CSF is generally considered an advanced firewall given it has many more configuration options than most other software firewalls (such as APF). It’s also still simple enough to install and configure, even for novice system administrators. For a simple overview on how to install and configure CSF and its security plugin LFD (Login Failure Daemon), visit our tutorial.
Check CSF for Your IP Address
Let’s say that you want to check whether or not a specific IP address, maybe 220.127.116.11 , is blocked by CSF. That’s easy!
csf -g 18.104.22.168
Unblock an IP Address
If the IP address is denied in CSF and you want to remove it, then use this command:
csf -dr 22.214.171.124
CSF then needs to be restarted for the change to take effect: