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

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into Linux kernel module management using modprobe. They explore how to load, unload, and configure kernel modules dynamically, without rebooting. The discussion covers real-world scenarios like adding hardware support for a new NIC on a production server, using modprobe.d configuration files for persistent settings, and troub...

In Episode 121 of Linux Server Admin, Lucas and Luna dive into auto-scaling Linux servers using systemd timers and path triggers. They walk through a real scenario: a background worker pool that scales up when a queue directory hits 100 files and scales down after idle time — all without external orchestration tools. Lucas explains how to write systemd service templates with `%i` instancing, pair...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into the concept of break glass procedures for emergency server access. They explore a real-world scenario where a critical service goes down and the primary admin is unreachable, discussing how to set up time-limited, audited access paths using tools like systemd timers, SSH key rotation, and sudo rules. The hosts cover a con...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into AIDE (Advanced Intrusion Detection Environment) for monitoring config file drift on Linux servers. They walk through a real example: a misconfigured Apache virtual host that went unnoticed for weeks after a junior admin changed a DocumentRoot path without updating the change log. Lucas explains how AIDE builds a baseline...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into Linux server I/O scheduling — a critical but often overlooked performance lever. They break down the three main schedulers in the modern kernel — mq-deadline, kyber, and BFQ — and explain when to use each one based on your workload. Lucas shares a real-world example: tuning a database server's NVMe drives from the default...

In this episode, Lucas and Luna dive into automated security patching for Linux servers using the unattended-upgrades package. They discuss why many sysadmins fear automatic updates, how to configure unattended-upgrades safely for production environments, and the real-world experience of a company that reduced their patch window from two weeks to under four hours without a single outage. Lucas exp...

In this episode of Linux Server Admin, Lucas and Luna dive into the practical art of network troubleshooting using two often-overlooked command-line tools: tracepath and MTR (My TraceRoute). They explain how tracepath provides a quick, no-frills path discovery without requiring root privileges, while MTR combines the best of traceroute and ping in real time, giving system administrators a powerful...

In episode 115, Lucas and Luna break down the practical decisions behind RAID configuration on Linux servers. They walk through the trade-offs between hardware and software RAID, explain when mdadm still beats modern alternatives, and share a real-world story about a misconfigured RAID 5 array that cost a startup two days of downtime. The episode covers stripe size selection, the case for RAID 10...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into securing NFSv4 with Kerberos authentication. They walk through the practical steps of configuring a Kerberos Key Distribution Center (KDC) on CentOS Stream, setting up NFSv4 with RPCSEC_GSS, and debugging common issues like keytab mismatches and time sync problems. By the end, you'll understand how to replace insecure AUT...

In this episode, Lucas and Luna dive into Linux server storage tiering using LVM cache, a technique that combines fast SSDs with slower HDDs to create a hybrid volume. They explain how LVM cache works on a block level, using the 'cache' target in device-mapper to promote frequently accessed blocks to the fast tier. Lucas walks through a concrete example: setting up a cache pool with an NVMe drive...

In this episode, Lucas and Luna dive into Intel QuickAssist Technology (QAT) for Linux servers—a hardware accelerator that offloads cryptographic operations like TLS handshakes and IPsec encryption from the CPU. They walk through how QAT works at the kernel driver level, how it integrates with OpenSSL via the async engine, and real-world performance gains: up to 50% lower latency for TLS and 4x th...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into setting up a Samba-based Active Directory Domain Controller on a Linux server. They cover the key differences between Samba 4 and classic NT4-style domains, walk through the necessary packages and configuration steps for joining a domain, and discuss real-world use cases like centralized authentication and group policy ma...

Ever had a production application fail silently with 'permission denied' and spent hours chasing ghosts? Lucas and Luna break down strace, the Linux system call tracer that saved one sysadmin's weekend after a custom daemon crashed on startup. They walk through a real example: tracing execve, open, and connect syscalls to spot missing file descriptors and misconfigured seccomp filters. You'll lear...

