-only and the size of the diagnostics area.
Neither of these concepts are supported in Postgres.
</para>
</refsect1>
</refentry>
doc/src/sgml/ref/show.sgml
浏览文件 @ 2c0edb3c
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/show.sgml,v 1.9 2000/04/08 02:39:02 tgl Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/show.sgml,v 1.10 2000/06/18 21:24:54 petere Exp $
Postgres documentation
-->
<refentry id="SQL-SHOW">
<refmeta>
<refentrytitle id="SQL-SHOW-TITLE">
SHOW
</refentrytitle>
<refentrytitle id="SQL-SHOW-TITLE">SHOW</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>
SHOW
</refname>
<refpurpose>
Shows run-time parameters for session
</refpurpose>
<refname>SHOW</refname>
<refpurpose>Shows run-time parameters</refpurpose>
</refnamediv>
<refsynopsisdiv>
<refsynopsisdivinfo>
<date>1999-07-20</date>
</refsynopsisdivinfo>
<synopsis>
SHOW <replaceable class="PARAMETER">keyword</replaceable>
SHOW <replaceable class="PARAMETER">name</replaceable>
</synopsis>
<refsect2 id="R2-SQL-SHOW-1">
<refsect2info>
<date>1998-09-24</date>
</refsect2info>
<title>
Inputs
</title>
<title>Inputs</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable class="PARAMETER">keyword</replaceable></term>
<term><replaceable class="PARAMETER">name</replaceable></term>
<listitem>
<para>
Refer to
The name of a run-time parameter. See
<xref linkend="sql-set-title" endterm="sql-set-title">
for more information on available variables.
for a list.
</para>
</listitem>
</varlistentry>
......@@ -50,41 +36,43 @@ SHOW <replaceable class="PARAMETER">keyword</replaceable>
</para>
</refsect2>
<refsect2 id="R2-SQL-SHOW-2">
<refsect2info>
<date>1998-09-24</date>
</refsect2info>
<title>
Outputs
</title>
</refsynopsisdiv>
<refsect1 id="R1-SQL-SHOW-1">
<title>Description</title>
<para>
<command>SHOW</command> will display the current setting of a
run-time parameter. These variables can be set using the
<command>SET</command> statement or are determined at server start.
</para>
</refsect1>
<refsect1>
<title>Diagnostics</title>
<para>
<variablelist>
<varlistentry>
<term><computeroutput>
NOTICE: <replaceable class="PARAMETER">variable</replaceable> is <replaceable>value</replaceable>
</computeroutput></term>
<term><computeroutput>ERROR: not a valid option name: <replaceable>name</replaceable></computeroutput></term>
<listitem>
<para>
Message returned if successful.
Message returned if <replaceable>variable</replaceable> does
not stand for an existing parameter.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><computeroutput>
NOTICE: Unrecognized variable <replaceable>value</replaceable>
</computeroutput></term>
<term><computeroutput>ERROR: permission denied</computeroutput></term>
<listitem>
<para>
Message returned if <returnvalue>variable</returnvalue> does not exist.
You must be a superuser to be allowed to see certain settings.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><computeroutput>
NOTICE: Time zone is unknown
</computeroutput></term>
<term><computeroutput>NOTICE: Time zone is unknown</computeroutput></term>
<listitem>
<para>
If the <envar>TZ</envar> or <envar>PGTZ</envar> environment
......@@ -94,82 +82,35 @@ NOTICE: Time zone is unknown
</varlistentry>
</variablelist>
</para>
</refsect2>
</refsynopsisdiv>
<refsect1 id="R1-SQL-SHOW-1">
<refsect1info>
<date>1998-09-24</date>
</refsect1info>
<title>
Description
</title>
<para>
<command>SHOW</command> will display the current setting of a
run-time parameter during a session.
</para>
<para>
These variables can be set using the <command>SET</command> statement,
and
can be restored to the default values using the <command>RESET</command>
statement.
Parameters and values are case-insensitive.
