Guides and tutorials for Linux system administration
Most Linux services ship with the same trust level as root. systemd has had per-unit security directives for years; almost nobody uses them. Here is the unit-file pattern that survives a security review....
The ARP table maps IP addresses to MAC addresses. Monitoring it helps detect MAC spoofing, duplicate IPs, and rogue devices on your network....
Disk I/O bottlenecks cause slow applications and database timeouts. Learn to measure IOPS, throughput, and latency using /proc/diskstats and standard Linux tools....
Load average is the most misunderstood Linux metric. Learn what 1/5/15 minute load means relative to CPU count, how to identify bottlenecks, and when to worry....
Core dumps consume disk space and may contain sensitive data. Learn to detect, analyze, and manage core dumps with coredumpctl and kernel settings....
Systemd journald centralizes all system logs. Learn to analyze journal statistics, export logs by priority and unit, and manage journal disk usage effectively....
Hostname misconfigurations cause SSL certificate issues, email delivery failures, and service discovery problems. Learn to verify hostname, FQDN, and DNS identity....
The kernel ring buffer (dmesg) contains critical hardware diagnostics, driver messages, and OOM killer events. Learn to analyze dmesg output for proactive server maintenance....
Cgroups control resource allocation for processes and containers. Learn to audit CPU, memory, and I/O limits across systemd slices and container workloads....