Good way to check firewall port on Linux centos 7

Hi,

I need to know what kind of firewall settings does the linux box have? Is port 25 blocked in any way?

Linux techx 3.10.0-514.10.2.el7.x86_64 #1 SMP Fri Mar 3 00:04:05 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

I'm coming from this thread.

Since this is a continuation of your already open thread, this is a duplicate and now closed.