</para>
<refsect2 id="R2-SQL-SHOW-3">
<refsect2info>
<date>1998-09-24</date>
</refsect2info>
<title>
Notes
</title>
<para>
See also
<xref linkend="sql-set-title" endterm="sql-set-title"> and
<xref linkend="sql-reset-title" endterm="sql-reset-title">
to manipulate variable values.
</para>
</refsect2>
</refsect1>
<refsect1 id="R1-SQL-SHOW-2">
<title>
Usage
</title>
<title>Examples</title>
<para>
Show the current <literal>DateStyle</literal> setting:
<programlisting>
<screen>
SHOW DateStyle;
NOTICE: DateStyle is ISO with US (NonEuropean) conventions
</programlisting>
</screen>
</para>
<para>
Show the current genetic optimizer (<literal>geqo</literal>) setting:
<programlisting>
<screen>
SHOW GEQO;
NOTICE: GEQO is ON beginning with 11 relations
</programlisting>
NOTICE: geqo = true
</screen>
</para>
</refsect1>
<refsect1 id="R1-SQL-SHOW-3">
<title>
Compatibility
</title>
<title>Compatibility</title>
<refsect2 id="R2-SQL-SHOW-4">
<refsect2info>
<date>1998-09-24</date>
</refsect2info>
<title>
SQL92
</title>
<para>
There is no <command>SHOW</command> defined in <acronym>SQL92</acronym>.
</para>
</refsect2>
<para>
The <command>SHOW</command> command is a
<productname>Postgres</productname> extension.
</para>
</refsect1>
</refentry>
......
doc/src/sgml/runtime.sgml
浏览文件 @ 2c0edb3c
此差异已折叠。
doc/src/sgml/security.sgml 已删除 100644 → 0
浏览文件 @ b4e906f1
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/Attic/security.sgml,v 1.9 2000/05/25 15:32:03 momjian Exp $
-->
<chapter id="security">
<Title>Security</Title>
<Para>
Database security is addressed at several levels:
<itemizedlist>
<listitem>
<para>
Data base file protection. All files stored within the database
are protected from reading by any account other than the
<productname>Postgres</productname> superuser account.
</para>
</listitem>
<listitem>
<para>
Connections from a client to the database server are, by
default, allowed only via a local Unix socket, not via TCP/IP
sockets. The backend must be started with the
<literal>-i</literal> option to allow non-local clients to connect.
</para>
</listitem>
<listitem>
<para>
Client connections can be restricted by IP address and/or user
name via the <filename>pg_hba.conf</filename> file in <envar>PG_DATA</envar>.
</para>
</listitem>
<listitem>
<para>
Client connections may be authenticated via other external packages.
</para>
</listitem>
<listitem>
<para>
Each user in <productname>Postgres</productname> is assigned a
username and (optionally) a password. By default, users do not
have write access to databases they did not create.
</para>
</listitem>
<listitem>
<para>
Users may be assigned to <firstterm>groups</firstterm>, and
table access may be restricted based on group privileges.
</para>
</listitem>
</itemizedlist>
</para>
<Sect1>
<Title>User Authentication</Title>
<Para>
<firstterm>Authentication</firstterm>
is the process by which the backend server and
<application>postmaster</application>
ensure that the user requesting access to data is in fact who he/she
claims to be.
All users who invoke <Productname>Postgres</Productname> are checked against the
contents of the <literal>pg_user</literal> class to ensure that they are
authorized to do so. However, verification of the user's actual
identity is performed in a variety of ways:
<variablelist>
<varlistentry>
<term>
From the user shell
</term>
<listitem>
<para>
A backend server started from a user shell notes the user's (effective)
user-id before performing a
<function>setuid</function>
to the user-id of user <replaceable>postgres</replaceable>.
