The Linux kernel exposes hundreds of tunable parameters through the /proc/sys virtual filesystem, and sysctl is the tool used to read and write these values persistently. Many default kernel settings prioritize compatibility and functionality over security, leaving attack surface that can be closed with targeted configuration. On RHEL 8, persistent sysctl settings are stored in […]
tmux is a terminal multiplexer that lets you run multiple shell sessions inside a single terminal window, keep sessions alive after you disconnect from SSH, and split your screen into panes for simultaneous work. On RHEL 8 it is available from the default AppStream repository and requires no additional configuration to get started. This tutorial […]
A Linux network bridge acts like a virtual switch, forwarding frames between connected interfaces at Layer 2. Bridges are essential when running virtual machines with QEMU/KVM or containers (Podman/Docker) that need full network access on the same subnet as the host. On RHEL 8, NetworkManager is the authoritative networking service, and nmcli is the recommended […]
How to Use Terraform to Provision Infrastructure on RHEL 7 Once Terraform is installed, the real power comes from writing complete, production-grade infrastructure configurations. A single Terraform project can define an entire cloud environment — VPC networking, subnets, security groups, EC2 instances, load balancers, and databases — all in version-controlled code that can be reviewed, […]
GNU Make is one of the oldest and most reliable build automation tools in software development, yet it remains deeply relevant in modern DevOps workflows. A Makefile acts as a self-documenting command runner that codifies every build, test, lint, and deploy action in a single file that any developer or CI system can invoke with […]
PostgreSQL streaming replication continuously ships Write-Ahead Log (WAL) records from a primary server to one or more standby replicas in near real time. The standby can serve as a warm failover target or, in hot-standby mode, accept read-only queries to offload reporting traffic from the primary. This tutorial configures a two-node streaming replication setup on […]
How to Configure SELinux on RHEL 7 SELinux (Security-Enhanced Linux) is a mandatory access control (MAC) system built into the Linux kernel and enabled by default on every RHEL 7 installation. Unlike traditional Unix discretionary access control (DAC), which lets file owners decide who can access their files, SELinux enforces a policy defined by the […]
Port knocking is a stealthy technique that keeps SSH’s port 22 invisible to network scanners until a client sends a precise sequence of connection attempts to predetermined ports. On RHEL 8, combining knockd with firewalld creates a powerful two-layer defense: the firewall silently drops all traffic on port 22 by default, and only the knock […]
How to Use Makefile for Build Automation on RHEL 7 The Makefile has been a cornerstone of software build automation since the 1970s, and it remains one of the most versatile and universally available tools on any Linux system. On RHEL 7, GNU Make is installed by default as part of the base system or […]
How to Configure Automatic Security Updates on RHEL 7 Keeping a RHEL 7 server patched against known vulnerabilities is one of the most impactful things you can do to improve its security posture. While manual patching is reliable, it requires discipline and can be delayed during busy operational periods. Automating security updates ensures that critical […]
