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><DIV
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><H1
CLASS="SECT1"
><A
NAME="RUNTIME-CONFIG-CONNECTION"
>18.3. Connections and Authentication</A
></H1
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="RUNTIME-CONFIG-CONNECTION-SETTINGS"
>18.3.1. Connection Settings</A
></H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><A
NAME="GUC-LISTEN-ADDRESSES"
></A
><TT
CLASS="VARNAME"
>listen_addresses</TT
> (<TT
CLASS="TYPE"
>string</TT
>)</DT
><DD
><P
> Specifies the TCP/IP address(es) on which the server is
to listen for connections from client applications.
The value takes the form of a comma-separated list of host names
and/or numeric IP addresses. The special entry <TT
CLASS="LITERAL"
>*</TT
>
corresponds to all available IP interfaces.
If the list is empty, the server does not listen on any IP interface
at all, in which case only Unix-domain sockets can be used to connect
to it.
The default value is <SPAN
CLASS="SYSTEMITEM"
>localhost</SPAN
>,
which allows only local <SPAN
CLASS="QUOTE"
>"loopback"</SPAN
> connections to be made.
This parameter can only be set at server start.
</P
></DD
><DT
><A
NAME="GUC-PORT"
></A
><TT
CLASS="VARNAME"
>port</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> The TCP port the server listens on; 5432 by default. Note that the
same port number is used for all IP addresses the server listens on.
This parameter can only be set at server start.
</P
></DD
><DT
><A
NAME="GUC-MAX-CONNECTIONS"
></A
><TT
CLASS="VARNAME"
>max_connections</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Determines the maximum number of concurrent connections to the
database server. The default is typically 100 connections, but
might be less if your kernel settings will not support it (as
determined during <SPAN
CLASS="APPLICATION"
>initdb</SPAN
>). This parameter can
only be set at server start.
</P
><P
> Increasing this parameter might cause <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>
to request more <SPAN
CLASS="SYSTEMITEM"
>System V</SPAN
> shared
memory or semaphores than your operating system's default configuration
allows. See <A
HREF="kernel-resources.html#SYSVIPC"
>Section 17.4.1</A
> for information on how to
adjust those parameters, if necessary.
</P
></DD
><DT
><A
NAME="GUC-SUPERUSER-RESERVED-CONNECTIONS"
></A
><TT
CLASS="VARNAME"
>superuser_reserved_connections</TT
>
(<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Determines the number of connection <SPAN
CLASS="QUOTE"
>"slots"</SPAN
> that
are reserved for connections by <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>
superusers. At most <A
HREF="runtime-config-connection.html#GUC-MAX-CONNECTIONS"
>max_connections</A
>
connections can ever be active simultaneously. Whenever the
number of active concurrent connections is at least
<TT
CLASS="VARNAME"
>max_connections</TT
> minus
<TT
CLASS="VARNAME"
>superuser_reserved_connections</TT
>, new
connections will be accepted only for superusers.
</P
><P
> The default value is three connections. The value must be less
than the value of <TT
CLASS="VARNAME"
>max_connections</TT
>. This
parameter can only be set at server start.
</P
></DD
><DT
><A
NAME="GUC-UNIX-SOCKET-DIRECTORY"
></A
><TT
CLASS="VARNAME"
>unix_socket_directory</TT
> (<TT
CLASS="TYPE"
>string</TT
>)</DT
><DD
><P
> Specifies the directory of the Unix-domain socket on which the
server is to listen for
connections from client applications. The default is normally
<TT
CLASS="FILENAME"
>/tmp</TT
>, but can be changed at build time.
This parameter can only be set at server start.
</P
></DD
><DT
><A
NAME="GUC-UNIX-SOCKET-GROUP"
></A
><TT
CLASS="VARNAME"
>unix_socket_group</TT
> (<TT
CLASS="TYPE"
>string</TT
>)</DT
><DD
><P
> Sets the owning group of the Unix-domain socket. (The owning
user of the socket is always the user that starts the
server.) In combination with the parameter
<TT
CLASS="VARNAME"
>unix_socket_permissions</TT
> this can be used as
an additional access control mechanism for Unix-domain connections.
By default this is the empty string, which selects the default
group for the current user. This parameter can only be set at
server start.
</P
></DD
><DT
><A
NAME="GUC-UNIX-SOCKET-PERMISSIONS"
></A
><TT
CLASS="VARNAME"
>unix_socket_permissions</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Sets the access permissions of the Unix-domain socket. Unix-domain
sockets use the usual Unix file system permission set.
The parameter value is expected to be a numeric mode
specification in the form accepted by the
<CODE
CLASS="FUNCTION"
>chmod</CODE
> and <CODE
CLASS="FUNCTION"
>umask</CODE
>
system calls. (To use the customary octal format the number
must start with a <TT
CLASS="LITERAL"
>0</TT
> (zero).)
</P
><P
> The default permissions are <TT
CLASS="LITERAL"
>0777</TT
>, meaning
anyone can connect. Reasonable alternatives are
<TT
CLASS="LITERAL"
>0770</TT
> (only user and group, see also
<TT
CLASS="VARNAME"
>unix_socket_group</TT
>) and <TT
CLASS="LITERAL"
>0700</TT
>
(only user). (Note that for a Unix-domain socket, only write
permission matters and so there is no point in setting or revoking
read or execute permissions.)