The effective user-id is used
as the basis for access control checks. No other authentication is
conducted.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
From the network
</term>
<listitem>
<para>
If the <Productname>Postgres</Productname> system is built as distributed,
access to the Internet TCP port of the
<application>postmaster</application>
process is available to anyone. The DBA configures the pg_hba.conf file
in the PGDATA directory to specify what authentication system is to be used
according to the host making the connection and which database it is
connecting to. See <citetitle>pg_hba.conf(5)</citetitle>
for a description of the authentication
systems available. Of course, host-based authentication is not fool-proof in
Unix, either. It is possible for determined intruders to also
masquerade the origination host. Those security issues are beyond the
scope of <Productname>Postgres</Productname>.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<Sect2>
<Title>Host-Based Access Control</Title>
<Para>
<firstterm>Host-based access control</firstterm>
is the name for the basic controls PostgreSQL
exercises on what clients are allowed to access a database and how
the users on those clients must authenticate themselves.
</para>
<para>
Each database system contains a file named
<filename>pg_hba.conf</filename>, in its <envar>PGDATA</envar>
directory, which controls who can connect to each database.
</para>
<para>
Every client accessing a database
<emphasis>must</emphasis>
be covered by one of
the entries in <filename>pg_hba.conf</filename>.
Otherwise all attempted connections from that
client will be rejected with a "User authentication failed" error
message.
</para>
<para>
The general format of the <filename>pg_hba.conf</filename>
file is of a set of records, one per
line. Blank lines and lines beginning with a hash character
("#") are ignored. A record is
made up of a number of fields which are separated by spaces and/or tabs.
</para>
<para>
Connections from clients can be made using Unix domain sockets or Internet
domain sockets (ie. TCP/IP). Connections made using Unix domain sockets
are controlled using records of the following format:
<synopsis>
local <replaceable>database</replaceable> <replaceable>authentication method</replaceable>
</synopsis>
where
<simplelist>
<member>
<replaceable>database</replaceable>
specifies the database that this record applies to. The value
<literal>all</literal>
specifies that it applies to all databases.
</member>
<member>
<replaceable>authentication method</replaceable>
specifies the method a user must use to authenticate themselves when
connecting to that database using Unix domain sockets. The different methods
are described below.
</member>
</simplelist>
</para>
<para>
Connections made using Internet domain sockets are controlled using records
of the following format.
<synopsis>
host <replaceable>database</replaceable> <replaceable>TCP/IP address</replaceable> <replaceable>TCP/IP mask</replaceable> <replaceable>authentication method</replaceable>
</synopsis>
</para>
<para>
The <replaceable>TCP/IP address</replaceable>
is logically anded to both the specified
<replaceable>TCP/IP mask</replaceable>
and the TCP/IP address
of the connecting client.
If the two resulting values are equal then the
record is used for this connection. If a connection matches more than one
record then the earliest one in the file is used.
Both the
<replaceable>TCP/IP address</replaceable>
and the
<replaceable>TCP/IP mask</replaceable>
are specified in dotted decimal notation.
</para>
<para>
If a connection fails to match any record then the
<firstterm>reject</firstterm>
authentication method is applied (see below).
</para>
<sect3>
<title>Authentication Methods</title>
<para>
The following authentication methods are supported for both Unix and TCP/IP
domain sockets:
<variablelist>
<varlistentry>
<term>trust</term>
<listitem>
<para>
The connection is allowed unconditionally.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>reject</term>
<listitem>
<para>
The connection is rejected unconditionally.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>crypt</term>
<listitem>
<para>
The client is asked for a password for the user. This is sent encrypted
(using <citetitle>crypt(3)</citetitle>)
and compared against the password held in the
<filename>pg_shadow</filename> table.
If the passwords match, the connection is allowed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>password</term>
<listitem>
<para>
The client is asked for a password for the user. This is sent in clear
and compared against the password held in the
<filename>pg_shadow</filename> table.
If the passwords match, the connection is allowed. An optional password file
may be specified after the
<literal>password</literal>
keyword which is used to match the supplied password rather than the pg_shadow
table. See
<citerefentry><refentrytitle>pg_passwd</refentrytitle></citerefentry>.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<para>
The following authentication methods are supported for TCP/IP
domain sockets only:
<variablelist>
<varlistentry>
<term>krb4</term>
<listitem>
<para>
Kerberos V4 is used to authenticate the user.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>krb5</term>
<listitem>
<para>
Kerberos V5 is used to authenticate the user.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>ident</term>
<listitem>
<para>
The ident server on the client is used to authenticate the user (RFC 1413).
