DNS

How to Configure SSL/TLS with OpenSSL and Self-Signed Certificates on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Configure SSL/TLS with OpenSSL and Self-Signed Certificates on RHEL 9

Even when free trusted certificates from Let’s Encrypt are available for public domains, self-signed certificates serve important roles: development environments, internal network services, IoT devices, automated testing pipelines, and machine-to-machine communication within a private network. Unlike Let’s Encrypt certificates, self-signed certificates require no domain ownership verification or outbound internet access — they can be generated […]

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How to Configure HAProxy for HTTP and TCP Load Balancing on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Configure HAProxy for HTTP and TCP Load Balancing on RHEL 9

HAProxy (High Availability Proxy) is a battle-hardened open-source load balancer and proxy for TCP and HTTP workloads. Where Nginx load balancing is sufficient for simple round-robin HTTP distribution, HAProxy provides a richer feature set: advanced health checks with multiple failure thresholds, ACL-based routing, Layer 4 TCP load balancing for non-HTTP protocols (MySQL, Redis, SMTP), detailed […]

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How to Configure Nginx Rate Limiting and Connection Throttling on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Configure Nginx Rate Limiting and Connection Throttling on RHEL 9

Rate limiting is a server-side defence that restricts how many requests a client can make within a time window. Without rate limiting, a single IP address or bot can flood your server with thousands of requests per second — crashing your application, exhausting your database connection pool, or triggering denial-of-service conditions. Nginx provides two rate […]

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How to Set Up ModSecurity WAF with Apache on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Set Up ModSecurity WAF with Apache on RHEL 9

ModSecurity is the leading open-source Web Application Firewall (WAF), capable of inspecting all HTTP requests and responses against a ruleset and blocking malicious traffic including SQL injection, cross-site scripting (XSS), remote file inclusion, and OWASP Top 10 attack patterns. Combined with the OWASP Core Rule Set (CRS), ModSecurity transforms Apache into a security gateway that […]

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How to Install and Configure Caddy Web Server on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Install and Configure Caddy Web Server on RHEL 9

Caddy is a modern, open-source web server written in Go that stands out for one defining feature: automatic HTTPS. Caddy obtains and renews TLS certificates from Let’s Encrypt or ZeroSSL automatically, with zero configuration required beyond specifying a domain name. It also supports HTTP/2 and HTTP/3 (QUIC) out of the box, and its declarative Caddyfile […]

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How to Secure Apache with Let's Encrypt and Certbot on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Secure Apache with Let’s Encrypt and Certbot on RHEL 9

Like Nginx, Apache can be secured with free SSL/TLS certificates from Let’s Encrypt using Certbot. The python3-certbot-apache plugin performs domain validation, obtains the certificate, and automatically updates your Apache virtual host configuration with the SSL directives, HTTP-to-HTTPS redirect, and modern cipher settings. This guide covers installing Certbot on RHEL 9, obtaining a certificate for your […]

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How to Secure Nginx with Let's Encrypt and Certbot on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Secure Nginx with Let’s Encrypt and Certbot on RHEL 9

HTTPS is no longer optional — browsers mark HTTP sites as “Not Secure”, search engines penalise them in rankings, and many modern browser APIs (service workers, geolocation, camera access) require a secure context. Let’s Encrypt provides free, automated, and trusted SSL/TLS certificates via the ACME protocol, and Certbot is the recommended ACME client that handles […]

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How to Configure Network Interface Settings with nmcli and ip on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Configure Network Interface Settings with nmcli and ip on RHEL 9

Network configuration on RHEL 9 is managed by NetworkManager, and the primary tools for working with it are nmcli (NetworkManager Command-Line Interface) and the traditional ip command from the iproute2 package. Understanding both is essential: nmcli creates persistent network profiles that survive reboots and are managed by NetworkManager, while the ip command makes temporary changes […]

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How to Schedule Automated Tasks with cron and anacron on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Schedule Automated Tasks with cron and anacron on RHEL 9

Automated task scheduling is the backbone of server maintenance: backups run at 3 AM, log cleanup happens daily, SSL certificates renew before they expire, and databases are vacuumed weekly. On RHEL 9, there are three scheduling mechanisms each suited to different scenarios. cron is the classic daemon that runs jobs on a schedule defined by […]

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How to Configure /etc/hosts, /etc/resolv.conf and DNS Resolution on RHEL 9 — step-by-step RHEL 9 tutorial on Progressive Robot

How to Configure /etc/hosts, /etc/resolv.conf and DNS Resolution on RHEL 9

DNS resolution on a Linux server is a multi-layered system. When an application calls getaddrinfo(“example.com”), the request passes through the Name Service Switch (NSS) framework, which consults sources in the order defined in /etc/nsswitch.conf — typically /etc/hosts first, then a DNS resolver. The DNS resolver reads its configuration from /etc/resolv.conf, which lists the DNS servers […]

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