PostgreSQL psql: could not connect to server: Connection refused

Posted on in Categories , , , , , last updated March 6, 2007

Q. When I try to connect remote PostgreSQL, I am reciving an error which read as follows:

psql: could not connect to server: Connection refused
Is the server running on host host.domain.com and accepting
TCP/IP connections on port 5432?

How do I fix this problem? I am using CentOS 4.x version.

A. First make sure PostgreSQL server has been started to remote server.

# /etc/init.d/postgresql start

If it is running and you get above error, you need to add enable TCP/IP support. By default, the PostgreSQL server only allows connections to the database from the local machine or localhost. This is a security feature.

Step # 1: Allow remote IP address to access PostgreSQL

You need to open file called /var/lib/pgsql/data/pg_hba.conf. Login as postgres user using su command:
$ su - postgres
$ vi /var/lib/pgsql/data/pg_hba.conf

Now append following line. Let us say you would like to give access to 192.168.1.0/24 network:
host all all 192.168.1.0 255.255.255.0 trust
Please replace 192.168.1.0 and 255.255.255.0 to reflect the actual network IP address range of the clients system in your own network.

Save close the file.

Step # 2: Allow communication over TCP/IP

You need to open PostgreSQL configuration file /var/lib/pgsql/data/postgresql.conf
$ vi /var/lib/pgsql/data/postgresql.conf
Now bind and open TCP/IP port by setting tcpip_socket to true:
tcpip_socket = true

Save and close the file.

Step # 3: Restart PostgreSQL server

Restart the PostgreSQL server with the following command
# /etc/init.d/postgresql restart

This will open default port 5432.

Step # 4: Test your setup

Use psql command from client system as follows:
psql -h PostgreSQL-IP-ADDRESS -U USERNAME -d DATABASENAME

Connect to remote server by IP address 192.168.1.5 and login using vivek user to connect to sales database, use:
$ psql -h 192.168.1.5 -U vivek -d sales
Where,

  • -h 192.168.1.5 : Specifies the host name of the machine or IP address (192.168.1.5) on which the server is running.
  • -U vivek : Connect to the database as the vivek username instead of the default. You must have account and permission to connect as vivek user.
  • -d sales : Specifies the name of the database (sales) to connect to.

See also:

=> How do I add a user to PostgreSQL database server?

PostgreSQL add or create a user account and grant permission for database

Posted on in Categories , , , , , , , last updated October 24, 2007

Q. How do I create a user account called tom and grant permission for database called jerry?

A. You need to use following commands.
=> adduser – UNIX/Linux adduser command to add a user to /etc/passwd file

=> psql => It is a terminal-based front-end to PostgreSQL.

=> CREATE USER – Adds a new user to a PostgreSQL database cluster.

=> CREATE DATABASE – create a new database

=> GRANT ALL PRIVILEGES – define access privileges

Procedure to add a user to PostgreSQL database

To create a normal user and an associated database you need to type the following commands. The easiest way to use is to create a Linux / UNUX IDENT authentication i.e. add user tom to UNIX or Linux system first.

Step # 1: Add a Linux/UNIX user called tom

Type the following commands to create a UNIX/Linux user called tom:
# adduser tom
# passwd tom

Step # 2: Becoming a superuser

You need to login as database super user under postgresql server. Again the simplest way to connect as the postgres user is to change to the postgres unix user on the database server using su command as follows:
# su - postgres

Step #3: Now connect to database server

Type the following command
$ psql template1
OR
$ psql -d template1 -U postgres
Output:

Welcome to psql 7.4.16, the PostgreSQL interactive terminal.

Type:  \\copyright for distribution terms
       \\h for help with SQL commands
       \\? for help on internal slash commands
       \\g or terminate with semicolon to execute query
       \\q to quit

template1=# 

Step #4: Add a user called tom

Type the following command to create a user called tom with a password called myPassword (you need to type command highlighted with red color):
template1=# CREATE USER tom WITH PASSWORD 'myPassword';

Step #5: Add a database called jerry

Type the following command (you need to type command highlighted with red color):
template1=# CREATE DATABASE jerry;
Now grant all privileges on database
template1=# GRANT ALL PRIVILEGES ON DATABASE jerry to tom;
Type \q to quit:
template1=# \q

Step #6: Test tom user login

In order to login as tom you need to type following commands. Login as tom or use su command:
$ su - tom
$ psql -d jerry -U tom

Output:

Welcome to psql 7.4.16, the PostgreSQL interactive terminal.

Type:  \\copyright for distribution terms
       \\h for help with SQL commands
       \\? for help on internal slash commands
       \\g or terminate with semicolon to execute query
       \\q to quit

jerry=>