An optional map name may be specified after the
<literal>ident</literal>
keyword which allows ident user names to be mapped onto
<productname>Postgres</productname> user names.
Maps are held in the file
<filename>$<envar>PGDATA</envar>/pg_ident.conf</filename>.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</sect3>
<sect3>
<title>Examples</title>
<para>
<programlisting>
# Trust any connection via Unix domain sockets.
local trust
# Trust any connection via TCP/IP from this machine.
host all 127.0.0.1 255.255.255.255 trust
# We don't like this machine.
host all 192.168.0.10 255.255.255.0 reject
# This machine can't encrypt so we ask for passwords in clear.
host all 192.168.0.3 255.255.255.0 password
# The rest of this group of machines should provide encrypted passwords.
host all 192.168.0.0 255.255.255.0 crypt
</programlisting>
</para>
</sect3>
</sect2>
</sect1>
<sect1>
<title>User Names and Groups</title>
<para>
To define a new user, run the
<application>createuser</application> utility program.
</para>
<para>
To assign a user or set of users to a new group, one must
define the group itself, and assign users to that group. In
<application>Postgres</application> these steps are not currently
supported with a <command>create group</command> command. Instead,
the groups are defined by inserting appropriate values into the
<literal>pg_group</literal> system table, and then using the
<command>grant</command> command to assign privileges to the
group.
</para>
<sect2>
<title>Creating Users</title>
<para>
</para>
</sect2>
<sect2>
<title>Creating Groups</title>
<para>
Currently, there is no easy interface to set up user groups. You
have to explicitly insert/update the <literal>pg_group table</literal>.
For example:
<programlisting>
jolly=> insert into pg_group (groname, grosysid, grolist)
jolly=> values ('posthackers', '1234', '{5443, 8261}');
INSERT 548224
jolly=> grant insert on foo to group posthackers;
CHANGE
jolly=>
</programlisting>
</para>
<para>
The fields in <filename>pg_group</filename> are:
<variablelist>
<varlistentry>
<term>groname</term>
<listitem>
<para>
The group name. This a name and should be purely
alphanumeric. Do not include underscores or other punctuation.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>grosysid</term>
<listitem>
<para>
The group id. This is an int4. This should be unique for
each group.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>grolist</term>
<listitem>
<para>
The list of pg_user id's that belong in the group. This
is an int4[].
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</sect2>
<sect2>
<title>Assigning Users to Groups</title>
<para>
</para>
</sect2>
</sect1>
<Sect1>
<Title>Access Control</Title>
<Para>
<Productname>Postgres</Productname> provides mechanisms to allow users
to limit the access to their data that is provided to other users.
<variablelist>
<varlistentry>
<term>
Database superusers
</term>
<listitem>
<para>
Database super-users (i.e., users who have <literal>pg_user.usesuper</literal>
set) silently bypass all of the access controls described below with
two exceptions: manual system catalog updates are not permitted if the
user does not have <literal>pg_user.usecatupd</literal> set, and destruction of
system catalogs (or modification of their schemas) is never allowed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
Access Privilege
</term>
<listitem>
<para>
The use of access privilege to limit reading, writing and setting
of rules on classes is covered in
<citetitle>grant/revoke(l)</citetitle>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
Class removal and schema modification
</term>
<listitem>
<para>
Commands that destroy or modify the structure of an existing class,
such as <command>alter</command>,
<command>drop table</command>,
and
<command>drop index</command>,
only operate for the owner of the class. As mentioned above, these
operations are <emphasis>never</emphasis>
permitted on system catalogs.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</sect1>
<Sect1>
<Title>Functions and Rules</Title>
<Para>
Functions and rules allow users to insert code into the backend server
that other users may execute without knowing it. Hence, both
mechanisms permit users to <firstterm>trojan horse</firstterm>
others with relative impunity. The only real protection is tight
control over who can define functions (e.g., write to relations with
SQL fields) and rules. Audit trails and alerters on
<literal>pg_class</literal>, <literal>pg_user</literal>
and <literal>pg_group</literal> are also recommended.
