Linux Server Admin with Fexingo: Sysadmin, Bash, and Server Engineering

In this episode of Linux Server Admin, Lucas and Luna dig into the practical side of backup strategy for Linux servers. They break down the 3-2-1 rule, compare full, incremental, and differential backups, and walk through a real-world scenario using rsync and a LUKS-encrypted external drive. They also discuss testing restores, common pitfalls like silent corruption and backup drift, and share a qu...

Episode 146 of Linux Server Admin dives into SSH jump hosts, a practical way to secure multi-server environments. Lucas and Luna walk through the setup of a bastion host, showing how to use ProxyJump to route connections safely, along with key-based authentication and agent forwarding done right. They ground the discussion in a real-world scenario of managing a small fleet of servers, and they sha...

In this episode of Linux Server Admin, Lucas and Luna explore the power of auditd, the Linux audit daemon, for tracking security-relevant events on your servers. They walk through a practical setup for monitoring file access and user commands, explaining how audit rules work, how to interpret audit logs, and how to use ausearch and aureport to make sense of the data. They also discuss performance...

In this episode of Linux Server Admin, Lucas and Luna dive into the often-overlooked world of I/O schedulers on modern NVMe drives. With the rise of NVMe storage, traditional schedulers like CFQ and even deadline are becoming less relevant, and the choice between none, mq-deadline, and bfq can have a real impact on latency and throughput. Lucas shares a production story from a busy PostgreSQL serv...

In this episode of Linux Server Admin, Lucas and Luna dive into the practical differences between cron and systemd timer units for scheduling jobs on modern Linux servers. They explore why timers offer better logging, dependency handling, and reliability, using a real-world scenario of a backup job that failed silently under cron. The discussion covers how to configure a simple timer unit, trigger...

In this episode, Lucas and Luna dive into the practical use of Linux namespaces for process isolation, going beyond the usual container talk. They focus on the mount namespace and how it can prevent a runaway process from clobbering your server's filesystem. You'll hear how a simple unshare command can give you a sandboxed view of the filesystem, and why pivot_root is the missing piece for truly i...

In this episode of Linux Server Admin, Lucas and Luna dive into disk quotas on Linux servers, focusing on XFS quota management. They explain the difference between user and project quotas, how to set up quota accounting on XFS, and practical tools like xfs_quota and quotaon. They also discuss common pitfalls like inode limits, journaled quotas, and how to avoid performance hits. Perfect for sysadm...

In this episode of Linux Server Admin, Lucas and Luna dive into the often-overlooked but critical task of keeping server clocks accurate using Chrony. They walk through real-world failures caused by time drift — from authentication errors to broken log sequencing — and explain how Chrony addresses the shortcomings of older NTP implementations. You'll learn basic configuration with pool and iburst...

Episode 139 dives into LVM thin provisioning on Linux servers — a storage strategy that lets you over-commit disk capacity without wasting physical space. Lucas walks through creating a thin pool, provisioning logical volumes, enabling auto-extension, and leveraging snapshots for fast dev/test rollbacks. Luna challenges the trade-off: what happens when the pool fills up? They also cover monitoring...

User namespaces are a powerful Linux kernel feature that lets containers run as ‘root’ inside their namespace while actually running as an unprivileged user on the host. In this episode, Lucas and Luna walk through a real-world scenario: an attacker who compromises a containerized web app and tries to escape to the host. With user namespace mapping, the attacker’s root privileges inside the contai...

In this episode, Lucas walks through setting up Prometheus version 2.53 and Node Exporter on a freshly provisioned Ubuntu 24.04 server. He demonstrates how to install the binaries from the official tarball, configure the prometheus.yml to scrape localhost:9100 every 15 seconds, and verify metric ingestion using the expression browser. Luna asks about the pull model versus push-based tools, and Luc...

When your Linux web server stalls for five seconds on every other request, where do you start? This episode walks through a real debugging session using strace and ltrace to uncover a hidden file-lock bottleneck. Lucas and Luna trace system calls and library calls in real time, showing how a single read operation on a shared config file turned a fast Nginx server into a crawl. You'll learn the pra...

