Installing and Configuring Config Server Firewall (CSF) in Ubuntu

Config Server Firewall (CSF) – a software product created for automatic server protection.

I’ll describe below the procedure for installing and configuring Config Server Firewall (CSF) in Ubuntu.

First of all, download the archive with the latest version:

cd /usr/src
sudo wget

Unpack the downloaded archive:

sudo tar -xzf csf.tgz

If any firewalls are used in the system, they must be disabled, iptables rules will be deleted automatically.
Disable for example UFW:

sudo ufw disable

Let’s move to the directory with the unpacked files and run the installer:

cd csf
sudo sh

Install the necessary components:

sudo apt-get install libwww-perl
perl -e "use Time::HiRes"

Check whether the required modules are installed (“OK” should be displayed opposite each):

sudo perl /usr/local/csf/bin/

After installation, the SSH port will be automatically opened, even if it is not standard, and your current address is added to the whitelist.
CSF will work in test mode, it will need to be disconnected later in the configuration file.
The configuration file can be opened in any text editor, for example nano:

sudo nano /etc/csf/csf.conf

The changes will be applied after the following command:

sudo csf -r

Lists of allowed and blocked IP addresses are located in /etc/csf/csf.allow, /etc/csf/csf.deny and /etc/csf/csf.ignore.

The status of the CSF can be seen by the command:

sudo csf --status

Delete CSF can be similar to the other script:

sudo -i
cd /etc/csf

The built-in brief help can be seen by the command:

man csf

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