pg_hba.conf File   Client authentication is controlled by a configuration file,
   which traditionally is named
   pg_hba.conf and is stored in the database
   cluster's data directory.
   (HBA stands for host-based authentication.) A default
   pg_hba.conf file is installed when the data
   directory is initialized by initdb.  It is
   possible to place the authentication configuration file elsewhere,
   however; see the hba_file configuration parameter.
  
   The general format of the pg_hba.conf file is
   a set of records, one per line. Blank lines are ignored, as is any
   text after the # comment character.
   Records cannot be continued across lines.
   A record is made
   up of a number of fields which are separated by spaces and/or tabs.
   Fields can contain white space if the field value is double-quoted.
   Quoting one of the keywords in a database, user, or address field (e.g.,
   all or replication) makes the word lose its special
   meaning, and just match a database, user, or host with that name.
  
Each record specifies a connection type, a client IP address range (if relevant for the connection type), a database name, a user name, and the authentication method to be used for connections matching these parameters. The first record with a matching connection type, client address, requested database, and user name is used to perform authentication. There is no “fall-through” or “backup”: if one record is chosen and the authentication fails, subsequent records are not considered. If no record matches, access is denied.
A record can have one of the seven formats
localdatabaseuserauth-method[auth-options] hostdatabaseuseraddressauth-method[auth-options] hostssldatabaseuseraddressauth-method[auth-options] hostnossldatabaseuseraddressauth-method[auth-options] hostdatabaseuserIP-addressIP-maskauth-method[auth-options] hostssldatabaseuserIP-addressIP-maskauth-method[auth-options] hostnossldatabaseuserIP-addressIP-maskauth-method[auth-options]
The meaning of the fields is as follows:
localThis record matches connection attempts using Unix-domain sockets. Without a record of this type, Unix-domain socket connections are disallowed.
host       This record matches connection attempts made using TCP/IP.
       host records match either
       SSL or non-SSL connection
       attempts.
      
       Remote TCP/IP connections will not be possible unless
       the server is started with an appropriate value for the
       listen_addresses configuration parameter,
       since the default behavior is to listen for TCP/IP connections
       only on the local loopback address localhost.
      
hostsslThis record matches connection attempts made using TCP/IP, but only when the connection is made with SSL encryption.
       To make use of this option the server must be built with
       SSL support. Furthermore,
       SSL must be enabled
       by setting the ssl configuration parameter (see
       Section 18.9 for more information).
       Otherwise, the hostssl record is ignored except for
       logging a warning that it cannot match any connections.
      
hostnossl       This record type has the opposite behavior of hostssl;
       it only matches connection attempts made over
       TCP/IP that do not use SSL.
      
database       Specifies which database name(s) this record matches.  The value
       all specifies that it matches all databases.
       The value sameuser specifies that the record
       matches if the requested database has the same name as the
       requested user.  The value samerole specifies that
       the requested user must be a member of the role with the same
       name as the requested database.  (samegroup is an
       obsolete but still accepted spelling of samerole.)
       Superusers are not considered to be members of a role for the
       purposes of samerole unless they are explicitly
       members of the role, directly or indirectly, and not just by
       virtue of being a superuser.
       The value replication specifies that the record
       matches if a physical replication connection is requested (note that
       replication connections do not specify any particular database).
       Otherwise, this is the name of
       a specific PostgreSQL database.
       Multiple database names can be supplied by separating them with
       commas.  A separate file containing database names can be specified by
       preceding the file name with @.
      
user       Specifies which database user name(s) this record
       matches. The value all specifies that it
       matches all users.  Otherwise, this is either the name of a specific
       database user, or a group name preceded by +.
       (Recall that there is no real distinction between users and groups
       in PostgreSQL; a + mark really means
       “match any of the roles that are directly or indirectly members
       of this role”, while a name without a + mark matches
       only that specific role.) For this purpose, a superuser is only
       considered to be a member of a role if they are explicitly a member
       of the role, directly or indirectly, and not just by virtue of
       being a superuser.
       Multiple user names can be supplied by separating them with commas.
       A separate file containing user names can be specified by preceding the
       file name with @.
      
