A further note for anyone finding this - if you're using RHEL (as I am), use the 'setup' command to configure iptables. Following normal instructions for configuring it did not work to allow 5432 traffic.
Yes. RHEL always restricts with IPTables and SELinux. I use:
This allows me to disable both SElinux & IPtables on new systems and make sure I don't spend hours searching configuration files for the problem. Once I have everything the way I like it, I enable it and test.