Best 9 Linux Server Hardening Practices From Expert

Linux server hardening is really important to make your server too strong to handle third-party attacks. Companies and big organizations can save millions of dollars by protecting their server from cyberattacks.

As per Statistics, a website is hit more than 2 thousand times in a day by cyber attackers. So, on average, a website faces a cyberattack every 40 sec, and the total cost of cyberattacks is around $9.4 million.

The use of cloud computing and servers is continuously growing. This will result in more attacks. 

Here, we are required to implement the best Linux Server Hardening practices to protect our website, reduce cyberattacks, and secure data. Cyberattackers have many options to affect your website and you have to implement different security measures on the server for different purposes.

Look Also: Top 9 Docker Security Best Practices 

What is Linux Server Hardening?

Server Hardening is the process of making your server more strong than over. By implementing all Hardening best practices on your Linux server, you can reduce cyberattacks and secure your website or data from cyberattackers.

For example, if your website does not have a secure root access login then a cyberattacker will break it and you may lose all of your data or even your website.

As a website owner, you should optimize your system’s configuration for secure operation and data protection. A hardening follows a few rules including

• Remove things that aren’t needed for your server
• Update of software and application promptly
• Maintain a secure configuration setting
• Backing up your Linux Server
• Applying Disk Encryption

Linux server security becomes more important for you if you are setting up your own server. But when you choose a managed hosting or server then all the things are managed by the server provider.

Linux Server Hardening Best Practices

Because data and website are yours, you need to secure it as your own. We can divide the Server Hardening process into different processes. This includes 

• Linux Machine Level Hardening
• Linux Network Level Hardening
• Linux System Level Hardening
• Linux Alert Level Hardening

Each level includes a few basic Linux Server Hardening Best Practices that we will discuss in detail. So, let’s start

1. Encrypt Your Disk or Drive

Drive encryption is a security process to convert your readable website data into ciphertext code. No other user can access this file in a readable format without authorized permission.

Encryption is important to protect your data, keep it private, and irreversible data deletion. There are two types of drive encryption available including

1. Full Disk Encryption: This includes encryption of all your data, operating system, and application. Like BitLocker on Windows 
2. File-Level Encryption: Encrypt a particular file to protect it from access.

You can use “dm-crypt” for encryption. This can be installed by following the commands

For “dm-crypt” package installation on Red Hat/Fedora, you can use Command

yum install cryptsetup-luks

For “dm-crypt” package installation on Ubuntu or Debian itself), you can run the command

apt-get install cryptsetup

Once “dm-crypt” is installed on your system, you can begin the encryption process. Use this command for encryption

cryptsetup -y -v luksFormat (partition)

That’s not enough for encryption, you still have to follow several step during the encryption process.

But make sure to keep your encryption key protected, because loss of the encryption key will result in complete data loss.

2. Security of BIOS

BIOS (Basic Input/Output System) security is an important security measure to protect the BIOS firmware from unauthorized access, modification, and exploitation. BOIS is really helpful to start and off an operating system.

You can enable many features such as BIOS password protection, Secure Boot, and firmware integrity checks for security.

You should create a secure password that is different than all other previous passwords. After creating a new password, you can restrict the use of previous passwords with Linux.

3. System Updates

Updating your software and application is a system-level hardening process. We always need to update software or applications because a newer version of the software gives you better features including

• Protection against known threats
• Improve performance and stability
• patches that fix these vulnerabilities

You have to automate your system updates to avoid any important things. Take a backup of your software before updating and test the update to check properly working.

To properly update your server, you should use the RPM package manager. If you’re working with Red Hat blocks, you use “yum,” and if you’re working with Debian-based blocks, you use “apt-get.

• sudo apt update: To Perform system update for Debian/Ubuntu
• sudo yum update: To Perform system update for Red Hat/CentOS
• sudo dnf update: To Perform a system update for Fedora
• sudo pacman -Syu: To Perform system update for Arch Linux

You can configure Red Hat / CentOS / Fedora Linux to apply notifications via email. Also, the cron job is used to apply all security updates.

4. Root Login Security

Root login gives access to every resource and command to the person. From the root, anyone can manage, customize, and delete anything at any time. The security of root login is really crucial.

The best Linux security measure is to disable direct root login over SSH. This prevents users from logging in directly as root via SSH. You should use the SSH key for authentication and apply two-factor authentication on the account.

For tracking and better security, you should use “sudo” to execute any particular task when required. Sudo will give you the privilege to open your required files without sharing your root password and user credentials.

The other benefit is the tracking of executed steps. You can audit a complete journey of users through code. 

Everyone accessing the system remotely using protocols like FTP or SSH should log in with their own username, not as root.

