How to whitelist IP from server firewall

To whitelist this on the other servers you can run the command:

apf -a 72.52.198.161

It will first need to be removed from the deny list first if it is being
blocked.

To remove the entry:

Run this command 

 
nano /etc/apf/deny_hosts.rules
Press control w to start a search, then enter the IP 72.52.198.161.

Once you find the location remove the two lines that the IP consist of, then
exit and save the file with control x and then y to save and exit.

After this run the command to restart the firewall:

/etc/init.d/apf restart