RHEL Hardening: Because ‘YOLO’ Is Not a Security Strategy

Securing your Red Hat Enterprise Linux (RHEL) system is essential to protect sensitive data and maintain operational stability. Implementing strong security measures reduces vulnerabilities and strengthens your system against potential threats. Below are key steps to effectively harden your RHEL environment.

1. Keep Your System Updated

Regular updates ensure that security patches and performance improvements are applied.

sudo yum update -y

Keeping your system updated helps prevent exploitation of known vulnerabilities.

2. Minimize Installed Packages

Reducing the number of installed packages decreases the system’s attack surface. During installation, select a minimal setup, and remove unnecessary software:

sudo yum remove package-name

Less software means fewer potential vulnerabilities.

3. Configure User Accounts and Authentication

Implement strong password policies and limit administrative access.

• Disable Root Login via SSH:

  sudo vi /etc/ssh/sshd_config
  

  Set:

  PermitRootLogin no
  

• Enforce Strong Password Policies:

  sudo vi /etc/security/pwquality.conf
  

  Adjust minlen, dcredit, ucredit, and other values to strengthen password complexity.

These changes reduce the risk of unauthorized access.

4. Implement Firewall and Network Security

Use firewalld to control incoming and outgoing traffic:

sudo systemctl start firewalld
sudo systemctl enable firewalld

Configure zones and services according to your network’s needs. Also, disable unnecessary network services to limit entry points.

5. Enable SELinux

SELinux enforces mandatory access controls.

• Check Status:

  sestatus
  

• Set to Enforcing Mode:

  sudo vi /etc/selinux/config
  

  Ensure:

  SELINUX=enforcing
  

Enforcing mode helps prevent unauthorized actions by restricting process capabilities.

6. Secure SSH Access

Make SSH more secure by adjusting key configurations.

• Disable Password Authentication:

  sudo vi /etc/ssh/sshd_config
  

  Set:

  PasswordAuthentication no
  

• Change SSH Port:

  sudo vi /etc/ssh/sshd_config
  

  Set:

  Port 2222
  

Key-based authentication and a non-default port reduce the likelihood of brute-force attacks.

7. Configure System Logging and Auditing

Implement system-wide logging and auditing to detect and respond to suspicious activities.

• Install and Configure auditd:

  sudo yum install audit
  sudo systemctl start auditd
  sudo systemctl enable auditd
  

• Regularly Review Logs:

  sudo ausearch -m avc,user_avc,selinux_err,user_selinux_err -ts today
  

Reviewing logs regularly can help you catch and investigate unusual activity early.

8. Enable FIPS Mode

FIPS mode ensures that only approved cryptographic algorithms are used.

• Enable FIPS Mode:

  sudo fips-mode-setup --enable
  

• Verify FIPS Mode:

  fips-mode-setup --check
  

This is particularly important for organizations that require compliance with regulatory standards.

9. Implement File System Encryption

Protect sensitive data with disk encryption.

• Install LUKS:

  sudo yum install cryptsetup
  

• Set Up Encrypted Partition:

  sudo cryptsetup luksFormat /dev/sdX
  sudo cryptsetup luksOpen /dev/sdX encrypted_partition
  sudo mkfs.ext4 /dev/mapper/encrypted_partition
  sudo mount /dev/mapper/encrypted_partition /mnt
  

Encrypting storage ensures that data remains protected, even if physical drives are compromised.