5. Password Policies

Never creating a weak password is another crucial practice for Linux Server Hardening. Passwords are important to protect your website or server access from unauthorized persons. You should also apply two-factor authentication to add an extra layer of security.

You can also set a login notification whenever your account is logged in.

A strong password includes more than 8 characters with a mixture of alphabets, special characters, numbers, uppercase, etc. Also, few tools are available to help in securing passwords.

Another security option is to create a password aging for better security. Usually, Linux systems have their password policies in place to make changes to your password. You also have the option to stop it.

Either you have to use “chage” command to make any changes. Few commands such as:

• charge -M 99999 userName: Use this to disable the password
• charge -l userName: To get password info
• charge -E <expiry_date> username: To set up an expiry date
• charge -m <number_of_days> username: To set the maximum number of days

There is a file available in the setting called “/etc/login.defs” with all aging policies. Use this file to modify password policies.

One more thing, your password policies should restrict the use of previous passwords.

6. Linux Network Port Security

The Linux server network port is crucial to enable communication between the Linux server and the user’s device over the network. They allow services and applications running on the server to receive and respond to requests from external sources.

For example, a web server listens to all incoming HTTP requests on port 80, while an SSH server listens for SSH connections on port 22.

To secure open ports, you can implement the following practices:

• Consider the use of non-standard port numbers rather than default ports. Like 2222 port then 22 port for SSH.
• Restrict the access of the port for a particular IP address. 
• Disable Remote Root Logins that help to protect unknown login user activity.

In a simple way, you have to protect your open network port from attackers. You can identify which open ports are necessary and which ones can be safely disabled.

7. Firewall Configuration

A firewall is used to control incoming and outgoing traffic on your server based on the set rules. This is important to prevent unauthorized access to the server. A firewall can be hardware and software.

Examples include “iptables”, “firewalld” for Linux servers, and “ufw” (Uncomplicated Firewall), a user-friendly interface for managing “iptables”.

In the Linux kernel, “iptables” command allows to use firewall. With IPTables, you can filter traffic based on IP address which IP address to enter, which to reject, and what to forward.

Security-Enhanced Linux (SELinux) is a security module integrated into a Linux Kernel. This has three modes of firewall configuration based on filtration.

• Enforcing: A default configuration to filter only the right traffic.
• Permissive: Traffic will be monitored and logged
• Disabled: Nothing will be monitored and logged.

Consider configuring enforce SELinux to prevent unauthorized access. You can consider to use the following command to check the status of the configuration.

• sestatus

You can change it as needed.

8. Audit Configuration

Logging and auditing is an alert-level Linux server hardening practice. The server audit will provide information on hacking attempts, how many times when the threat occurred, and how protection works. 

This tool will keep a record of system calls, file accesses, and security events specified by the system administrator. 

• auditd: Used to write audit records to the disk.
• ausearch and aureport: searching and generating reports from audit logs to analyze recorded events.
• audispd: Configured to send audit events to external analysis tools

You have to regularly review audit logs to prevent the access use of disk space and ensure keep the history of all previous files.

Consider creating Secure Audit Logs to prevent the server from unauthorized access. Also, you can enable real-time alert Configuration to get notifications of any changes.

9. Log Configuration

Setting up logging mechanisms is useful to monitor various system activities, events, and behaviors. These logs will provide you with information including server posture, user activity, the performed events, and security incidents.

We can access log files from the /var/log directory. You can read the logs using the logwatch/logcheck command to monitor the details of logs.

• /var/log/messages – a general log for Linux systems 
• /var/log/auth.log – checking authentication-related events
• var/log/audit/audit.log – Know about system calls, processes, and user activities.
• /var/log/ufw.log: For firewall events, rule changes, and blocked connections
• /var/log/apache2/error.log: server-related issues and potential security threats

There are other lots of system configuration keys available to monitor security threats and ensure a secure Linux Server.

Hire Linux Server Administrator For Everything

Linux Server Hardening & Security is not an easy task that can be done by every individual. This requires a good technical knowledge of servers, Linux systems, and hardware. A small mistake may affect your server and cause website downtime.

Contact our Linux server team to ensure the best security possible for your website. We guarantee 100% protection from cyber attackers and ensure real-time monitoring. You should visit our outsource server support where we described it in detail. We are offering L1, L2, and L3 Linux server security to all individuals.

Conclusion

Linux server is widely adopted by all around the world. This is important to follow Linux Server Hardening best practices to make your server secure from all external and internal activity. Server security helps to win the trust of customers and sustain your website for a long time. Remember, do not compromise the security of the server if you have a website like software, banking, services, and e-commerce. There can be more Linux server security required to follow.

If do not have technical knowledge then you should hire a Linux Server administrator for better security.

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