</P
><P
> This access control mechanism is independent of the one
described in <A
HREF="client-authentication.html"
>Chapter 19</A
>.
</P
><P
> This parameter can only be set at server start.
</P
></DD
><DT
><A
NAME="GUC-BONJOUR-NAME"
></A
><TT
CLASS="VARNAME"
>bonjour_name</TT
> (<TT
CLASS="TYPE"
>string</TT
>)</DT
><DD
><P
> Specifies the <SPAN
CLASS="PRODUCTNAME"
>Bonjour</SPAN
> broadcast
name. The computer name is used if this parameter is set to the
empty string <TT
CLASS="LITERAL"
>''</TT
> (which is the default). This parameter is
ignored if the server was not compiled with
<SPAN
CLASS="PRODUCTNAME"
>Bonjour</SPAN
> support.
This parameter can only be set at server start.
</P
></DD
><DT
><A
NAME="GUC-TCP-KEEPALIVES-IDLE"
></A
><TT
CLASS="VARNAME"
>tcp_keepalives_idle</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> On systems that support the <TT
CLASS="SYMBOL"
>TCP_KEEPIDLE</TT
> socket option, specifies the
number of seconds between sending keepalives on an otherwise idle
connection. A value of zero uses the system default. If <TT
CLASS="SYMBOL"
>TCP_KEEPIDLE</TT
> is
not supported, this parameter must be zero. This parameter is ignored for
connections made via a Unix-domain socket.
</P
></DD
><DT
><A
NAME="GUC-TCP-KEEPALIVES-INTERVAL"
></A
><TT
CLASS="VARNAME"
>tcp_keepalives_interval</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> On systems that support the <TT
CLASS="SYMBOL"
>TCP_KEEPINTVL</TT
> socket option, specifies how
long, in seconds, to wait for a response to a keepalive before
retransmitting. A value of zero uses the system default. If <TT
CLASS="SYMBOL"
>TCP_KEEPINTVL</TT
>
is not supported, this parameter must be zero. This parameter is ignored
for connections made via a Unix-domain socket.
</P
></DD
><DT
><A
NAME="GUC-TCP-KEEPALIVES-COUNT"
></A
><TT
CLASS="VARNAME"
>tcp_keepalives_count</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> On systems that support the <TT
CLASS="SYMBOL"
>TCP_KEEPCNT</TT
> socket option, specifies how
many keepalives can be lost before the connection is considered dead.
A value of zero uses the system default. If <TT
CLASS="SYMBOL"
>TCP_KEEPCNT</TT
> is not
supported, this parameter must be zero. This parameter is ignored
for connections made via a Unix-domain socket.
</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="RUNTIME-CONFIG-CONNECTION-SECURITY"
>18.3.2. Security and Authentication</A
></H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><A
NAME="GUC-AUTHENTICATION-TIMEOUT"
></A
><TT
CLASS="VARNAME"
>authentication_timeout</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Maximum time to complete client authentication, in seconds. If a
would-be client has not completed the authentication protocol in
this much time, the server breaks the connection. This prevents
hung clients from occupying a connection indefinitely.
The default is one minute (<TT
CLASS="LITERAL"
>1m</TT
>).
This parameter can only be set in the <TT
CLASS="FILENAME"
>postgresql.conf</TT
>
file or on the server command line.
</P
></DD
><DT
><A
NAME="GUC-SSL"
></A
><TT
CLASS="VARNAME"
>ssl</TT
> (<TT
CLASS="TYPE"
>boolean</TT
>)</DT
><DD
><P
> Enables <ACRONYM
CLASS="ACRONYM"
>SSL</ACRONYM
> connections. Please read
<A
HREF="ssl-tcp.html"
>Section 17.8</A
> before using this. The default
is <TT
CLASS="LITERAL"
>off</TT
>. This parameter can only be set at server
start. <ACRONYM
CLASS="ACRONYM"
>SSL</ACRONYM
> communication is only possible with
TCP/IP connections.
</P
></DD
><DT
><A
NAME="GUC-SSL-RENEGOTIATION-LIMIT"
></A
><TT
CLASS="VARNAME"
>ssl_renegotiation_limit</TT
> (<TT
CLASS="TYPE"
>integer</TT
>)</DT
><DD
><P
> Specifies how much data can flow over an <ACRONYM
CLASS="ACRONYM"
>SSL</ACRONYM
> encrypted connection
before renegotiation of the session will take place. Renegotiation of the
session decreases the chance of doing cryptanalysis when large amounts of data
are sent, but it also carries a large performance penalty. The sum of
sent and received traffic is used to check the limit. If the parameter is
set to 0, renegotiation is disabled. The default is <TT
CLASS="LITERAL"
>512MB</TT
>.
</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> SSL libraries from before November 2009 are insecure when using SSL
renegotiation, due to a vulnerability in the SSL protocol. As a stop-gap fix
for this vulnerability, some vendors also shipped SSL libraries incapable
of doing renegotiation. If any of these libraries are in use on the client
or server, SSL renegotiation should be disabled.
