Entries in the pg_hba.conf file control network authentication and authorization. The pg_hba.conf file on the PEM server host must allow connections between the PEM server and PEM-HTTPD, the PEM agent, and the monitored servers.During the PEM server installation process, you are prompted for the IP address and connection information for hosts that will be monitored by PEM; this information is added to the top of the pg_hba.conf file of the PEM backing database (see Figure 6.3).You may also need to manually modify the pg_hba.conf file to allow connections between the PEM server and other components. For example, if your PEM-HTTPD installation does not reside on the same host as the PEM server, you must modify the pg_hba.conf file on the PEM server host to allowPEM-HTTPD to connect to the server.By default, the pg_hba.conf file resides in the data directory, under your Postgres installation; for example, on an Advanced Server 10 host, the default location of the pg_hba.conf is:You can modify the pg_hba.conf file with your editor of choice. After modifying the file, restart the server for changes to take effect.The following example shows a pg_hba.conf entry that allows an md5 password authenticated connection from a user named postgres, to the postgres database on the host on which the pg_hba.conf file resides. The connection is coming from an IP address of 192.168.10.102:You may specify the address of a network host, or a network address range. For example, if you wish to allow connections from servers with the addresses 192.168.10.23, 192.168.10.76 and 192.168.10.184, enter a CIDR-ADDRESS of 192.168.10.0/24 to allow connections from all of the hosts in that network:For more information about formatting a pg_hba.conf file entry, please see the PostgreSQL core documentation at:Before you can connect to a Postgres server with PEM, you must ensure that the pg_hba.conf file on both servers allows the connection (see Figure 6.4).If you receive this error when connecting to the database server, modify the pg_hba.conf file, adding an entry that allows the connection.