Be careful!!!I once blocked several countries in my /etc/csf/csf.conf.
CC_DENY = "CN,IN,RO,RU,BR,UA,NL,UK"
And then a few days later AutoSSL (renewal of SSL certificates) wasn't working anymore.
I WAS UNABLE to create new SSL certificates!
I've found out that blocking NL (Netherlands) was the root cause for it.
Let's Encrypt is located in NL and it needs to connect to generate SSL certificates!
Furthermore the support wrote me the following »
So keep that in mind