client authentication Since Pgpool-II is a middleware that works between PostgreSQL servers and a PostgreSQL database client, so when a client application connects to the Pgpool-II, Pgpool-II in turn connects to the PostgreSQL servers using the same credentials to serve the incoming client connection. Thus, all the access privileges and restrictions defined for the user in PostgreSQL gets automatically applied to all Pgpool-II clients, with an exceptions of the authentications on PostgreSQL side that depends on the client's IP addresses or host names. Reason being the connections to the PostgreSQL server are made by Pgpool-II on behalf of the connecting clients and PostgreSQL server can only see the IP address of the Pgpool-II server and not that of the actual client. Therefore, for the client host based authentications Pgpool-II has the pool_hba mechanism similar to the pg_hba mechanism for authenticating the incoming client connections. The pool_passwd file manages passwords for authentication used when clients connect to Pgpool-II (see for more details). The passwords registered on pool_passwd must match with the passwords registered on PostgreSQL. Note that passwords changed on PostgreSQL are not automatically sync to the passwords on pool_passwd. scram-shar-256 authentication and MD5 authentication require that the user name and the password have been already registered on pool_passwd, while clear text password authentication or does not require that. Therefore, if you want to avoid maintaining the pool_passwd, it would be worth to check clear text password authentication or . pool_hba.conf Just like the pg_hba.conf file for PostgreSQL, Pgpool-II supports a similar client authentication function using a configuration file called pool_hba.conf. If Pgpool-II is installed from source code, it also includes the sample pool_hba.conf.sample file in the default configuration directory ("/usr/local/etc"). By default, pool_hba authentication is disabled, and setting enable_pool_hba to on enables it. see the configuration parameter. If number of PostgreSQL servers is only one, or when running in raw mode (see ), pool_hba.conf is not necessary thus enable_pool_hba may be being set to off. In this case the client authentication method is completely managed by PostgreSQL. Also number of PostgreSQL servers is more than one, or not running in raw mode, enable_pool_hba may be being set to off as long as the authentication method defined by PostgreSQL is trust. The format of the pool_hba.conf file follows very closely PostgreSQL's pg_hba.conf format. The general format of the pool_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 following formats local database user auth-method auth-options host database user IP-address IP-mask auth-method auth-options hostssl database user IP-address IP-mask auth-method auth-options hostnossl database user IP-address IP-mask auth-method auth-options host database user address auth-method auth-options hostssl database user address auth-method auth-options hostnossl database user address auth-method auth-options The meaning of the fields is as follows: local This 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 configuration parameter, since the default behavior is to listen for TCP/IP connections only on the local loopback address localhost. hostssl This 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 Pgpool-II must be built with SSL support. Furthermore, SSL must be enabled by setting the configuration parameter. Otherwise, the hostssl record is ignored. 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. "samegroup" for database field is not supported: Since Pgpool-II does not know anything about users in the PostgreSQL backend server, the database name is simply compared against the entries in the database field of pool_hba.conf. user Specifies which database user name(s) this record matches. The value all specifies that it matches all users. Otherwise, this is the name of a specific database user group names following "+" for user field is not supported: This is for the same reason as for the "samegroup" of database field. A user name is simply checked against the entries in the user field of pool_hba.conf. address Specifies 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 pool_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 pool_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. This field only applies to host, hostssl, and hostnossl records. Specifying the host name in address field is not supported prior to Pgpool-II V3.7. IP-address IP-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. This field only applies to host, hostssl, and hostnossl records. auth-method Specifies the authentication method to use when a connection matches this record. The possible choices are summarized here; details are in . trust Allow the connection unconditionally. This method allows anyone that can connect to the Pgpool-II. reject Reject the connection unconditionally. This is useful for filtering out certain hosts, for example a reject line could block a specific host from connecting. md5 Require the client to supply a double-MD5-hashed password for authentication. To use md5 authentication, you need to register the user name and password in file. See for more details. If you don't want to manage password by using pool_passwd, you could use . scram-sha-256 Perform SCRAM-SHA-256 authentication to verify the user's password. To use scram-sha-256 authentication, you need to register the user name and password in