This article lists down the suggestions to resolve the below FATAL error that is encountered when establishing a connection to Postgres DB. 

Error: 
Cause: FATAL: no pg_hba.conf entry for host "10.XXX.1XX.1X", user "tdv_readyonly", database
"postgresdb", SSL off [Log ID: b9d7a290-27dd-484a-bbac-defec6db5769]

How to resolve Error "Cause: FATAL: no pg_hba.conf entry for host" while connecting to Postgres database?

Suggestion #1: In TIBCO Data Virtualization Studio, open the Postgres Data source and add 'sslmode=require' to the JDBC URL in the 'Connection URL Pattern' field. Save this change, close, and open the data source to test the connection. 
Example: jdbc:postgresql://<HOST>:<PORT>/<DATABASE_NAME>?sslmode=require

Suggestion #2: If the above suggestion does not help, remove it and follow the below steps: 
These steps have to be done at the Postgres DB side by the DBA.

(i). Add the following line in Postgresql.conf file:
listen_addresses = '*'

(ii). Add the following line at bottom of pg_hba.conf. This allows access to all databases for all users:
host  all  all xxx.xxx.xxx.xxx/32  md5

Note: Here, xxx.xxx.xxx.xxx is the IP address of the TIBCO Data Virtualization Server from where you are connecting to the PostgreSQL Database.

(iii). Restart PostgreSQL you are trying to connect to after making the above changes.