</P
></BLOCKQUOTE
></DIV
></DD
><DT
><A
NAME="GUC-SSL-CIPHERS"
></A
><TT
CLASS="VARNAME"
>ssl_ciphers</TT
> (<TT
CLASS="TYPE"
>string</TT
>)</DT
><DD
><P
> Specifies a list of <ACRONYM
CLASS="ACRONYM"
>SSL</ACRONYM
> ciphers that are allowed to be
used on secure connections. See the <SPAN
CLASS="APPLICATION"
>openssl</SPAN
>
manual page for a list of supported ciphers. This parameter is
unavailable unless the server is compiled with support for SSL.
</P
></DD
><DT
><A
NAME="GUC-PASSWORD-ENCRYPTION"
></A
><TT
CLASS="VARNAME"
>password_encryption</TT
> (<TT
CLASS="TYPE"
>boolean</TT
>)</DT
><DD
><P
> When a password is specified in <A
HREF="sql-createuser.html"
><I
>CREATE USER</I
></A
> or
<A
HREF="sql-alteruser.html"
><I
>ALTER USER</I
></A
>
without writing either <TT
CLASS="LITERAL"
>ENCRYPTED</TT
> or
<TT
CLASS="LITERAL"
>UNENCRYPTED</TT
>, this parameter determines whether the
password is to be encrypted. The default is <TT
CLASS="LITERAL"
>on</TT
>
(encrypt the password).
</P
></DD
><DT
><A
NAME="GUC-KRB-SERVER-KEYFILE"
></A
><TT
CLASS="VARNAME"
>krb_server_keyfile</TT
> (<TT
CLASS="TYPE"
>string</TT
>)</DT
><DD
><P
> Sets the location of the Kerberos server key file. See
<A
HREF="auth-methods.html#KERBEROS-AUTH"
>Section 19.3.5</A
> or <A
HREF="auth-methods.html#GSSAPI-AUTH"
>Section 19.3.3</A
>
for details. This parameter can only be set in the
<TT
CLASS="FILENAME"
>postgresql.conf</TT
> file or on the server command line.
</P
></DD
><DT
><A
NAME="GUC-KRB-SRVNAME"
></A
><TT
CLASS="VARNAME"
>krb_srvname</TT
> (<TT
CLASS="TYPE"
>string</TT
>)</DT
><DD
><P
> Sets the Kerberos service name. See <A
HREF="auth-methods.html#KERBEROS-AUTH"
>Section 19.3.5</A
>
for details. This parameter can only be set in the
<TT
CLASS="FILENAME"
>postgresql.conf</TT
> file or on the server command line.
</P
></DD
><DT
><A
NAME="GUC-KRB-CASEINS-USERS"
></A
><TT
CLASS="VARNAME"
>krb_caseins_users</TT
> (<TT
CLASS="TYPE"
>boolean</TT
>)</DT
><DD
><P
> Sets whether Kerberos and GSSAPI user names should be treated
case-insensitively.
The default is <TT
CLASS="LITERAL"
>off</TT
> (case sensitive). This parameter can only be
set in the <TT
CLASS="FILENAME"
>postgresql.conf</TT
> file or on the server command line.
</P
></DD
><DT
><A
NAME="GUC-DB-USER-NAMESPACE"
></A
><TT
CLASS="VARNAME"
>db_user_namespace</TT
> (<TT
CLASS="TYPE"
>boolean</TT
>)</DT
><DD
><P
> This parameter enables per-database user names. It is off by default.
This parameter can only be set in the <TT
CLASS="FILENAME"
>postgresql.conf</TT
>
file or on the server command line.
</P
><P
> If this is on, you should create users as <TT
CLASS="LITERAL"
>username@dbname</TT
>.
When <TT
CLASS="LITERAL"
>username</TT
> is passed by a connecting client,
<TT
CLASS="LITERAL"
>@</TT
> and the database name are appended to the user
name and that database-specific user name is looked up by the
server. Note that when you create users with names containing
<TT
CLASS="LITERAL"
>@</TT
> within the SQL environment, you will need to
quote the user name.
</P
><P
> With this parameter enabled, you can still create ordinary global
users. Simply append <TT
CLASS="LITERAL"
>@</TT
> when specifying the user
name in the client. The <TT
CLASS="LITERAL"
>@</TT
> will be stripped off
before the user name is looked up by the server.
</P
><P
> <TT
CLASS="VARNAME"
>db_user_namespace</TT
> causes the client's and
server's user name representation to differ.
Authentication checks are always done with the server's user name
so authentication methods must be configured for the
server's user name, not the client's. Because
<TT
CLASS="LITERAL"
>md5</TT
> uses the user name as salt on both the
client and server, <TT
CLASS="LITERAL"
>md5</TT
> cannot be used with
<TT
CLASS="VARNAME"
>db_user_namespace</TT
>.
</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> This feature is intended as a temporary measure until a
complete solution is found. At that time, this option will
be removed.
</P
></BLOCKQUOTE
></DIV
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