Important-Commands.md

System Essentials (Ubuntu)

A quick, practical set of commands for keeping your system patched, watching authentication activity, and checking what’s running.

Updates

sudo apt update && sudo apt upgrade -y

Authentication log (failed attempts)

sudo cat /var/log/auth.log | grep "Failed"

Authentication log (live tail)

sudo tail -f /var/log/auth.log

Fail2ban basics

sudo systemctl start fail2ban
sudo fail2ban-client status

Browser profile isolation (Brave/Firefox)

Use separate profiles for different contexts (e.g., GitHub, Fiverr, banking) to isolate cookies and sessions.

Launch Firefox Profile Manager:

firefox -P

Encrypt your home directory

sudo apt install ecryptfs-utils
ecryptfs-migrate-home -u $USER

If you already use full‑disk encryption, per-user home encryption may be unnecessary.

Continuous monitoring

Install and run Lynis (security auditing):

sudo apt install lynis -y
sudo lynis audit system

View processes:

htop

Network listeners:

sudo apt install net-tools
sudo netstat -tulpn

Quick reference

Category	Tool/Command	Purpose
System Updates	apt update && apt upgrade	Stay patched
Firewall	ufw	Block unauthorized access
Intrusion Detection	fail2ban, lynis	Detect & block attacks
Browser Isolation	Brave/Firefox profiles	Keep accounts separate
VPN	ProtonVPN / Mullvad	Encrypt traffic
2FA	Authenticator app	Secure logins
Monitoring	htop, netstat, auth.log	Watch system behavior