file. See for more details. If you don't want to manage password by using pool_passwd, you could use . cert Authenticate using SSL client certificates. See for more details. pam Authenticate using the Pluggable Authentication Modules (PAM) service provided by the operating system. See for details. PAM authentication is supported using user information on the host where Pgpool-II is running. To enable PAM support the Pgpool-II must be configured with "--with-pam" To enable PAM authentication, you must create a service-configuration file for Pgpool-II in the system's PAM configuration directory (that is usually located at "/etc/pam.d"). A sample service-configuration file is also installed as "share/pgpool.pam" under the install directory. ldap Authenticate using LDAP server. See for more details. To enable LDAP support the Pgpool-II must be configured with "--with-ldap" auth-options After the auth-method field, there can be field(s) of the form name= value that specify options for the authentication method. Since the pool_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. All pool_hba authentication options described in this section are about the authentication taking place between a client and the Pgpool-II. A client still has to go through the PostgreSQL's authentication process and must have the CONNECT privilege for the database on the backend PostgreSQL server. As far as pool_hba is concerned, it does not matter if a user name and/or database name given by a client (i.e. psql -U testuser testdb) really exists in the backend. pool_hba only cares if a match in the pool_hba.conf can be found or not. Some examples of pool_hba.conf entries. See the next section for details on the different authentication methods. # 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 # 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 md5 The following subsections describe the authentication methods specified by pool_hba.conf in more detail. When trust authentication is specified, Pgpool-II assumes that anyone who can connect to the server is authorized to access connect with whatever database user name they specify. The method password sends the password in clear-text and is therefore vulnerable to password sniffing attacks. It should always be avoided if possible. If the connection is protected by SSL encryption then password can be used safely, though. For this sake, it is recommended to use hostssl in pool_hba.conf so that clients are enforced to use SSL encryption. A benefit to use the method is, the password for authentication is provided by client side and pool_passwd is not consulted. So you can avoid maintaining pool_passwd file. You can avoid maintaining pool_passwd by using as well but it does not enforce to use SSL encryption because pool_hba.conf cannot be used with the parameter. MD5 This authentication method is the password-based authentication methods in which MD-5-hashed password is sent by client. Since Pgpool-II does not has the visibility of PostgreSQL's database user password and client application only sends the MD5-hash of the password, so md5 authentication in Pgpool-II is supported using the authentication file. To use the md5 authentication authentication file must contain the user password in either plain text, AES or md5 encrypted format. The file should contain lines in the following format: "username:TEXT_plain_text_passwd" "username:AES_encrypted_passwd" "username:md5_encrypted_passwd" (Actually "_" after "TEXT", "AES" or "md5" does not exist.) MD5 here are the steps to enable md5 authentication: 1- Login as the database's operating system user and type "pg_md5 --config-file=path_to_pgpool.conf --md5auth --username=username password" user name and md5 encrypted password are registered into . If pool_passwd does not exist yet, pg_md5 command will automatically create it for you. user name and password must be identical to those registered in PostgreSQL server. 2- Add an appropriate md5 entry to pool_hba.conf. See for more details. If pool_hba.conf is not enabled, make sure that md5 authentication is specified in pg_hba.conf of PostgreSQL. 3- After changing md5 password (in both pool_passwd and PostgreSQL of course), reload the pgpool configurations. SCRAM This authentication method also known as SCRAM is a challenge-response based authentication that prevents the password sniffing on untrusted connections. Since Pgpool-II does not has the visibility of PostgreSQL's database user password, so SCRAM authentication is supported using the authentication file. To use the SCRAM authentication authentication file must contain the user password in either plain text or AES encrypted format. "username:TEXT_plain_text_passwd" "username:AES_encrypted_passwd" (Actually "_" after "TEXT" or "AES" does not exist.) md5 type user passwords in file can't be used for scram authentication SCRAM Here are the steps to enable scram-sha-256 authentication: 1- Create file entry for database user and password in plain text or AES encrypted format. The utility that comes with Pgpool-II can be used to create the AES encrypted password entries in the file. User name and password must be identical to those registered in the PostgreSQL server. 2- Add an appropriate scram-sha-256 entry to pool_hba.conf. See for more details. If pool_hba.conf is not enabled, make sure that md5 authentication is specified in pg_hba.conf of PostgreSQL. 