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

Episode 47 of Linux Server Admin with Fexingo dives into cgroups v2, the modern control group implementation that replaces the fragmented v1 system. Lucas and Luna walk through real server scenarios: limiting CPU shares for noisy neighbors on a shared web host, pinning memory for a critical database container, and configuring IO throttling for backup jobs. They explain how systemd integrates cgrou...

In this episode of Linux Server Admin, Lucas and Luna tackle the often overlooked tuning of NFS (Network File System) on Linux servers. Using a real-world case of a media rendering farm struggling with NFS latency, they walk through the key sysctl settings, mount options, and server-side daemon parameters that can dramatically improve throughput. You'll learn about the `rsize` and `wsize` mount op...

Episode 45 of Linux Server Admin with Fexingo dives into Stratis, a Linux storage management tool that combines ZFS-like features with native kernel integration. Lucas and Luna explain how Stratis uses a pool-based model, thin provisioning, snapshots, and tiering without the complexity of traditional volume managers. They walk through installing Stratis on RHEL 9, creating a pool from two NVMe dri...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into the practical art of iptables on Linux. They start with a real-world scenario: a misconfigured firewall that locked out a developer's SSH session. From there, they explore three specific iptables use cases that go beyond basic port blocking—rate-limiting inbound connections to prevent brute-force attacks, using connection...

In this episode, Lucas and Luna dive into logrotate, the unsung hero of Linux server administration. They explore how a single misconfigured logrotate rule can silently fill a disk partition, causing outages. Using a concrete example of a web server that crashed because Apache logs grew unchecked, they explain logrotate's core directives: daily rotation, compression, delay compress, maxage, and po...

Episode 42 of Linux Server Admin with Fexingo dives into diagnosing and fixing packet loss on Linux servers. Lucas and Luna explore practical tools like ping, mtr, tcpdump, and ethtool to pinpoint whether the issue is in the network interface, cable, switch, or kernel buffers. They walk through a real-world scenario where a jammed network cable on a Ubuntu server caused 2.3% packet loss, and show...

Memory leaks on Linux servers can silently degrade performance until a process is killed or the system crashes. In this episode, Lucas and Luna walk through a real-world scenario: a Node.js web server that slowly consumes memory over days. They explain how to use tools like 'top', 'ps', '/proc/meminfo', 'smem', and 'valgrind' to identify the offending process, measure memory growth, and trace the...

In this episode of Linux Server Admin, Lucas and Luna dive into systemd timers as a modern replacement for cron. They walk through the anatomy of a timer unit file, compare it to traditional cron syntax, and show you how to create your first timer for a daily log rotation script. Lucas explains why systemd timers offer better logging, dependency handling, and debugging capabilities. They also disc...

Episode 39 of Linux Server Admin dives into Linux network namespaces for isolating server processes without full container runtimes. Lucas and Luna break down a real scenario: running a legacy monitoring agent that can't be containerized but must be network-separated from production traffic. They walk through creating a namespace, assigning a virtual Ethernet pair, and routing traffic through a de...

Lucas and Luna dive into Linux auditd, the powerful auditing subsystem that tracks security-relevant events on your servers. They walk through a real-world scenario: detecting unauthorized file access attempts using auditctl rules, interpreting ausearch output, and generating daily reports with aureport. The episode covers how to configure auditd without overwhelming your logs, common pitfalls lik...

Episode 37 of Linux Server Admin with Fexingo dives into control groups (cgroups) — the kernel feature that lets you limit CPU, memory, and I/O per process. Lucas and Luna walk through a real scenario: a runaway PHP-FPM pool consuming all server RAM on a shared hosting box. They explain how to set memory and CPU limits with cgroups v2, how to monitor usage with systemd-cgtop, and why this beats tr...

Episode 36 of Linux Server Admin with Fexingo dives into disk I/O benchmarking with FIO. Lucas and Luna walk through a real-world scenario: a database server showing intermittent slow queries, traced to unexpected I/O latency. They explain how to install FIO, construct a basic random-read/write test, interpret the output (IOPS, latency percentiles, bandwidth), and compare against expected performa...

Episode 35 tackles the hidden risk of inconsistent patching on Linux servers. Lucas and Luna walk through a real-world case: a mid-sized e-commerce company that suffered a 12-hour outage after applying kernel patches manually on a Friday afternoon. They break down why most sysadmins still rely on ad-hoc updates, how unattended-upgrades can backfire, and what a structured patch window looks like —...

