Open firewall port on CentOS 7

Use this command to find your active zone(s):

firewall-cmd --get-active-zones

It will say either public, dmz, or something else. You should only apply to the zones required.

In the case of public try:

firewall-cmd --zone=public --add-port=2888/tcp --permanent

Then remember to reload the firewall for changes to take effect.

firewall-cmd --reload

Otherwise, substitute public for your zone, for example, if your zone is dmz:

firewall-cmd --zone=dmz --add-port=2888/tcp --permanent

The answer by ganeshragav is correct, but it is also useful to know that you can use:

firewall-cmd --permanent --zone=public --add-port=2888/tcp

but if is a known service, you can use:

firewall-cmd --permanent --zone=public --add-service=http

and then reload the firewall

firewall-cmd --reload

[ Answer modified to reflect Martin Peter's comment, original answer had --permanent at end of command line ]

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