listen_addresses (string)
      
       #
         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 *
         corresponds to all available IP interfaces.  The entry
         0.0.0.0 allows listening for all IPv4 addresses and
         :: allows listening for all IPv6 addresses.
         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.  If the list is not empty, the server will start if it
         can listen on at least one TCP/IP address.  A warning will be
         emitted for any TCP/IP address which cannot be opened.
         The default value is localhost,
         which allows only local TCP/IP “loopback” connections to be
         made.
       
         While client authentication (Chapter 20) allows fine-grained control
         over who can access the server, listen_addresses
         controls which interfaces accept connection attempts, which
         can help prevent repeated malicious connection requests on
         insecure network interfaces.  This parameter can only be set
         at server start.
       
port (integer)
      
       #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.
max_connections (integer)
      
       #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 initdb). This parameter can only be set at server start.
        PostgreSQL sizes certain resources based directly on the value of
        max_connections. Increasing its value leads to
        higher allocation of those resources, including shared memory.
       
When running a standby server, you must set this parameter to the same or higher value than on the primary server. Otherwise, queries will not be allowed in the standby server.
reserved_connections (integer)
      
       #
        Determines the number of connection “slots” that are
        reserved for connections by roles with privileges of the
        pg_use_reserved_connections
        role.  Whenever the number of free connection slots is greater than
        superuser_reserved_connections but less than or
        equal to the sum of superuser_reserved_connections
        and reserved_connections, new connections will be
        accepted only for superusers and roles with privileges of
        pg_use_reserved_connections.  If
        superuser_reserved_connections or fewer connection
        slots are available, new connections will be accepted only for
        superusers.
       
        The default value is zero connections.  The value must be less than
        max_connections minus
        superuser_reserved_connections.  This parameter can
        only be set at server start.
       
superuser_reserved_connections
      (integer)
      
       #
        Determines the number of connection “slots” that
        are reserved for connections by PostgreSQL
        superusers.  At most max_connections
        connections can ever be active simultaneously.  Whenever the
        number of active concurrent connections is at least
        max_connections minus
        superuser_reserved_connections, new
        connections will be accepted only for superusers.  The connection slots
        reserved by this parameter are intended as final reserve for emergency
        use after the slots reserved by
        reserved_connections have been exhausted.
       
        The default value is three connections. The value must be less
        than max_connections minus
        reserved_connections.
        This parameter can only be set at server start.
       
unix_socket_directories (string)
      
       #Specifies the directory of the Unix-domain socket(s) on which the server is to listen for connections from client applications. Multiple sockets can be created by listing multiple directories separated by commas. Whitespace between entries is ignored; surround a directory name with double quotes if you need to include whitespace or commas in the name. An empty value specifies not listening on any Unix-domain sockets, in which case only TCP/IP sockets can be used to connect to the server.
        A value that starts with @ specifies that a
        Unix-domain socket in the abstract namespace should be created
        (currently supported on Linux only).  In that case, this value
        does not specify a “directory” but a prefix from which
        the actual socket name is computed in the same manner as for the
        file-system namespace.  While the abstract socket name prefix can be
        chosen freely, since it is not a file-system location, the convention
        is to nonetheless use file-system-like values such as
        @/tmp.
       
        The default value is normally
        /tmp, but that can be changed at build time.
        On Windows, the default is empty, which means no Unix-domain socket is
        created by default.
        This parameter can only be set at server start.
       
        In addition to the socket file itself, which is named
        .s.PGSQL. where
        nnnnnnnn is the server's port number, an ordinary file
        named .s.PGSQL. will be
        created in each of the nnnn.lockunix_socket_directories directories.
        Neither file should ever be removed manually.
        For sockets in the abstract namespace, no lock file is created.
       
unix_socket_group (string)
      
       #
        Sets the owning group of the Unix-domain socket(s).  (The owning
        user of the sockets is always the user that starts the
        server.)  In combination with the parameter
        unix_socket_permissions this can be used as
        an additional access control mechanism for Unix-domain connections.
        By default this is the empty string, which uses the default
        group of the server user.  This parameter can only be set at
        server start.
       
This parameter is not supported on Windows. Any setting will be ignored. Also, sockets in the abstract namespace have no file owner, so this setting is also ignored in that case.
unix_socket_permissions (integer)
      
       #
        Sets the access permissions of the Unix-domain socket(s).  Unix-domain
        sockets use the usual Unix file system permission set.
        The parameter value is expected to be a numeric mode
        specified in the format accepted by the
        chmod and umask
        system calls.  (To use the customary octal format the number
        must start with a 0 (zero).)
       
