HowTo Safely Open a PostgreSQL Port for Remote Access?

This document describes how to open a PostgreSQL database port for remote access and includes security considerations for both Linux and Windows.

 

Why do you Need to Open a Port 

You need to open a remote port if you want to access data in the database from a client running on a different computer in the network. The same is true, if you want to use pgAdmin  for or similar tools for SQL development.

 

Check for Port IP

Please check if PostgreSQL is listening on a public port:

Linux:

# netstat -nlp | grep 5432

tcp        0      0 127.0.0.1:5432          0.0.0.0:*               LISTEN      1272/postgres
tcp6       0      0 ::1:5432                :::*                    LISTEN      1272/postgres 

Windows:

C:\>netstat -a | grep 5432

  TCP    127.0.0.1:5432         tarraco:0              LISTENING
  TCP    [::1]:5432             tarraco:0              LISTENING

The results above (including "127.0.0.1:5432") shows that PostgreSQL is listening only for connects originating from the local computer, so we will have to edit the "postgresql.conf" configuration file. A result including "0.0.0.0:5432" indicates that PostgreSQL is already listening for remote connections.

You can usually ignore the line with "::1", as it refers to the IP v6 protocol, which is rarely used.

 

Edit postgresql.conf

This file is usually located in /var/lib/pgsql/data/ on Linux or C:\PostgreSQL\data\ on Windows or similar.

In this file we will edit the "listen_address" and "port" parameters, so that they look like below: 

#------------------------------------------------------------------------------
# CONNECTIONS AND AUTHENTICATION
#------------------------------------------------------------------------------

# - Connection Settings -

listen_addresses = '0.0.0.0'		# what IP address(es) to listen on;
					# comma-separated list of addresses;
					# defaults to 'localhost'; use '*' for all
					# (change requires restart)
port = 5432				# (change requires restart)


Restart PostgreSQL

After that we need to restart PG to activate the changes.

On recent Linux system you have to enter as user root:

systemctl restart postgresql.service

On Windows you can use Control Panel -> Administrative Tools -> Services and restart the PostgreSQL service. For ]po[, the PostgreSQL service is called "]po[ PostgreSQL".

 

Repeating the "Check for Port IP" step above, you should now see that the port IP is "0.0.0.0", meaning that it will accept connections from any remote computer.

 

Authentication Configuration using pg_hba.conf

pg_hba.conf is located in the same directly as postgresql.conf. 

Please  add the following two lines at the end of the file:

host    all             all              0.0.0.0/0                       md5
host    all             all              ::/0                            md5

This means that remote access is allowed using IP v4 and IP v6 to all databases and all users using the "md5" authentication protocol.

Please "restart postgresql" again.

 

Open Linux Firewall Port

Does your PostgreSQL database run on a Linux server with the firewall enabled (like the [[https://sourceforge.net/projects/project-open/files/project-open/V5.0/|CentOS 7 ]project-open[ virtual appliance]])?

In this case you will have to poke a hole (as root):

# firewall-cmd --zone=public --add-port=5432/tcp --permanent
success
# firewall-cmd --reload
success 


Open Windows Firewall Port

Does your PostgreSQL database run on a Windows server with firewall enabled?

In this case you can just turn off the firewall for a first test in Control Panel -> Systems and Security -> Windows Firewall -> Turn Windows Firewall on or off.

As an alternative you can go to Control Panel -> Systems and Security ->  Windows Firewall -> Allow a program or feature through Windows Firewall -> Advanced Settings -> New Rule:

  • Rule Type: Port 
  • TCP or UDP: TCP
  • Specific local ports: 5432
  • Action: Allow the connection
  • When does this rule apply: Domain, Private and Public (all three checked)
  • Name: "PostgreSQL Incoming"

 

Setting PostgreSQL Passwords

In order to set the PostgreSQL password for the user "projop" (or whatever user...) you need to connect locally to the database using an account with administration rights.

In the ]project-open[ Centos 7 virtual appliance just enter "psql" in a local terminal window running as user "projop".

Then please issue the following SQL command:

alter user projop with password 'secret'; 

  

Connection Check via "psql"

Now you should be able to connect to the server using the standard PostgreSQL client "psql", the PG administration tool pgAdmin  or any other application with a PostgreSQL interface. We will check with the command line "psql" tool on the remote computer:

psql -h <server_ip> -U projop

As a result you should see "Password for user projop". This means that the port is open and active.

Then enter the "secret" password set above. 

An error message like "psql: could not connect to server: No route to host. Is the server running on host "192.168.0.10" and accepting TCP/IP connections on port 5432?" indicates that some of the steps above did not work out.

 


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