addressSpecifies the client machine address(es) that this record matches. This field can contain either a host name, an IP address range, or one of the special key words mentioned below.
       An IP address range is specified using standard numeric notation
       for the range's starting address, then a slash (/)
       and a CIDR mask length.  The mask
       length indicates the number of high-order bits of the client
       IP address that must match.  Bits to the right of this should
       be zero in the given IP address.
       There must not be any white space between the IP address, the
       /, and the CIDR mask length.
      
       Typical examples of an IPv4 address range specified this way are
       172.20.143.89/32 for a single host, or
       172.20.143.0/24 for a small network, or
       10.6.0.0/16 for a larger one.
       An IPv6 address range might look like ::1/128
       for a single host (in this case the IPv6 loopback address) or
       fe80::7a31:c1ff:0000:0000/96 for a small
       network.
       0.0.0.0/0 represents all
       IPv4 addresses, and ::0/0 represents
       all IPv6 addresses.
       To specify a single host, use a mask length of 32 for IPv4 or
       128 for IPv6.  In a network address, do not omit trailing zeroes.
      
An entry given in IPv4 format will match only IPv4 connections, and an entry given in IPv6 format will match only IPv6 connections, even if the represented address is in the IPv4-in-IPv6 range. Note that entries in IPv6 format will be rejected if the system's C library does not have support for IPv6 addresses.
       You can also write all to match any IP address,
       samehost to match any of the server's own IP
       addresses, or samenet to match any address in any
       subnet that the server is directly connected to.
      
       If a host name is specified (anything that is not an IP address
       range or a special key word is treated as a host name),
       that name is compared with the result of a reverse name
       resolution of the client's IP address (e.g., reverse DNS
       lookup, if DNS is used).  Host name comparisons are case
       insensitive.  If there is a match, then a forward name
       resolution (e.g., forward DNS lookup) is performed on the host
       name to check whether any of the addresses it resolves to are
       equal to the client's IP address.  If both directions match,
       then the entry is considered to match.  (The host name that is
       used in pg_hba.conf should be the one that
       address-to-name resolution of the client's IP address returns,
       otherwise the line won't be matched.  Some host name databases
       allow associating an IP address with multiple host names, but
       the operating system will only return one host name when asked
       to resolve an IP address.)
      
       A host name specification that starts with a dot
       (.) matches a suffix of the actual host
       name.  So .example.com would match
       foo.example.com (but not just
       example.com).
      
       When host names are specified
       in pg_hba.conf, you should make sure that
       name resolution is reasonably fast.  It can be of advantage to
       set up a local name resolution cache such
       as nscd.  Also, you may wish to enable the
       configuration parameter log_hostname to see
       the client's host name instead of the IP address in the log.
      
       This field only applies to host,
       hostssl, and hostnossl records.
      
        Users sometimes wonder why host names are handled
        in this seemingly complicated way, with two name resolutions
        including a reverse lookup of the client's IP address.  This
        complicates use of the feature in case the client's reverse DNS
        entry is not set up or yields some undesirable host name.
        It is done primarily for efficiency: this way, a connection attempt
        requires at most two resolver lookups, one reverse and one forward.
        If there is a resolver problem with some address, it becomes only
        that client's problem.  A hypothetical alternative
        implementation that only did forward lookups would have to
        resolve every host name mentioned in
        pg_hba.conf during every connection attempt.
        That could be quite slow if many names are listed.
        And if there is a resolver problem with one of the host names,
        it becomes everyone's problem.
       