3- After changing SCRAM password (in both pool_passwd and PostgreSQL of course), reload the Pgpool-II configuration. Certificate This authentication method uses SSL client certificates to perform authentication. It is therefore only available for SSL connections. When using this authentication method, the Pgpool-II will require that the client provide a valid certificate. No password prompt will be sent to the client. The cn (Common Name) attribute of the certificate will be compared to the requested database user name, and if they match the login will be allowed. The certificate authentication works between only client and Pgpool-II. The certificate authentication does not work between Pgpool-II and PostgreSQL. For backend authentication you can use any other authentication method. PAM This authentication method uses PAM (Pluggable Authentication Modules) as the authentication mechanism. The default PAM service name is pgpool. PAM authentication is supported using user information on the host where Pgpool-II is executed. For more information about PAM, please read the Linux-PAM Page. To enable PAM authentication, you need to create a service-configuration file named for Pgpool-II in the system's PAM configuration directory (which is usually at "/etc/pam.d"). To enable PAM support the Pgpool-II must be configured with "--with-pam" LDAP This authentication method uses LDAP as the password certification method. LDAP is used only to validate the user name/password pairs. Therefore the user must already exist in the database before LDAP can be used for authentication. LDAP authentication can operate in two modes. In the first mode, which we will call the simple bind mode, the server will bind to the distinguished name constructed as prefix username suffix. Typically, the prefix parameter is used to specify cn=, or DOMAIN\ in an Active Directory environment. suffix is used to specify the remaining part of the DN in a non-Active Directory environment. In the second mode, which we will call the search+bind mode, the server first binds to the LDAP directory with a fixed user name and password, specified with ldapbinddn and ldapbindpasswd, and performs a search for the user trying to log in to the database. If no user and password is configured, an anonymous bind will be attempted to the directory. The search will be performed over the subtree at ldapbasedn, and will try to do an exact match of the attribute specified in ldapsearchattribute. Once the user has been found in this search, the server disconnects and re-binds to the directory as this user, using the password specified by the client, to verify that the login is correct. This mode is the same as that used by LDAP authentication schemes in other software, such as Apache mod_authnz_ldap and pam_ldap. This method allows for significantly more flexibility in where the user objects are located in the directory, but will cause two separate connections to the LDAP server to be made. The following configuration options are used in both modes: ldapserver Names or IP addresses of LDAP servers to connect to. Multiple servers may be specified, separated by spaces. ldapport Port number on LDAP server to connect to. If no port is specified, the LDAP library's default port setting will be used. ldapscheme Set to ldaps to use LDAPS. This is a non-standard way of using LDAP over SSL, supported by some LDAP server implementations. See also the ldaptls option for an alternative. ldaptls Set to 1 to make the connection between Pgpool-II and the LDAP server use TLS encryption. This uses the StartTLS operation per RFC 4513. See also the ldapscheme option for an alternative. Note that using ldapscheme or ldaptls only encrypts the traffic between the Pgpool-II server and the LDAP server. The connection between the Pgpool-II server and the client will still be unencrypted unless SSL is used there as well. The following options are used in simple bind mode only: ldapprefix String to prepend to the user name when forming the DN to bind as, when doing simple bind authentication. ldapsuffix String to append to the user name when forming the DN to bind as, when doing simple bind authentication. The following options are used in search+bind mode only: ldapbasedn Root DN to begin the search for the user in, when doing search+bind authentication. ldapbinddn DN of user to bind to the directory with to perform the search when doing search+bind authentication. ldapbindpasswd Password for user to bind to the directory with to perform the search when doing search+bind authentication. ldapsearchattribute Attribute to match against the user name in the search when doing search+bind authentication. If no attribute is specified, the uid attribute will be used. ldapsearchfilter The search filter to use when doing search+bind authentication. Occurrences of $username will be replaced with the user name. This allows for more flexible search filters than ldapsearchattribute. ldapurl An RFC 4516 LDAP URL. This is an alternative way to write some of the other LDAP options in a more compact and standard form. The format is ldap[s]://host[:port]/basedn[?[attribute][?[scope][?