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File Commands
– `ls` – Directory listing
– `ls -l` – Long listing format
– `ls -a` – List all files including hidden files
– `cd /path/to/directory` – Change directory
– `pwd` – Display the current working directory
– `mkdir directory_name` – Create a new directory
– `rmdir directory_name` – Remove an empty directory
– `rm file_name` – Remove a file
– `rm -r directory_name` – Remove a directory and its contents recursively
– `touch file_name` – Create or update a file
– `cat file_name` – Concatenate and display the file content
– `more file_name` – View file content page by page
– `less file_name` – Improved viewing of file content over `more`
– `cp source_file target_file` – Copy files from source to target
– `mv old_name new_name` – Rename or move a file/directory
SSH (Secure Shell)
– `ssh user@host` – Connect to host as user
– `ssh -p port user@host` – Connect using a specific port
– `ssh-keygen -t rsa` – Generate RSA key pair
– `ssh-copy-id user@host` – Copy your key to the remote server for password-less login
Searching
– `grep pattern files` – Search for a pattern in files
– `grep -r pattern dir` – Recursively search for a pattern in a directory
– `find dir -name name` – Find files starting with `name` in a directory
– `locate file_name` – Find files by name (uses a database)
Process Management
– `ps aux` – Display your currently active processes
– `ps aux | grep process_name` – Find a process named `process_name`
– `top` – Display all running processes
– `kill pid` – Kill a process with a given PID
– `killall process_name` – Kill all processes named `process_name`
– `bg` – List stopped or background jobs; resume a stopped job in the background
– `fg` – Bring the most recent job to the foreground
File Permissions
– `chmod +x file_name` – Make a file executable
– `chmod 755 file_name` – Set read and execute permissions for owner and read for others
– `chown user:group file_name` – Change file owner and group
Networking
– `ifconfig` – Display all network interfaces and IP addresses
– `ping host` – Send ICMP echo request to host
– `traceroute host` – Display the route packets take to a network host
– `netstat -tulnp` – Display listening ports and their applications
Archiving and Compression
– `tar cf archive_name.tar files` – Create a tar archive containing files
– `tar xf archive_name.tar` – Extract files from a tar archive
– `gzip file_name` – Compress a file and rename it to `file.gz`
– `gunzip file.gz` – Decompress `file.gz` back to the original
System Info and Management
– `uname -a` – Show system and kernel info
– `df -h` – Display free disk space in a human-readable form
– `du -sh directory_name` – Show disk usage of a directory in human-readable form
– `free -m` – Show free and used memory in MB
Misc Commands
– `man command_name` – Show manual for a command
– `echo “text”` – Display a message on the screen
– `date` – Display the current date and time
– `uptime` – Show how long the system has been running
You Should Know:
Advanced Linux Commands for Cybersecurity
1. Log Analysis with `grep` and `awk`
grep "Failed password" /var/log/auth.log | awk '{print $9}' | sort | uniq -c | sort -nr
– Detects brute-force attacks by counting failed login attempts.
2. Network Traffic Monitoring with `tcpdump`
tcpdump -i eth0 'port 80' -w http_traffic.pcap
– Captures HTTP traffic for forensic analysis.
3. File Integrity Checking with `md5sum`
md5sum /etc/passwd
– Verifies critical system files for unauthorized changes.
4. Process Monitoring with `lsof`
lsof -i :22
– Lists processes using SSH port (22).
5. Firewall Management with `iptables`
iptables -A INPUT -p tcp --dport 22 -j DROP
– Blocks SSH brute-force attacks.
6. Memory Forensics with `strings`
strings /dev/mem | grep "password"
– Extracts plaintext passwords from memory (requires root).
7. Automated Security Audits with `lynis`
lynis audit system
– Scans for vulnerabilities and misconfigurations.
8. Password Cracking with `john`
john --wordlist=/usr/share/wordlists/rockyou.txt hashes.txt
– Tests password strength (ethical hacking only).
What Undercode Say
Linux commands are the backbone of cybersecurity operations. Mastering these commands enhances efficiency in penetration testing, incident response, and system hardening. Automation with scripting (bash, Python) further amplifies productivity.
Expected Output:
A well-structured cheat sheet with actionable commands for IT and cybersecurity tasks, supplemented with advanced techniques for real-world applications.
Prediction
As cyber threats evolve, Linux-based tools will remain critical for defense. Expect increased integration of AI-driven command-line utilities (mlocate, fzf) for faster threat detection.
Relevant URL: Linux Command Line for Pentesting
IT/Security Reporter URL:
Reported By: Shamseer Siddiqui – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
