Complete Guide to Secure Alpine Linux Using CSF Firewall

In this article, the Orcacore team tries to provide a step-by-step guide to Secure Alpine Linux Using CSF Firewall. Using CSF (ConfigServer Security & Firewall) on Alpine Linux will enhance the server’s security by providing advanced firewall management and monitoring capabilities. CSF allows server administrators to configure port access, monitor login attempts, and receive alerts for potential security issues. It will ensure that the server remains protected.

Now you can proceed to the following guide steps to Secure Alpine Linux Using CSF Firewall.

Steps To Secure Alpine Linux Using CSF Firewall

To Secure Alpine Linux Using CSF Firewall, you must have access to your server as a root user or a non-root user with sudo privileges. Then, proceed to the below steps to complete this guide.

Step 1 – Install CSF on Alpine Linux

To Secure Alpine Linux Using the CSF Firewall, you must add the Alpine Linux Edge Community Repository to Package Sources. The Alpine Linux Edge Community Repository is a rolling-release branch of Alpine Linux that provides access to the latest, cutting-edge software and updates.

Add Alpine Linux Edge Community Repository

Now you can add the Alpine Edge Community repository by using the following commands:

# echo "http://dl-cdn.alpinelinux.org/alpine/edge/main" > /etc/apk/repositories
# echo "http://dl-cdn.alpinelinux.org/alpine/edge/community" >> /etc/apk/repositories

Run System Update on Alpine Linux

Once you are done with adding the Edge repository, you must run the system update and upgrade on Alpine Linux with the following commands:

apk update && apk upgrade

Install Required Packages for CSF Setup

To secure Alpine Linux using CSF Firewall, you must install some required packages and dependencies. To do this, you can run the command below:

apk add wget iptables perl perl-libwww perl-time-hires

Download and Install CSF on Alpine

At this point, you must visit the CSF official website and download the latest package. To do this, you can navigate to your /opt directory and use the following wget command to download your package:

cd /opt & wget https://download.configserver.com/csf.tgz --no-check-certificate

Once your download is completed, extract your file, navigate to the CSF directory, and install CSF by using the commands below:

tar -xzf csf.tgz && cd csf && sh install.sh

Then, you can verify your CSF installation by running:

# cd /usr/local/csf/bin/ 
# perl csftest.pl

In your output, you should see the message RESULT: csf should function on this server.

Step 2 – Configure CSF Firewall on Alpine Linux

At this point, you must modify the CSF configuration. As you may know, the main CSF config file is /etc/csf/csf.conf. You must open the file with your desired text editor like Vi Editor or Nano Editor:

vi /etc/csf/csf.conf

At the file look for the Testing line and change its value to 0. This will enable the CSF Firewall:

TESTING = "0"

Also, you can open the following necessary ports:

TCP_IN = "22,80,443"
TCP_OUT = "22,80,443"

Once you are done, save and close the file.

To apply the changes, restart CSF on Alpine Linux:

csf -r

CSF Advanced Security Configuration on Alpine Linux

CSF can monitor login attempts and send email alerts. You can configure this in the csf.conf file by enabling login tracking settings:

LF_ALERT_TO = "your-email@example.com"

Also, you can limit the number of simultaneous connections to prevent DDoS attacks. This can be set up in the CSF configuration:

CT_LIMIT = "100"

Conclusion

As you saw, you can easily Secure Alpine Linux Using CSF Firewall. First, you need to add Edge Repo and easily download and install CSF on your Alpine Linux. CSF provides a complete set of tools to monitor traffic, manage firewall rules, and secure your server against potential threats.

Hope you enjoy using it. You may also like to read the following articles:

Modify Alpine Linux Hostname

Fix CSF Error: Warning Binary Location for HOST Incorrect

Fix: CSF Error Path to iptables Not Set or Incorrect

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