</para>
<Sect2>
<Title>Functions</Title>
<Para>
Functions written in any language except SQL
run inside the backend server
process with the permissions of the user <replaceable>postgres</replaceable> (the
backend server runs with its real and effective user-id set to
<replaceable>postgres</replaceable>. It is possible for users to change the server's
internal data structures from inside of trusted functions. Hence,
among many other things, such functions can circumvent any system
access controls. This is an inherent problem with user-defined C functions.
</para>
</sect2>
<Sect2>
<Title>Rules</Title>
<Para>
Like SQL functions, rules always run with the identity and
permissions of the user who invoked the backend server.
</para>
</sect2>
<sect2>
<title>Caveats</title>
<para>
There are no plans to explicitly support encrypted data inside of
<Productname>Postgres</Productname>
(though there is nothing to prevent users from encrypting
data within user-defined functions). There are no plans to explicitly
support encrypted network connections, either, pending a total rewrite
of the frontend/backend protocol.
</para>
<para>
User names, group names and associated system identifiers (e.g., the
contents of <literal>pg_user.usesysid</literal>) are assumed to be unique
throughout a database. Unpredictable results may occur if they are
not.
</para>
</sect2>
</sect1>
<sect1>
<title>Secure TCP/IP Connection</title>
<para>
<note>
<title>Author</title>
<para>
From e-mail by
<ulink url="selkovjr@mcs.anl.gov">Gene Selkov, Jr.</ulink>
written on 1999-09-08 in response to a
question from Eric Marsden.
</para>
</note>
</para>
<para>
One can use <productname>ssh</productname> to encrypt the network
connection between clients and a
<productname>Postgres</productname> server. Done properly, this
should lead to an adequately secure network connection.
</para>
<para>
The documentation for <productname>ssh</productname> provides most
of the information to get started.
Please refer to
<ulink url="http://www.heimhardt.de/htdocs/ssh.html">http://www.heimhardt.de/htdocs/ssh.html</ulink>
for better insight.
</para>
<para>
A step-by-step explanation can be done in just two steps.
</para>
<procedure>
<title>Running a secure tunnel via ssh</title>
<para>
A step-by-step explanation can be done in just two steps.
</para>
<step performance="required" id="establish-tunnel">
<para>
Establish a tunnel to the backend machine, like this:
<programlisting>
ssh -L 3333:wit.mcs.anl.gov:5432 postgres@wit.mcs.anl.gov
</programlisting>
The first number in the -L argument, 3333, is the port number of
your end of the tunnel. The second number, 5432, is the remote
end of the tunnel -- the port number your backend is using. The
name or the address in between the port numbers belongs to the
server machine, as does the last argument to ssh that also includes
the optional user name. Without the user name, ssh will try the
name you are currently logged on as on the client machine. You can
use any user name the server machine will accept, not necessarily
those related to postgres.
</para>
</step>
<step performance="required">
<para>
Now that you have a running ssh session, you can connect a
postgres client to your local host at the port number you
specified in the previous step. If it's
<application>psql</application>, you will need another shell
because the shell session you used in
<xref linkend="establish-tunnel"> is now occupied with
<application>ssh</application>.
<programlisting>
psql -h localhost -p 3333 -d mpw
</programlisting>
Note that you have to specify the <option>-h</option> argument
to cause your client to use the TCP socket instead of the Unix
socket. You can omit the port argument if you chose 5432 as your
end of the tunnel.
</para>
</step>
</procedure>
</sect1>
</chapter>
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<chapter id="newuser">
<title>Adding and Deleting Users</title>
<para>
<application>createuser</application> enables specific users to access
<productname>Postgres</productname>.
<application>dropuser</application> removes users and
prevents them from accessing <productname>Postgres</productname>.
</para>
<para>
These commands only affect users with respect to
<productname>Postgres</productname>;
they have no effect on a user's other privileges or status with regards
to the underlying operating system.
</para>
</chapter>
<chapter id="disk">
<title>Disk Management</title>
......
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