So long as you use the default configuration and only change the TESTING parameter in csf.conf then csf should work.
If it doesn't, it suggests a problem with the server environment (kernel, iptables or in the case of a VPS, the host node configuration of the VPS).
If the issue appears to be broken iptables connection tracking in the kernel (e.g. blocking allowed ports such as port 80 for http), try setting LF_SPI to "0" and then restarting csf and then lfd.
In the case of a VPS server, follow:
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