Also, a reverse lookup is necessary to implement the suffix matching feature, because the actual client host name needs to be known in order to match it against the pattern.
Note that this behavior is consistent with other popular implementations of host name-based access control, such as the Apache HTTP Server and TCP Wrappers.
IP-addressIP-mask       These two fields can be used as an alternative to the
       IP-address/mask-length
       notation.  Instead of
       specifying the mask length, the actual mask is specified in a
       separate column. For example, 255.0.0.0 represents an IPv4
       CIDR mask length of 8, and 255.255.255.255 represents a
       CIDR mask length of 32.
      
       These fields only apply to host,
       hostssl, and hostnossl records.
      
auth-methodSpecifies the authentication method to use when a connection matches this record. The possible choices are summarized here; details are in Section 20.3.
trustAllow the connection unconditionally. This method allows anyone that can connect to the PostgreSQL database server to login as any PostgreSQL user they wish, without the need for a password or any other authentication. See Section 20.3.1 for details.
reject          Reject the connection unconditionally. This is useful for
          “filtering out” certain hosts from a group, for example a
          reject line could block a specific host from connecting,
          while a later line allows the remaining hosts in a specific
          network to connect.
         
scram-sha-256Perform SCRAM-SHA-256 authentication to verify the user's password. See Section 20.3.2 for details.
md5Perform SCRAM-SHA-256 or MD5 authentication to verify the user's password. See Section 20.3.2 for details.
passwordRequire the client to supply an unencrypted password for authentication. Since the password is sent in clear text over the network, this should not be used on untrusted networks. See Section 20.3.2 for details.
gssUse GSSAPI to authenticate the user. This is only available for TCP/IP connections. See Section 20.3.3 for details.
sspiUse SSPI to authenticate the user. This is only available on Windows. See Section 20.3.4 for details.
identObtain the operating system user name of the client by contacting the ident server on the client and check if it matches the requested database user name. Ident authentication can only be used on TCP/IP connections. When specified for local connections, peer authentication will be used instead. See Section 20.3.5 for details.
peerObtain the client's operating system user name from the operating system and check if it matches the requested database user name. This is only available for local connections. See Section 20.3.6 for details.
ldapAuthenticate using an LDAP server. See Section 20.3.7 for details.
radiusAuthenticate using a RADIUS server. See Section 20.3.8 for details.
certAuthenticate using SSL client certificates. See Section 20.3.9 for details.
pamAuthenticate using the Pluggable Authentication Modules (PAM) service provided by the operating system. See Section 20.3.10 for details.
bsdAuthenticate using the BSD Authentication service provided by the operating system. See Section 20.3.11 for details.
auth-options       After the auth-method field, there can be field(s) of
       the form name=value that
       specify options for the authentication method. Details about which
       options are available for which authentication methods appear below.
      
       In addition to the method-specific options listed below, there is one
       method-independent authentication option clientcert, which
       can be specified in any hostssl record.  When set
       to 1, this option requires the client to present a valid
       (trusted) SSL certificate, in addition to the other requirements of the
       authentication method.
      
   Files included by @ constructs are read as lists of names,
   which can be separated by either whitespace or commas.  Comments are
   introduced by #, just as in
   pg_hba.conf, and nested @ constructs are
   allowed.  Unless the file name following @ is an absolute
   path, it is taken to be relative to the directory containing the
   referencing file.
  
   Since the pg_hba.conf records are examined
   sequentially for each connection attempt, the order of the records is
   significant. Typically, earlier records will have tight connection
   match parameters and weaker authentication methods, while later
   records will have looser match parameters and stronger authentication
   methods. For example, one might wish to use trust
   authentication for local TCP/IP connections but require a password for
   remote TCP/IP connections. In this case a record specifying
   trust authentication for connections from 127.0.0.1 would
   appear before a record specifying password authentication for a wider
   range of allowed client IP addresses.
  
   The pg_hba.conf file is read on start-up and when
   the main server process receives a
   SIGHUP
   signal. If you edit the file on an
   active system, you will need to signal the postmaster
   (using pg_ctl reload or kill -HUP) to make it
   re-read the file.
  