[filter]]]] scope must be one of base, one, sub, typically the last. (The default is base, which is normally not useful in this application.) attribute can nominate a single attribute, in which case it is used as a value for ldapsearchattribute. If attribute is empty then filter can be used as a value for ldapsearchfilter. The URL scheme ldaps chooses the LDAPS method for making LDAP connections over SSL, equivalent to using ldapscheme=ldaps. To use encrypted LDAP connections using the StartTLS operation, use the normal URL scheme ldap and specify the ldaptls option in addition to ldapurl. For non-anonymous binds, ldapbinddn and ldapbindpasswd must be specified as separate options. backend_use_passwd Set to 1 to make the password used for LDAP authentication use authentication between Pgpool-II and backend. It is an error to mix configuration options for simple bind with options for search+bind. When using search+bind mode, the search can be performed using a single attribute specified with ldapsearchattribute, or using a custom search filter specified with ldapsearchfilter. Specifying ldapsearchattribute=foo is equivalent to specifying ldapsearchfilter="(foo=$username)". If neither option is specified the default is ldapsearchattribute=uid. If Pgpool-II was compiled with OpenLDAP as the LDAP client library, the ldapserver setting may be omitted. In that case, a list of host names and ports is looked up via RFC 2782 DNS SRV records. The name _ldap._tcp.DOMAIN is looked up, where DOMAIN is extracted from ldapbasedn. Here is an example for a simple-bind LDAP configuration: host ... ldap ldapserver=ldap.example.net ldapprefix="cn=" ldapsuffix=", dc=example, dc=net" When a connection to the database server as database user foo is requested, Pgpool-II will attempt to bind to the LDAP server using the DN cn=foo, dc=example, dc=net and the password provided by the client. If that connection succeeds, the database access is granted. Here is an example for a search+bind configuration: host ... ldap ldapserver=ldap.example.net ldapbasedn="dc=example, dc=net" ldapsearchattribute=uid When a connection to the database server as database user foo is requested, Pgpool-II will attempt to bind anonymously (since ldapbinddn was not specified) to the LDAP server, perform a search for (uid=foo) under the specified base DN. If an entry is found, it will then attempt to bind using that found information and the password supplied by the client. If that second connection succeeds, the database access is granted. Here is the same search+bind configuration written as a URL: host ... ldap ldapurl="ldap://ldap.example.net/dc=example,dc=net?uid?sub" Some other software that supports authentication against LDAP uses the same URL format, so it will be easier to share the configuration. Here is an example for a search+bind configuration that uses ldapsearchfilter instead of ldapsearchattribute to allow authentication by user ID or email address: host ... ldap ldapserver=ldap.example.net ldapbasedn="dc=example, dc=net" ldapsearchfilter="(|(uid=$username)(mail=$username))" Here is an example for a search+bind configuration that uses DNS SRV discovery to find the host name(s) and port(s) for the LDAP service for the domain name example.net: host ... ldap ldapbasedn="dc=example,dc=net" Since LDAP often uses commas and spaces to separate the different parts of a DN, it is often necessary to use double-quoted parameter values when configuring LDAP options, as shown in the examples. To enable LDAP support the Pgpool-II must be configured with "--with-ldap" GSSAPI GSSAPI is an industry-standard protocol for secure authentication defined in RFC 2743. Currently Pgpool-II does not support GSSAPI. Clients should not use GSSAPI authentication, or should use "prefer GSSAPI authentication if possible" option (this is the default setting of PostgreSQL clients). If latter is chosen, Pgpool-II requests non-GSSAPI authentication to client, and the clients will fall back to non-GSSAPI authentication method. Thus, usually users do not need to worry about that Pgpool-II does not accept GSSAPI authentication. AUTH Since Pgpool-IIV4.0 it possible to use different authentication for client application and backend PostgreSQL servers. For example, a client application can use scram-sha-256 to connect to Pgpool-II which in turn can use trust or md5 authentication to connect to PostgreSQL backend for the same session. AUTH SCRAM authentication guards against the man-in-the-middle type of attack, so Pgpool-II requires the user password to authenticate with the PostgreSQL backend. However, storing the clear text passwords in the "pool_passwd" file is not a good idea. You can instead store AES256 AES256 encrypted passwords, which will be used for authentication. The password is first encrypted using the AES256 encryption with the user provided key and then the encrypted password is base64 encoded and an AES prefix is added to the encoded string. You can use the utility to create the properly formatted AES256 encrypted password. can be used to create AES encrypted password entries in file. requires the key for encrypting the password entries. Later that same key will be required by Pgpool-II to decrypt the passwords to use for authentication. Pgpool-II must be built with SSL (--with-openssl) support to use the encrypted password feature. If you have AES encrypted passwords stored in the file, then Pgpool-II will require the decryption key to decrypt the passwords before using them, Pgpool-II tries to read the decryption key at startup from the .pgpoolkey file. pgpoolkey PGPOOLKEYFILE .pgpoolkey is a plain text file which contains the decryption key string. By default the Pgpool-II will look for the .pgpoolkey file in the user's home directory or the file referenced by environment variable PGPOOLKEYFILE. You can also specify the key file using the (-k, --key-file=KEY_FILE) command line argument to the command. The permissions on .pgpoolkey must disallow any access to world or group. Change the file permissions by the command chmod 0600 ~/.pgpoolkey.