In this episode of Linux Server Admin, Lucas and Luna walk through the practical steps of encrypting a server's disk using LUKS (Linux Unified Key Setup). They cover partitioning an encrypted LVM volume, creating a LUKS container, unlocking it at boot via a keyfile stored on an initramfs, and managing passphrases. The discussion includes performance considerations, backup of LUKS headers, and inte...

Episode 134 digs into SELinux — the mandatory access control layer most sysadmins avoid. Lucas and Luna break down how SELinux works, why it matters for application confinement, and walk through a real example: locking down an Apache web server with targeted policies. They cover booleans, contexts, and audit logs, plus common pitfalls like confined vs unconfined domains. If you've never touched SE...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into the art of swap configuration on modern Linux servers. They debunk the old 'twice the RAM' rule, explain why SSDs change the calculus, and walk through practical adjustments like setting vm.swappiness to 10 for database workloads. The conversation also covers compressed swap options like zram and zswap, and how to monitor...

Episode 132 of Linux Server Admin tackles systemd service hardening. Lucas and Luna break down a real-world case: a misconfigured Apache server that exposed /etc/shadow due to missing sandboxing. They walk through systemd's security directives—PrivateTmp, ProtectSystem, NoNewPrivileges, and more—and discuss common pitfalls like breaking legitimate functionality. Practical tips for locking down ser...

In this episode of Linux Server Admin, Lucas and Luna dive into cgroups v2, the modern kernel feature for limiting CPU and memory usage of processes. They explain why traditional tools like nice and ulimit fall short, and demonstrate how to use systemd's drop-in files to apply resource constraints to any service. Using a real-world example of a memory-hungry database process, they show how to set...

Lucas and Luna dive into perf, the Linux profiling tool, with a real production scenario: a web server experiencing high CPU latency. They walk through capturing performance data using perf record, analyzing hot functions with perf report, and visualizing call stacks with flamegraphs. You'll learn how to pinpoint the exact function consuming CPU cycles—whether it's a Lua script in Nginx or a kerne...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into practical log aggregation using systemd-journald, the built-in logging daemon on modern Linux servers. They explain how to centralize logs from multiple services, filter by priority, use journald's structured metadata, and forward logs to a remote syslog server for centralized monitoring. The discussion covers real scenar...

Lucas and Luna dive into the tuned daemon, a Linux tool that dynamically adjusts kernel parameters, CPU governor, disk elevator, and network settings based on workload profiles. They walk through how to install tuned on Ubuntu 24.04, inspect active profiles with tuned-adm, and explain the difference between throughput-performance and latency-performance profiles. Lucas shares a real-world example...

Episode 127 of Linux Server Admin with Fexingo dives into Kernel Same-page Merging (KSM) – a Linux kernel feature that deduplicates identical memory pages to reduce RAM usage in virtualized and containerized environments. Lucas and Luna walk through how KSM works under the hood, from the memory scan daemon to the merge_across_nodes and sleep_millisecs tuning knobs. They discuss real-world use case...

In this episode, Lucas and Luna dive into Linux network namespaces (netns) — a lightweight way to create isolated network stacks on a single host without full virtualization. They walk through setting up a test environment with two network namespaces connected by a virtual Ethernet pair, demonstrating how to run services in isolation for development, security testing, or multi-tenant workloads. Lu...

Episode 125 of Linux Server Admin with Fexingo dives into SSH certificate authority (SSH CA) as a modern alternative to managing thousands of authorized_keys files. Lucas and Luna walk through the practical setup: creating a CA key pair, signing host and user certificates, and configuring sshd to trust the CA. They discuss why Netflix and other large orgs adopted SSH CA to eliminate key sprawl and...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into Linux server network bonding—combining multiple physical network interfaces into a single logical link for redundancy and increased throughput. They walk through the seven bonding modes defined in the Linux kernel, focusing on the most practical ones: active-backup for failover, balance-xor and 802.3ad (LACP) for load bal...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into TCP BBR congestion control—a Google-developed algorithm that can dramatically boost network throughput and reduce latency. They explain how BBR works at a high level, compare it to traditional algorithms like CUBIC, and walk through the practical steps to enable it on a Linux server: checking the kernel version, loading t...