RHEL 9

How to Detect Rootkits with rkhunter and chkrootkit on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Detect Rootkits with rkhunter and chkrootkit on RHEL 9

Rootkits are among the most dangerous forms of malware — they conceal themselves and other malicious software deep within the operating system, often modifying system binaries and kernel modules to hide their presence from standard tools. Detecting rootkits requires specialised scanners that check for known signatures, hidden files, suspicious processes, and tampered system binaries. This […]

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How to Configure nftables Firewall on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Configure nftables Firewall on RHEL 9

nftables is the modern successor to iptables and is the default firewall framework in RHEL 9. It replaces iptables, ip6tables, arptables, and ebtables with a single unified tool, offering better performance through an improved kernel path, atomic rule replacement, and a cleaner, more readable configuration syntax. This tutorial covers everything you need to know to […]

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How to Configure iptables Firewall Rules on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Configure iptables Firewall Rules on RHEL 9

iptables has been the standard Linux packet-filtering firewall for over two decades, and while RHEL 9 ships with nftables and firewalld as the preferred tools, iptables remains available and is widely understood by seasoned administrators. Learning iptables gives you deep insight into how Linux netfilter works and is valuable for managing legacy systems or containers […]

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How to Set Up Two-Factor Authentication for SSH with Google Authenticator on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Set Up Two-Factor Authentication for SSH with Google Authenticator on RHEL 9

Password-based SSH authentication is a well-known attack vector, and even key-based authentication can be compromised if a private key is stolen. Adding Time-Based One-Time Password (TOTP) two-factor authentication creates a second layer of defense that is independent of the key. This tutorial shows you how to configure the Google Authenticator PAM module on RHEL 9 […]

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How to Audit Linux Security with Lynis on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Audit Linux Security with Lynis on RHEL 9

Security auditing is a critical practice for any Linux administrator responsible for maintaining compliant and hardened systems. Lynis is a free, open-source security auditing tool that performs deep system scans and produces actionable hardening recommendations. On RHEL 9, Lynis integrates seamlessly and covers hundreds of security controls across authentication, networking, storage, and more. This tutorial […]

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How to Configure SELinux on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Configure SELinux on RHEL 9

SELinux (Security-Enhanced Linux) is a mandatory access control (MAC) framework built into the Linux kernel, developed by the NSA and now maintained as a core part of RHEL. Unlike traditional discretionary access control (DAC) where file permissions determine access, SELinux enforces policies that confine every process to the minimum resources it legitimately needs — even […]

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How to Install ClamAV Antivirus on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Install ClamAV Antivirus on RHEL 9

ClamAV is an open-source antivirus engine widely used on Linux servers to detect malware in files destined for Windows users — such as email attachments, uploaded documents, and shared network storage. While Linux systems are largely immune to the Windows malware that ClamAV detects, running it is a responsible practice wherever Linux servers act as […]

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How to Install and Configure OpenVPN on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Install and Configure OpenVPN on RHEL 9

OpenVPN is a mature, battle-tested VPN solution that supports TLS-based encryption and X.509 certificate authentication, making it well-suited for enterprise environments where certificate lifecycle management and strong mutual authentication are required. Unlike WireGuard, OpenVPN can traverse firewalls over TCP port 443, which is useful when UDP is blocked. On RHEL 9, OpenVPN 2.x is available […]

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How to Set Up WireGuard VPN on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Set Up WireGuard VPN on RHEL 9

WireGuard is a modern, high-performance VPN protocol built into the Linux kernel since version 5.6. It uses state-of-the-art cryptography (Curve25519, ChaCha20, Poly1305) and has a dramatically smaller codebase than older solutions like OpenVPN or IPsec, making it easier to audit and less prone to vulnerabilities. On RHEL 9, WireGuard support is available through the kernel […]

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How to Harden SSH on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Harden SSH on RHEL 9

SSH is the primary remote access method for Linux servers, making it a common target for brute-force attacks, credential stuffing, and exploitation attempts. On RHEL 9, the default OpenSSH configuration works out of the box but leaves several attack vectors open. Hardening your SSH server configuration significantly reduces the risk of unauthorized access and is […]

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