Is your server under attack and looking for csf deny IP range option ?

ConfigServer Security and Firewall aka CSF work as one of the effective firewall configuration scripts.

It allows easy blocking of an entire range of IP addresses.

At Bobcares, we often receive requests block IP in CSF as a part of our Server Management Services.

Today, let us discuss how Support Engineers block IP range in CSF.

Use cases of CSF deny IP range

To begin with, let’s take a look at the typical use cases of denying IPs via CSF.

They include:

1. Blocking access from a malicious IP address range during server attack.
2. Restricting access to a particular set of users or network.
3. Setting country-based blocks.

How to deny IP range using CSF

Recently one of our customers wanted to block a range of IP from 2x.7x.214.0-2x.7x.215.255 in his cPanel server. Let’s discuss how our Support Engineers blocked the set of IP using CSF.

1. Using CSF command

For denying IP range from command line, we first SSH to the server.

Then to block a specific IP in CSF, we use the command:

csf -d 2x.7x.214.0

We can also temporarily block an IP using the command

csf -td 2x.7x.214.0

To block the IP range from 2x.7x.214.0-2x.7x.215.255, our Support Engineers calculate the CIDR for the IP range and block accordingly.

csf -d 2x.7x.214.0/23

Finally, we restart the CSF service using:

csf -r

In effect, we totally blocked access from the specified range of IP addresses.

2. Block from csf.deny file

Similarly, we can directly add the IP range entry in csf.deny file.

The file is located at /etc/csf/csf.deny. We open the file using the command

vi /etc/csf/csf.deny

We add the entry in the file to block the range 2x.7x.214.0-2x.7x.215.255.

2x.7x.214.0/23

Then we restart the CSF service

csf -r

3. From WHM

If WHM is available we can block an IP range from the panel itself. Let us discuss how our Support Engineers block an IP range.

We login to WHM and access the ConfigServer Security & Firewall.

In the Quick Deny section we enter the IP range. Now we click on Quick Deny.

Thus the IP range will be added to the csf.deny file in the server.

Once you receive the confirmation message click on Return.

That’s it. The firewall block is in place now.

[Trouble blocking IP range via CSF? We are here to help you.]

Conclusion

In short, CSF is one of the most effective firewall configurations. Today, we have discussed how our Support Engineers use the different methods to block IP range using CSF.