Episode 34 of Linux Server Admin with Fexingo. Lucas and Luna walk through a real-world DNS failure that took down a staging environment for six hours. They explain how to use `dig`, `nslookup`, `systemd-resolved`, and `/etc/nsswitch.conf` to pinpoint the cause, and share a concrete fix using conditional forwarding in `systemd-resolved`. You'll also learn how to monitor DNS health with a simple cu...

Lucas and Luna dive into Linux namespaces, the kernel feature that underpins container isolation but is often misunderstood. They explain the seven namespace types, show how a misconfigured namespace can leak host resources, and walk through a practical example using 'unshare' to create a minimal container. The hosts also discuss auditing namespace configurations with 'lsns' and 'nsenter', and why...

When your Linux server kernel panics, the typical sysadmin response is a hard reset — but that can destroy forensic evidence and risk data corruption. In this episode, Lucas and Luna walk through a step-by-step recovery procedure using the kernel's built-in SysRq key mechanism, the kdump crash-capture service, and crash utility analysis. They explain how to configure kdump to save a vmcore file on...

Episode 31 of Linux Server Admin with Fexingo dives into the nightmare scenario: your Linux server's root filesystem is corrupted and won't boot. Lucas and Luna walk through a real rescue using the initramfs shell, manual fsck on a read-only root, chroot into the damaged system, and rebuilding the initramfs from inside the rescue environment. They cover when to use a live USB, how to mount proc/sy...

Episode 30 of Linux Server Admin with Fexingo tackles one of the most insidious server problems: a disk that's technically online but corrupting data silently. Lucas and Luna walk through a real case from a mid-size e-commerce company where a failing SATA drive went unnoticed for weeks, causing intermittent database corruption and mysterious application crashes. They explain how to detect the earl...

Episode 29 of Linux Server Admin with Fexingo dives into the hidden bottleneck in systemd's journald: the default rate-limiting settings that silently drop log entries during bursts, making debugging impossible when you need logs most. Lucas and Luna walk through a real scenario where a busy web server was losing critical audit records because journald capped the rate at 10,000 messages per 30 sec...

In this episode of Linux Server Admin, Lucas and Luna dive into AppArmor—the mandatory access control system that's simpler than SELinux but powerful enough to confine major services like Nginx, MySQL, and Apache. They walk through a real-world case: a misbehaving PHP script that tried to write to /etc/passwd on a production web server, and how an AppArmor profile blocked it instantly. Lucas expla...

Lucas and Luna dive into a practical server engineering headache: timeouts. Lucas explains why the default systemd service timeout of 90 seconds can cause cascading failures in production, especially for long-running database migrations or backup jobs. He walks through creating drop-in units to override timeout settings without touching vendor-provided service files, using a real case from a Postg...

In this episode, Lucas and Luna dive into SELinux on Linux servers — specifically, why and how to implement targeted policies without breaking production workloads. Lucas walks through a real case from a financial services company that reduced their kernel-level vulnerability exposure by over 80 percent after enabling SELinux in enforcing mode on 200 servers. They discuss the common pain points: l...

Episode 25 of Linux Server Admin with Fexingo: Sysadmin, Bash, and Server Engineering dives into SSH key hygiene. Lucas and Luna walk through a real-world scenario: a startup that accumulated 400 authorized SSH keys across 60 servers, with keys tied to former employees and contractors still active. They explain why this happens, how to inventory keys using simple Bash scripts and tools like ssh-au...

Episode 24 of Linux Server Admin with Fexingo digs into a critical but often overlooked security gap: the sudoers file. Lucas and Luna walk through a real-world misconfiguration that gave an attacker passwordless root access on a monitoring server, and explain how to lock down sudo with defaults, timed credentials, command aliases, and the sudo_logsrvd audit daemon. They cover the new sudo 1.9.14...

Episode 23 of Linux Server Admin with Fexingo. Lucas and Luna dig into one of the most common yet misunderstood server failure modes: swap thrashing. They walk through a real scenario where a Postgres query triggered the OOM killer, and explain why the default vm.swappiness of 60 is almost always wrong for production. You'll learn exactly how to set swappiness to 10, configure systemd-oomd, and ad...