Tag: linux
All the articles with the tag "linux".
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The Firewall Rule Order That's Breaking Your Setup
Firewall rules are evaluated top-down, first match wins. One misplaced ALLOW rule silently defeats all security.
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Sticky Bit, Setuid, Setgid: Linux Special Permissions Explained
Understand sticky bit, setuid, and setgid: what they do, how to set them, security implications, and real-world use cases.
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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.
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Diagnosing Slow Linux Boot with systemd-analyze
Use systemd-analyze to find which services are slowing down boot. Fix the bottlenecks.
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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.
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How to Actually Read `systemctl status` Output
Decode systemctl status: Active state, CGroup processes, recent logs, loaded/enabled state. What each field tells you.
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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.
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Is Your Linux Server Destroying Its SSD?
Check SSD health, find excessive write patterns, use noatime, move logs to tmpfs to extend lifespan.
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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.
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Why Your SSH Connection Keeps Dropping
Fix SSH timeouts: ServerAliveInterval, ServerAliveCountMax, ClientAliveInterval. Understand NAT, firewalls, and TCP keepalive.
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ss Is the New netstat (And It's Better)
netstat is deprecated. ss is faster, shows more, and does everything netstat did—better.
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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.