        The default permissions are 0777, meaning
        anyone can connect. Reasonable alternatives are
        0770 (only user and group, see also
        unix_socket_group) and 0700
        (only user). (Note that for a Unix-domain socket, only write
        permission matters, so there is no point in setting or revoking
        read or execute permissions.)
       
This access control mechanism is independent of the one described in Chapter 20.
This parameter can only be set at server start.
        This parameter is irrelevant on systems, notably Solaris as of Solaris
        10, that ignore socket permissions entirely.  There, one can achieve a
        similar effect by pointing unix_socket_directories to a
        directory having search permission limited to the desired audience.
       
Sockets in the abstract namespace have no file permissions, so this setting is also ignored in that case.
bonjour (boolean)
      
       #Enables advertising the server's existence via Bonjour. The default is off. This parameter can only be set at server start.
bonjour_name (string)
      
       #
        Specifies the Bonjour service
        name.  The computer name is used if this parameter is set to the
        empty string '' (which is the default).  This parameter is
        ignored if the server was not compiled with
        Bonjour support.
        This parameter can only be set at server start.
       
tcp_keepalives_idle (integer)
      
       #
        Specifies the amount of time with no network activity after which
        the operating system should send a TCP keepalive message to the client.
        If this value is specified without units, it is taken as seconds.
        A value of 0 (the default) selects the operating system's default.
        On Windows, setting a value of 0 will set this parameter to 2 hours,
        since Windows does not provide a way to read the system default value.
        This parameter is supported only on systems that support
        TCP_KEEPIDLE or an equivalent socket option, and on
        Windows; on other systems, it must be zero.
        In sessions connected via a Unix-domain socket, this parameter is
        ignored and always reads as zero.
       
tcp_keepalives_interval (integer)
      
       #
        Specifies the amount of time after which a TCP keepalive message
        that has not been acknowledged by the client should be retransmitted.
        If this value is specified without units, it is taken as seconds.
        A value of 0 (the default) selects the operating system's default.
        On Windows, setting a value of 0 will set this parameter to 1 second,
        since Windows does not provide a way to read the system default value.
        This parameter is supported only on systems that support
        TCP_KEEPINTVL or an equivalent socket option, and on
        Windows; on other systems, it must be zero.
        In sessions connected via a Unix-domain socket, this parameter is
        ignored and always reads as zero.
       
tcp_keepalives_count (integer)
      
       #
        Specifies the number of TCP keepalive messages that can be lost before
        the server's connection to the client is considered dead.
        A value of 0 (the default) selects the operating system's default.
        This parameter is supported only on systems that support
        TCP_KEEPCNT or an equivalent socket option (which does not include Windows);
        on other systems, it must be zero.
        In sessions connected via a Unix-domain socket, this parameter is
        ignored and always reads as zero.
       
tcp_user_timeout (integer)
      
       #
        Specifies the amount of time that transmitted data may
        remain unacknowledged before the TCP connection is forcibly closed.
        If this value is specified without units, it is taken as milliseconds.
        A value of 0 (the default) selects the operating system's default.
        This parameter is supported only on systems that support
        TCP_USER_TIMEOUT (which does not include Windows); on other systems, it must be zero.
        In sessions connected via a Unix-domain socket, this parameter is
        ignored and always reads as zero.
       
client_connection_check_interval (integer)
      
       #Sets the time interval between optional checks that the client is still connected, while running queries. The check is performed by polling the socket, and allows long running queries to be aborted sooner if the kernel reports that the connection is closed.
This option relies on kernel events exposed by Linux, macOS, illumos and the BSD family of operating systems, and is not currently available on other systems.
        If the value is specified without units, it is taken as milliseconds.
        The default value is 0, which disables connection
        checks.  Without connection checks, the server will detect the loss of
        the connection only at the next interaction with the socket, when it
        waits for, receives or sends data.
       
For the kernel itself to detect lost TCP connections reliably and within a known timeframe in all scenarios including network failure, it may also be necessary to adjust the TCP keepalive settings of the operating system, or the tcp_keepalives_idle, tcp_keepalives_interval and tcp_keepalives_count settings of PostgreSQL.
authentication_timeout (integer)
      
      
      
       #
        Maximum amount of time allowed to complete client authentication. If a
        would-be client has not completed the authentication protocol in
        this much time, the server closes the connection. This prevents
        hung clients from occupying a connection indefinitely.
        If this value is specified without units, it is taken as seconds.
        The default is one minute (1m).
        This parameter can only be set in the postgresql.conf
        file or on the server command line.
       
password_encryption (enum)
      
       #
        When a password is specified in CREATE ROLE or
        ALTER ROLE, this parameter determines the
        algorithm to use to encrypt the password.  Possible values are
        scram-sha-256, which will encrypt the password with
        SCRAM-SHA-256, and md5, which stores the password
        as an MD5 hash.  The default is scram-sha-256.
       
