Articles

Explanations, step-by-step guides, cheat sheets and fixes. Pick an area, or tell us what you need.

42 entries match these filters

0454 Scan your own code and containers in CI: Gitleaks, Semgrep and Trivy Set up a GitHub Actions workflow that runs Gitleaks, Semgrep and Trivy on every push of your own project, learn what each… Intermediate · Step by step · Any system Article Pipelines, runners & hooks · Security testing & CTF 15 Oct 2026
0432 Try Sigma rules against your own logs Install the sigma-cli converter, take a rule from the public SigmaHQ library, convert it into a query for a log tool you… Intermediate · Step by step · Linux, macOS Article Logs · Security resources & detection 15 Oct 2026
0409 Nginx as a reverse proxy with HTTPS Put Nginx in front of an app on localhost: a server block that proxies to the port, forwards the client headers, supports… Intermediate · Step by step · Linux Article Deploying sites · Web servers & reverse proxies 15 Oct 2026
0411 CORS explained, and how to fix the browser error The browser blocks a request from one origin to another unless the server allows it with Access-Control headers. Fix it in the… Intermediate · Step by step · Any system, Browser Article Making requests · Web servers & reverse proxies 15 Oct 2026
0422 Dotfiles: keep your shell setup in git Put .bashrc, .zshrc, .gitconfig and your editor settings into a git repository so a new machine is set up in minutes: a… Intermediate · Step by step · Linux, macOS Article Modern command-line tools · Setup 15 Oct 2026
0373 Loki: ship and search logs Run Loki, Grafana Alloy and Grafana with Docker Compose, collect the systemd journal and /var/log files with a short Alloy configuration, and… Intermediate · Step by step · Linux Article Logs 15 Oct 2026
0364 Schedule PostgreSQL and MySQL dumps with systemd timers Write one dump script for PostgreSQL and MySQL, run it from a systemd service and timer instead of cron, keep two weeks… Intermediate · Step by step · Linux Article Backup tools · PostgreSQL 15 Oct 2026
0365 Proxmox Backup Server: first setup and first restore Install Proxmox Backup Server, create a datastore and a backup user, connect it to Proxmox VE as storage, run the first VM… Intermediate · Step by step · Linux Article Backup & restore · Backup tools 15 Oct 2026
0353 fail2ban: block repeated failed logins Install fail2ban, enable the sshd jail with sane ban times, whitelist your own address, read the ban list, unban someone, and add… Intermediate · Step by step · Linux Article Server hardening · SSH 15 Oct 2026
0354 sudo rules: give a user exactly the rights they need Write sudoers rules with visudo: full admin for operators, a short list of commands for a deploy account, no-password rules for automation,… Intermediate · Step by step · Linux Article Secrets & access · Users, sudo & hardening 15 Oct 2026
0363 Restore drill: prove your backup works in 15 minutes A repeatable procedure to restore one file and one database from your newest backup into a scratch location, compare the result with… Intermediate · Step by step · Linux, macOS Article Backup tools · Strategy & restore drills 15 Oct 2026
0330 Write a Dockerfile: FROM, COPY, RUN, CMD and multi-stage builds How a Dockerfile turns into an image layer by layer, what the main instructions do, how to order them for fast rebuilds,… Intermediate · Step by step · Linux, macOS, Windows Article Docker basics · Images & registries 15 Oct 2026
0331 docker compose for an app with a PostgreSQL database A compose.yaml that runs your application next to a PostgreSQL container, with a named volume for the data, a health check so… Intermediate · Step by step · Linux, macOS, Windows Article Docker Compose · Install & connect 15 Oct 2026
0332 Tag, push and pull images with Docker Hub and other registries How image names map to registries, how to log in, tag and push an image to Docker Hub, GitHub Container Registry or… Intermediate · Step by step · Linux, macOS, Windows Article Images & registries 15 Oct 2026
0233 Turn on MongoDB authentication and create least-privilege users A fresh MongoDB install accepts connections without a password. Create a user administrator, enable authorization, then give each application and backup job… Intermediate · Step by step · Linux Article Administration · Security & access 15 Oct 2026
0243 Database backup strategy: the 3-2-1 rule and testing restores Keep three copies of your data on two kinds of storage with one copy offsite, choose dump or snapshot methods per database,… Intermediate · Step by step · Linux Article Database operations · Security & access 15 Oct 2026
0225 Oracle Data Pump: export and import schemas with expdp and impdp Data Pump moves schemas, tables or whole databases between Oracle databases as dump files. Set up a directory object, export with expdp… Intermediate · Step by step · Linux, Windows Article Administration · Backup with RMAN 15 Oct 2026
0169 Add a new disk: partition, format and mount it by UUID Find a new disk with lsblk, partition it with parted, create an ext4 or XFS filesystem and mount it permanently through /etc/fstab… Intermediate · Step by step · Linux Article Disks, LVM & filesystems 15 Oct 2026
0173 Set a static IP address: nmcli on RHEL vs netplan on Ubuntu RHEL, Rocky and AlmaLinux configure networking with NetworkManager (nmcli); Ubuntu Server uses netplan YAML. Here is the same static IP setup in… Intermediate · Step by step · Linux Article Networking & firewalls 15 Oct 2026
0175 Open ports with firewalld and ufw firewalld (RHEL, Rocky, AlmaLinux) and ufw (Ubuntu) are friendly front ends to the kernel firewall. Allow SSH first, then open only the… Intermediate · Step by step · Linux Article Networking & firewalls 15 Oct 2026
