Steps to enable postgresql database to accept remote connections

Lab Excercise: Try to connect to our test database using test role/user through  pgAdmin version 4.29 console when postgres configured in a virtualbox with NAT network(port forwarded)

We need to do the following if we use virtualbox with NAT network alone.

OS details: Centos 7.9

Steps:

1) NAT network allow internet access but it doesnt allow incoming connections. Hence we setup port forwarding for it to work. Add a port forwarding in virtualbox console for the vm which we are testing.

127.0.0.1-54320 => VM's 5432 (ex. port for postgres)

2) Backup & Edit postgres.conf file, then enable both port & listen_address to '*'
3) Backup & Edit pg_hba.conf file, then make the below entry

host    all    all    10.0.0.0/16    md5

4) stop the firewall or add exception
a) stop the firewall - pgAdmin connects perfectly fine
b) Add exception via 
i) service [see below] - didnt work as expected the pgAdmin console was timing out always. Reason could be the netstat -plantu or ss -plantu didnt show the postgresql service against port we have postgres running, insteas it showed postgres. 

But firewall-cmd --get-service was showing postgresql as the service.

[root@localhost ~]# firewall-cmd --add-service=postgresql --permanent
success
[root@localhost ~]# firewall-cmd --list-all
public (active)
  target: default
  icmp-block-inversion: no
  interfaces: enp0s3
  sources:
  services: dhcpv6-client ssh
  ports:
  protocols:
  masquerade: no
  forward-ports:
  source-ports:
  icmp-blocks:
  rich rules:
[root@localhost ~]# firewall-cmd --reload
success
[root@localhost ~]# firewall-cmd --list-all
public (active)
  target: default
  icmp-block-inversion: no
  interfaces: enp0s3
  sources:
  services: dhcpv6-client postgresql ssh
  ports:
  protocols:
  masquerade: no
  forward-ports:
  source-ports:
  icmp-blocks:
  rich rules:
[root@localhost ~]#
[root@localhost ~]# firewall-cmd --get-service|tr " " "\n"
..
plex
pmcd
pmproxy
pmwebapi
pmwebapis
pop3
pop3s
postgresql
privoxy
..
zabbix-server
[root@localhost ~]#

ii) Try adding the port to exception - pgAdmin connects fine.

[root@localhost ~]# firewall-cmd --add-port=<port>/tcp --permanent
success
[root@localhost ~]# firewall-cmd --reload
success
[root@localhost ~]# firewall-cmd --list-all
public (active)
  target: default
  icmp-block-inversion: no
  interfaces: enp0s3
  sources:
  services: dhcpv6-client ssh
  ports: <port>/tcp
  protocols:
  masquerade: no
  forward-ports:
  source-ports:
  icmp-blocks:
  rich rules:
[root@localhost ~]#

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