Note that older clients might lack support for the SCRAM authentication mechanism, and hence not work with passwords encrypted with SCRAM-SHA-256. See Section 20.5 for more details.
scram_iterations (integer)
      
       #
        The number of computational iterations to be performed when encrypting
        a password using SCRAM-SHA-256. The default is 4096.
        A higher number of iterations provides additional protection against
        brute-force attacks on stored passwords, but makes authentication
        slower. Changing the value has no effect on existing passwords
        encrypted with SCRAM-SHA-256 as the iteration count is fixed at the
        time of encryption. In order to make use of a changed value, a new
        password must be set.
       
krb_server_keyfile (string)
      
       #
        Sets the location of the server's Kerberos key file.  The default is
        FILE:/usr/local/pgsql/etc/krb5.keytab
        (where the directory part is whatever was specified
        as sysconfdir at build time; use
        pg_config --sysconfdir to determine that).
        If this parameter is set to an empty string, it is ignored and a
        system-dependent default is used.
        This parameter can only be set in the
        postgresql.conf file or on the server command line.
        See Section 20.6 for more information.
       
krb_caseins_users (boolean)
      
       #
        Sets whether GSSAPI user names should be treated
        case-insensitively.
        The default is off (case sensitive). This parameter can only be
        set in the postgresql.conf file or on the server command line.
       
gss_accept_delegation (boolean)
      
       #
        Sets whether GSSAPI delegation should be accepted from the client.
        The default is off meaning credentials from the client will
        not be accepted.  Changing this to on will make the server
        accept credentials delegated to it from the client. This parameter can only be
        set in the postgresql.conf file or on the server command line.
       
      See Section 18.9 for more information about setting up
      SSL. The configuration parameters for controlling
      transfer encryption using TLS protocols are named
      ssl for historic reasons, even though support for
      the SSL protocol has been deprecated.
      SSL is in this context used interchangeably with
      TLS.
     
ssl (boolean)
      
       #
        Enables SSL connections.
        This parameter can only be set in the postgresql.conf
        file or on the server command line.
        The default is off.
       
ssl_ca_file (string)
      
       #
        Specifies the name of the file containing the SSL server certificate
        authority (CA).
        Relative paths are relative to the data directory.
        This parameter can only be set in the postgresql.conf
        file or on the server command line.
        The default is empty, meaning no CA file is loaded,
        and client certificate verification is not performed.
       
ssl_cert_file (string)
      
       #
        Specifies the name of the file containing the SSL server certificate.
        Relative paths are relative to the data directory.
        This parameter can only be set in the postgresql.conf
        file or on the server command line.
        The default is server.crt.
       
ssl_crl_file (string)
      
       #
        Specifies the name of the file containing the SSL client certificate
        revocation list (CRL).
        Relative paths are relative to the data directory.
        This parameter can only be set in the postgresql.conf
        file or on the server command line.
        The default is empty, meaning no CRL file is loaded (unless
        ssl_crl_dir is set).
       
ssl_crl_dir (string)
      
       #
        Specifies the name of the directory containing the SSL client
        certificate revocation list (CRL).  Relative paths are relative to the
        data directory.  This parameter can only be set in
        the postgresql.conf file or on the server command
        line.  The default is empty, meaning no CRLs are used (unless
        ssl_crl_file is set).
       
        The directory needs to be prepared with the
        OpenSSL command
        openssl rehash or c_rehash.  See
        its documentation for details.
       
When using this setting, CRLs in the specified directory are loaded on-demand at connection time. New CRLs can be added to the directory and will be used immediately. This is unlike ssl_crl_file, which causes the CRL in the file to be loaded at server start time or when the configuration is reloaded. Both settings can be used together.
ssl_key_file (string)
      
       #
        Specifies the name of the file containing the SSL server private key.
        Relative paths are relative to the data directory.
        This parameter can only be set in the postgresql.conf
        file or on the server command line.
        The default is server.key.
       
ssl_ciphers (string)
      
       #
        Specifies a list of SSL cipher suites that are
        allowed to be used by SSL connections.  See the
        ciphers
        manual page in the OpenSSL package for the
        syntax of this setting and a list of supported values.  Only
        connections using TLS version 1.2 and lower are affected.  There is
        currently no setting that controls the cipher choices used by TLS
        version 1.3 connections.  The default value is
        HIGH:MEDIUM:+3DES:!aNULL.  The default is usually a
        reasonable choice unless you have specific security requirements.
       
        This parameter can only be set in the
        postgresql.conf file or on the server command
        line.
       
