Tag: linux

Is fail2ban Actually Working? Here's How to Check

Verify fail2ban is protecting you: check jails, test bans, monitor logs, common misconfiguration, and unban IPs when needed.

Diagnosing Slow Linux Boot with systemd-analyze

Use systemd-analyze to find which services are slowing down boot. Fix the bottlenecks.

SSHFS: Ditch SCP & Access Remote Files

SSHFS mounts remote filesystems over SSH so you can browse and edit files locally — faster than scp for interactive work.

How to Actually Read `systemctl status` Output

Decode systemctl status: Active state, CGroup processes, recent logs, loaded/enabled state. What each field tells you.

SSH Agent Forwarding: How It Works

Understand SSH agent forwarding security risks. When it's safe (almost never), and better alternatives like ProxyJump for jump hosts.

Is Your Linux Server Destroying Its SSD?

Check SSD health, find excessive write patterns, use noatime, move logs to tmpfs to extend lifespan.

journalctl Queries Every Sysadmin Needs

Essential journalctl commands: -u, -f, --since, -p, -k, -b, --no-pager, JSON output. The queries you need on a broken server at 2 AM.

Why Your SSH Connection Keeps Dropping

Fix SSH timeouts: ServerAliveInterval, ServerAliveCountMax, ClientAliveInterval. Understand NAT, firewalls, and TCP keepalive.

Why Your Cron Job Is Failing Silently

PATH is different in cron, stdout is muted, and MAILTO breaks silently. Learn cron traps and how to debug them.

SSH Multiplexing: Stop Reconnecting Every Time

Master SSH ControlMaster, ControlPath, and ControlPersist. Reuse connections for lightning-fast SSH, SCP, and rsync operations.

The Linux OOM Killer: Why It's Killing Your App

Understand the OOM killer, read dmesg logs, protect critical processes with oom_score_adj.

find Flags You Keep Forgetting

Practical find command examples: -mtime, -newer, -type, -exec vs xargs, -not, size filters. The patterns you google every time.