🔍Why Logs Matter
Logs are essential for troubleshooting, monitoring performance, hardening security, and auditing compliance. Whether you're managing a single VM or a fleet of servers, knowing where and how to analyze logs quickly can save you hours—or worse, downtime.
🐧 Linux Distributions & Log Locations
All Linux distros log to /var/log/ by default, but file structure varies slightly:
Common files of note:
Kernel & boot messages:
dmesg,/var/log/dmesg,/var/log/kern.log(Debian).Application logs: e.g.,
/var/log/nginx/access.log,/var/log/httpd/error.log.Mail logs (
/var/log/maillog), firewall logs, audit/audit.log, btmp, wtmp, utmp.
⚙️ Using systemd and journalctl
All distros above use systemd, and logs can be accessed via journalctl:
View all logs:
journalctlFilter by unit (e.g. nginx):
journalctl -u nginx.serviceTime-range filtering:
journalctl --since "2025-06-29 00:00" --until "2025-06-30 23:59"Follow live updates:
journalctl -u sshd -fUseful flags:
-p errto show errors only-kfor kernel logs-bfor current boot session
🪟 Windows Server 2019 & 2022: Event Viewer
Analysing logs via Event Viewer (WN 2019/2022):
Windows Logs:
Application: application-level events
Security: login attempts, policy changes
System: OS-level issues and driver errors
Applications and Services Logs:
Specific services (e.g., IIS, DNS)
Microsoft → Windows logs, e.g., HardwareEvents or Windows Update
Forwarded Events if collecting logs from other machines
Custom Views:
Set up filters for RDP, failures, or hardware alerts to streamline incident identification.ETW & PowerShell:
Efficient event export:Get-WinEvent -FilterHashtable @{LogName='System'; StartTime=(Get-Date).AddDays(-1)} | Export-Csv system-events.csv
🛡️ Adding Proactive Monitoring & Security
Consider installing:
Fail2Ban on Linux (supports AlmaLinux, Ubuntu, Debian):
sudo apt install fail2ban # Ubuntu/Debian
sudo dnf install fail2ban # Alma/Rocky
Blocks malicious IPs based on auth log patterns.
Lynis for compliance checks:
sudo apt install lynis # Debian/Ubuntu
Performs system audits.