CentOS Linux OS Distribution
CentOS (https://www.centos.org/centos-linux/) is a Linux distribution developed by a gaggle of mutually-autonomous Special Interest Groups (SIG) coordinated through a Red Hat Governing Board. CentOS is derived from the Red Hat Enterprise Linux (RHEL) sources.1
Tornado VPS provides CentOS as a prebuilt image and a netboot install.
CentOS FAQ
Why can’t I connect to port 80?
The default firewall configuration in our CentOS image only allows connections on tcp port 22.
On CentOS 6, to allow connections to port 80, or any other port number, run
$ iptables -I RH-Firewall-1-INPUT 10 -m state --state NEW -p tcp --dport 80 -j ACCEPT
with the port number after --dport. You can also configure the firewall by
running system-config-securitylevel-tui. That’s going to make things a lot
easier from here on out.
By default, CentOS 7 uses firewalld for firewall management. To enable
inbound HTTP, you need to issue two commands using the firewall-cmd utility.
The first command only adds a new firewall rule to the running system, but
does not affect the permanent configuration. The second command makes the
configuration permanent. Those commands are:
$ firewall-cmd --add-service=http
$ firewall-cmd --permanent --add-service=http
Please see the firewall-cmd and firewalld manpages for more documentation.