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Introduction:
Linux is the backbone of modern IT infrastructure, cybersecurity, and cloud computing. Whether you’re a sysadmin, ethical hacker, or DevOps engineer, mastering Linux commands is non-negotiable. This cheat sheet from Azul School condenses critical commands for file management, networking, security, and automation—saving you time and boosting productivity.
Learning Objectives:
- Master essential Linux commands for system navigation and file management.
- Learn network and security tools like
ssh,iptables, andcron. - Optimize workflows with keyboard shortcuts and automation scripts.
1. File & Directory Navigation
Command:
ls -la /path/to/directory
What It Does:
Lists all files (including hidden ones) with detailed permissions, ownership, and timestamps.
How to Use:
ls -l: Long listing format.ls -a: Shows hidden files (e.g.,.bashrc).- Combine flags for comprehensive output.
2. Permission Management
Command:
chmod 755 script.sh
What It Does:
Sets read/write/execute permissions for the owner (7) and read/execute for others (5).
How to Use:
– `7` = rwx (owner).
– `5` = r-x (group/others).
– Critical for securing scripts and sensitive files.
3. Network Security with SSH
Command:
ssh -i ~/.ssh/key.pem [email protected]
What It Does:
Securely connects to a remote server using a private key.
How to Use:
- Replace `key.pem` with your key file.
- Always disable password authentication in
/etc/ssh/sshd_config.
4. Firewall Hardening with iptables
Command:
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
What It Does:
Allows SSH traffic (port 22) through the firewall.
How to Use:
- Chain (
-A INPUT): Append rule to inbound traffic. - Protocol/port (
-p tcp --dport 22): Specify service. - Action (
-j ACCEPT): Permit traffic.
5. Process Management
Command:
kill -9 $(pgrep malware_process)
What It Does:
Force-terminates a malicious or unresponsive process.
How to Use:
pgrep: Finds the process ID.-9: SIGKILL (irrecoverable termination).
6. Automation with Cron
Command:
crontab -e
What It Does:
Opens the cron table to schedule tasks (e.g., backups, scans).
How to Use:
- Add lines like `0 3 /path/to/backup.sh` for daily 3 AM backups.
7. File Compression for Efficient Storage
Command:
tar -czvf archive.tar.gz /path/to/files
What It Does:
Creates a compressed tarball (gzip) of specified files.
How to Use:
- Flags: `-c` (create), `-z` (gzip), `-v` (verbose), `-f` (filename).
What Undercode Say:
- Key Takeaway 1: Linux proficiency is a must for cybersecurity and IT roles—this cheat sheet bridges the gap between basics and advanced usage.
- Key Takeaway 2: Automating tasks (e.g., cron, bash scripts) reduces human error and frees time for critical security monitoring.
Prediction:
As Linux dominates cloud and containerized environments (e.g., Kubernetes, Docker), demand for sysadmins with CLI expertise will surge. Meanwhile, attackers increasingly target misconfigured Linux systems—making command-line security skills a top priority for 2025 and beyond.
Download the Full Cheat Sheet Here: Azul School Linux Commands Guide
Note: Always test commands in a sandbox before production use. Misuse of `rm -rf` or `iptables` can cause irreversible damage.
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IT/Security Reporter URL:
Reported By: Activity 7357818484707278849 – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
