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SysAdmin
Cheatsheet
A comprehensive quick-reference for sysadmins who need working commands fast - no fluff,
no theory. Built from real-world daily use across Windows Server, Linux, and cloud environments.
- Networking: OSI, TCP/UDP, DNS, CIDR, subnetting, ports, and VPN technologies
- Security & hardening: threats, cryptography, authentication, certificates, and firewall rules
- OS & commands: Linux and Windows Server, PowerShell, AD, SSH, and log paths
- Cloud: AWS and Azure services, M365, Entra ID, Exchange Online, and Intune
- DevOps tools, monitoring platforms, and diagnostic references
cheatsheet.hjalti.me →
# Networking - listening ports
$ ss -tlnp
tcp LISTEN 0.0.0.0:22 sshd
tcp LISTEN 0.0.0.0:443 nginx
# Security - failed auth attempts
$ grep "Failed" /var/log/auth.log
# Windows - security event log
PS> Get-WinEvent
-LogName Security
-MaxEvents 50
# M365 - trace email flow
PS> Get-MessageTrace
-SenderAddress user@contoso.com
-StartDate (Get-Date).AddDays(-2)
# Entra ID - trigger delta sync
PS> Start-ADSyncSyncCycle
-PolicyType Delta
# Docker - start & tail logs
$ docker compose up -d
$ docker logs -f web