    The preceding statement is not true on Microsoft Windows: there, any
    changes in the pg_hba.conf file are immediately
    applied by subsequent new connections.
   
   The system view
   pg_hba_file_rules
   can be helpful for pre-testing changes to the pg_hba.conf
   file, or for diagnosing problems if loading of the file did not have the
   desired effects.  Rows in the view with
   non-null error fields indicate problems in the
   corresponding lines of the file.
  
    To connect to a particular database, a user must not only pass the
    pg_hba.conf checks, but must have the
    CONNECT privilege for the database.  If you wish to
    restrict which users can connect to which databases, it's usually
    easier to control this by granting/revoking CONNECT privilege
    than to put the rules in pg_hba.conf entries.
   
   Some examples of pg_hba.conf entries are shown in
   Example 20.1. See the next section for details on the
   different authentication methods.
  
Example 20.1. Example pg_hba.conf Entries
# Allow any user on the local system to connect to any database with # any database user name using Unix-domain sockets (the default for local # connections). # # TYPE DATABASE USER ADDRESS METHOD local all all trust # The same using local loopback TCP/IP connections. # # TYPE DATABASE USER ADDRESS METHOD host all all 127.0.0.1/32 trust # The same as the previous line, but using a separate netmask column # # TYPE DATABASE USER IP-ADDRESS IP-MASK METHOD host all all 127.0.0.1 255.255.255.255 trust # The same over IPv6. # # TYPE DATABASE USER ADDRESS METHOD host all all ::1/128 trust # The same using a host name (would typically cover both IPv4 and IPv6). # # TYPE DATABASE USER ADDRESS METHOD host all all localhost trust # Allow any user from any host with IP address 192.168.93.x to connect # to database "postgres" as the same user name that ident reports for # the connection (typically the operating system user name). # # TYPE DATABASE USER ADDRESS METHOD host postgres all 192.168.93.0/24 ident # Allow any user from host 192.168.12.10 to connect to database # "postgres" if the user's password is correctly supplied. # # TYPE DATABASE USER ADDRESS METHOD host postgres all 192.168.12.10/32 scram-sha-256 # Allow any user from hosts in the example.com domain to connect to # any database if the user's password is correctly supplied. # # Require SCRAM authentication for most users, but make an exception # for user 'mike', who uses an older client that doesn't support SCRAM # authentication. # # TYPE DATABASE USER ADDRESS METHOD host all mike .example.com md5 host all all .example.com scram-sha-256 # In the absence of preceding "host" lines, these two lines will # reject all connections from 192.168.54.1 (since that entry will be # matched first), but allow GSSAPI connections from anywhere else # on the Internet. The zero mask causes no bits of the host IP # address to be considered, so it matches any host. # # TYPE DATABASE USER ADDRESS METHOD host all all 192.168.54.1/32 reject host all all 0.0.0.0/0 gss # Allow users from 192.168.x.x hosts to connect to any database, if # they pass the ident check. If, for example, ident says the user is # "bryanh" and he requests to connect as PostgreSQL user "guest1", the # connection is allowed if there is an entry in pg_ident.conf for map # "omicron" that says "bryanh" is allowed to connect as "guest1". # # TYPE DATABASE USER ADDRESS METHOD host all all 192.168.0.0/16 ident map=omicron # If these are the only three lines for local connections, they will # allow local users to connect only to their own databases (databases # with the same name as their database user name) except for administrators # and members of role "support", who can connect to all databases. The file # $PGDATA/admins contains a list of names of administrators. Passwords # are required in all cases. # # TYPE DATABASE USER ADDRESS METHOD local sameuser all md5 local all @admins md5 local all +support md5 # The last two lines above can be combined into a single line: local all @admins,+support md5 # The database column can also use lists and file names: local db1,db2,@demodbs all md5