By default Linux does not block any ports. You probably have some kind of a firewall running (shorewall?). So, you need to tell us what firewall you are running and someone will tell you how to unblock a port.
DT-Spirit, there's no way of telling you how to unblock a port on anywhere unless we know what you're using to block it. But if you're asking on why you're unable to access certain ports, then perhaps you might want to call your ISP and ask them that coz most of the time, linux servers do not come with a firewall unless installed by yourself or specifically requested.
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