Episode 109 of Linux Server Admin with Fexingo dives into a powerful but often overlooked systemd feature: OnFailure=, which automatically triggers a rescue unit when a critical service fails. Lucas and Luna walk through a real-world scenario — a database server that needs to page the admin and attempt a safe restart without manual intervention. They cover how to pair OnFailure with a custom targe...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into Linux server disk quota management using the classic quota tools. They walk through setting up quotas on an ext4 filesystem, covering user and group quotas, grace periods, and the soft/hard limit distinction. Using a real example of a shared development server with 20 users, they explain how to enable quotas at the filesy...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into the systemd journal (journalctl) as a centralized logging solution for Linux servers. They explain how journald collects structured logs from the kernel, services, and applications, and compare it to traditional syslog. Lucas demonstrates practical commands for filtering logs by service, priority, time range, and boot ses...

Lucas and Luna dive into Linux Logical Volume Manager (LVM) snapshots—a powerful tool for creating point-in-time copies of filesystems. They explain how snapshots work using copy-on-write, walk through a practical example of backing up a MySQL database with a 10-gigabyte logical volume, and discuss common pitfalls like snapshot exhaustion. By the end, you'll know how to create, mount, and remove L...

In this episode, Lucas and Luna dive into the BPF Compiler Collection (BCC) for Linux server performance analysis. They explore how BCC provides dynamic tracing tools for understanding system behavior without recompiling kernels. Using a concrete example of diagnosing a database slowdown on a production server, Lucas explains how to use the 'biolatency' and 'runqlat' tools to pinpoint issues. Luna...

Lucas and Luna dive into Linux namespace isolation using the 'unshare' command. They explain how unshare allows you to create isolated environments for processes without needing full container runtimes. Using a concrete example, they walk through creating a namespace with its own mount table, process tree, and network stack, showing how it differs from tools like Docker and LXC. They discuss use c...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into etckeeper, a lightweight tool that automatically version-controls your /etc directory with Git. They walk through installation, configuration, and a real-world scenario where etckeeper saved a sysadmin after a botched Nginx config edit. You'll learn how to set it up in under five minutes, how it integrates with package ma...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into network performance tuning on Linux servers using the sysctl utility. They focus on a practical case: optimizing TCP stack parameters for a high-traffic web server handling thousands of concurrent connections. Lucas explains how to adjust settings like net.core.somaxconn, net.ipv4.tcp_tw_reuse, and net.ipv4.tcp_fin_timeou...

In this episode of Linux Server Admin with Fexingo, Lucas and Luna dive into network bonding for Linux servers using the modern teamd daemon. They explain how to combine multiple physical NICs into a single logical interface for redundancy and increased throughput, covering active-backup and load-balancing modes. The hosts walk through a practical example of configuring a two-NIC bond on a CentOS...

Episode 100 of Linux Server Admin with Fexingo: Lucas and Luna dive into performance tuning with Tuned, the Linux systemd service that applies predefined profiles to optimize server workloads. They break down the difference between virtual-guest, throughput-performance, and latency-performance profiles using a real-world example of a PostgreSQL database server struggling with background batch jobs...

In episode 99 of Linux Server Admin with Fexingo, Lucas and Luna dive into Linux control groups (cgroups) version 2, a powerful kernel feature for limiting, accounting, and isolating CPU, memory, and I/O usage of processes. They walk through a concrete example: setting up a memory limit on a web server process to prevent an out-of-control PHP-FPM pool from crashing the whole machine. Along the way...

In episode 98 of Linux Server Admin with Fexingo, Lucas and Luna dive into the world of FUSE — Filesystem in Userspace. They explain how FUSE lets you build custom file systems without kernel modules, walk through a real example of mounting an S3 bucket as a local directory using s3fs-fuse, discuss performance trade-offs (context-switch overhead vs. development speed), and share practical tips for...