0192 Grafana basics: connect Prometheus, build a dashboard and set up an alert Connect Grafana to Prometheus, build a dashboard for your servers with PromQL panels and a host selector, and create an alert rule… Intermediate · Step by step · Linux Article Prometheus & Grafana 15 Oct 2026
0200 PostgreSQL roles, privileges and default privileges Create login and group roles, grant access to databases, schemas and tables, and use ALTER DEFAULT PRIVILEGES so tables created later get… Intermediate · Step by step · Linux Article Roles & administration · Security & access 15 Oct 2026
0165 Write a systemd service unit for your own app Turn any long-running program into a proper service: create a unit file, run it as an unprivileged user, restart it on failure… Intermediate · Step by step · Linux Article Services & systemd 15 Oct 2026
0166 Replace a cron job with a systemd timer A systemd timer runs a service on a schedule like cron, but logs every run to the journal, can catch up missed… Intermediate · Step by step · Linux Article Services & systemd 15 Oct 2026
0136 Persistent storage in Kubernetes: PersistentVolumes, claims and StorageClasses How to give a Pod storage that survives restarts: request it with a PersistentVolumeClaim, let a StorageClass provision it, and mount it.… Intermediate · Step by step · Linux Article Config, secrets & storage · Workloads & services 15 Oct 2026
0137 Helm basics: install a chart, override values, upgrade and roll back Helm installs packaged Kubernetes apps called charts. Learn to add a repository, install a release, customize it with values files, upgrade it… Intermediate · Step by step · Any system Article Helm 15 Oct 2026
0152 Build and deploy from source with oc new-app and Source-to-Image How oc new-app turns a Git repository or an image into a running app, how Source-to-Image and Docker builds are chosen, and… Intermediate · Step by step · Any system Article Deploying applications 15 Oct 2026
0153 Expose apps with OpenShift Routes: edge, passthrough and re-encrypt TLS A Route publishes a service on a host name through the OpenShift router. Learn when to use plain HTTP, edge, passthrough or… Intermediate · Step by step · Any system Article Deploying applications · Ingress & networking 15 Oct 2026
0154 OpenShift app configuration: environment, ConfigMaps, Secrets and persistent storage Set environment variables, load ConfigMaps and Secrets into a Deployment as variables or files, and give it persistent storage with a PersistentVolumeClaim,… Intermediate · Step by step · Any system Article Config, secrets & storage · Deploying applications 15 Oct 2026
0103 Proxmox VE networking: Linux bridges (vmbr0) and VLANs Guests reach the network through Linux bridges such as vmbr0, defined in /etc/network/interfaces. Learn the default setup, VLAN-aware bridges, VLAN tags for… Intermediate · Step by step · Linux Article Installation & first steps · Networking & firewalls 15 Oct 2026
0106 Back up and restore guests with vzdump, backup jobs and Proxmox Backup Server Back up Proxmox VE VMs and containers with vzdump, choose a backup mode, schedule backup jobs with retention, restore with qmrestore or… Intermediate · Step by step · Linux Article Backup & restore 15 Oct 2026
0117 Configure the OCI CLI for Oracle Private Cloud Appliance 3.x Point the standard OCI CLI at a PCA 3.x Compute Enclave: create an API key, write ~/.oci/config with the appliance as the… Intermediate · Step by step · Any system Article Compute, networking & storage 15 Oct 2026
0118 Create a compute instance on PCA 3.x with the Compute Web UI or OCI CLI Launch a VM in the Private Cloud Appliance 3.x Compute Enclave: gather an image, shape, subnet and SSH key, then create the… Intermediate · Step by step · Any system Article Compute, networking & storage 15 Oct 2026
0119 PCA 3.x networking basics: create a VCN, subnets and security lists On Private Cloud Appliance 3.x, instances need a VCN and a subnet. Create them in the Compute Web UI or OCI CLI… Intermediate · Step by step · Any system Article Compute, networking & storage 15 Oct 2026
0120 Block volumes on PCA 3.x: create, attach and mount a data disk Add storage to a Private Cloud Appliance 3.x instance: create a block volume, attach it as paravirtualized, then format and mount it… Intermediate · Step by step · Any system Article Compute, networking & storage 15 Oct 2026
0125 Create a KVM virtual machine with virt-install Use virt-install to create libvirt/KVM guests: install from an ISO, run a text-only install over the serial console, or import a cloud… Intermediate · Step by step · Linux Article Basics 15 Oct 2026
0074 pandas basics: read a CSV, filter rows and summarize with groupby Load a CSV into a pandas DataFrame, inspect it, filter rows with conditions, and compute totals per group, with the SQL equivalent… Intermediate · Step by step · Any system Article Data analysis · Files & automation 15 Oct 2026
0100 Create a VM and a cloud-init template with qm Create KVM virtual machines from the command line with qm, then build a reusable cloud-init template from a cloud image and clone… Intermediate · Step by step · Linux Article Basics · VMs & containers 15 Oct 2026
0052 Slice and summarize text with grep, sort, uniq, cut, awk and sed A handful of classic tools can filter, count, extract and rewrite text right in the terminal. This guide shows the patterns you… Intermediate · Step by step · Linux, macOS Article Finding files & text · Text processing 15 Oct 2026
0056 Docker Compose: run a small web app with a database Docker Compose describes several containers, their ports, volumes and environment in one compose.yaml file, then starts them all with docker compose up. Intermediate · Step by step · Linux, macOS, Windows Article Docker basics · Docker Compose 15 Oct 2026