Explanation of the default value:
HIGH #
            Cipher suites that use ciphers from HIGH group (e.g.,
            AES, Camellia, 3DES)
           
MEDIUM #
            Cipher suites that use ciphers from MEDIUM group
            (e.g., RC4, SEED)
           
+3DES #
            The OpenSSL default order for
            HIGH is problematic because it orders 3DES
            higher than AES128.  This is wrong because 3DES offers less
            security than AES128, and it is also much slower.
            +3DES reorders it after all other
            HIGH and MEDIUM ciphers.
           
!aNULL #Disables anonymous cipher suites that do no authentication. Such cipher suites are vulnerable to MITM attacks and therefore should not be used.
        Available cipher suite details will vary across
        OpenSSL versions.  Use the command
        openssl ciphers -v 'HIGH:MEDIUM:+3DES:!aNULL' to
        see actual details for the currently installed
        OpenSSL version.  Note that this list is
        filtered at run time based on the server key type.
       
ssl_prefer_server_ciphers (boolean)
      
       #
        Specifies whether to use the server's SSL cipher preferences, rather
        than the client's.
        This parameter can only be set in the postgresql.conf
        file or on the server command line.
        The default is on.
       
PostgreSQL versions before 9.4 do not have this setting and always use the client's preferences. This setting is mainly for backward compatibility with those versions. Using the server's preferences is usually better because it is more likely that the server is appropriately configured.
ssl_ecdh_curve (string)
      
       #
        Specifies the name of the curve to use in ECDH key
        exchange.  It needs to be supported by all clients that connect.
        It does not need to be the same curve used by the server's Elliptic
        Curve key.
        This parameter can only be set in the postgresql.conf
        file or on the server command line.
        The default is prime256v1.
       
        OpenSSL names for the most common curves
        are:
        prime256v1 (NIST P-256),
        secp384r1 (NIST P-384),
        secp521r1 (NIST P-521).
        The full list of available curves can be shown with the command
        openssl ecparam -list_curves.  Not all of them
        are usable in TLS though.
       
ssl_min_protocol_version (enum)
      
       #
        Sets the minimum SSL/TLS protocol version to use.  Valid values are
        currently: TLSv1, TLSv1.1,
        TLSv1.2, TLSv1.3.  Older
        versions of the OpenSSL library do not
        support all values; an error will be raised if an unsupported setting
        is chosen.  Protocol versions before TLS 1.0, namely SSL version 2 and
        3, are always disabled.
       
        The default is TLSv1.2, which satisfies industry
        best practices as of this writing.
       
        This parameter can only be set in the postgresql.conf
        file or on the server command line.
       
ssl_max_protocol_version (enum)
      
       #Sets the maximum SSL/TLS protocol version to use. Valid values are as for ssl_min_protocol_version, with addition of an empty string, which allows any protocol version. The default is to allow any version. Setting the maximum protocol version is mainly useful for testing or if some component has issues working with a newer protocol.
        This parameter can only be set in the postgresql.conf
        file or on the server command line.
       
ssl_dh_params_file (string)
      
       #
        Specifies the name of the file containing Diffie-Hellman parameters
        used for so-called ephemeral DH family of SSL ciphers. The default is
        empty, in which case compiled-in default DH parameters used. Using
        custom DH parameters reduces the exposure if an attacker manages to
        crack the well-known compiled-in DH parameters. You can create your own
        DH parameters file with the command
        openssl dhparam -out dhparams.pem 2048.
       
        This parameter can only be set in the postgresql.conf
        file or on the server command line.
       
ssl_passphrase_command (string)
      
       #Sets an external command to be invoked when a passphrase for decrypting an SSL file such as a private key needs to be obtained. By default, this parameter is empty, which means the built-in prompting mechanism is used.
        The command must print the passphrase to the standard output and exit
        with code 0.  In the parameter value, %p is
        replaced by a prompt string.  (Write %% for a
        literal %.)  Note that the prompt string will
        probably contain whitespace, so be sure to quote adequately.  A single
        newline is stripped from the end of the output if present.
       
The command does not actually have to prompt the user for a passphrase. It can read it from a file, obtain it from a keychain facility, or similar. It is up to the user to make sure the chosen mechanism is adequately secure.
        This parameter can only be set in the postgresql.conf
        file or on the server command line.
       
ssl_passphrase_command_supports_reload (boolean)
      
       #
        This parameter determines whether the passphrase command set by
        ssl_passphrase_command will also be called during a
        configuration reload if a key file needs a passphrase.  If this
        parameter is off (the default), then
        ssl_passphrase_command will be ignored during a
        reload and the SSL configuration will not be reloaded if a passphrase
        is needed.  That setting is appropriate for a command that requires a
        TTY for prompting, which might not be available when the server is
        running.  Setting this parameter to on might be appropriate if the
        passphrase is obtained from a file, for example.
       
        This parameter can only be set in the postgresql.conf
        file or on the server command line.