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.
All the articles with the tag "linux".
Verify fail2ban is protecting you: check jails, test bans, monitor logs, common misconfiguration, and unban IPs when needed.
Use systemd-analyze to find which services are slowing down boot. Fix the bottlenecks.
SSHFS mounts remote filesystems over SSH so you can browse and edit files locally — faster than scp for interactive work.
Decode systemctl status: Active state, CGroup processes, recent logs, loaded/enabled state. What each field tells you.
Understand SSH agent forwarding security risks. When it's safe (almost never), and better alternatives like ProxyJump for jump hosts.
Check SSD health, find excessive write patterns, use noatime, move logs to tmpfs to extend lifespan.
Essential journalctl commands: -u, -f, --since, -p, -k, -b, --no-pager, JSON output. The queries you need on a broken server at 2 AM.
Fix SSH timeouts: ServerAliveInterval, ServerAliveCountMax, ClientAliveInterval. Understand NAT, firewalls, and TCP keepalive.
netstat is deprecated. ss is faster, shows more, and does everything netstat did—better.
PATH is different in cron, stdout is muted, and MAILTO breaks silently. Learn cron traps and how to debug them.
Master SSH ControlMaster, ControlPath, and ControlPersist. Reuse connections for lightning-fast SSH, SCP, and rsync operations.
Understand the OOM killer, read dmesg logs, protect critical processes with oom_score_adj.