Essential Linux Commands for Cybersecurity

Introduction

• Focus on essential Linux commands and their flags
• Importance for ethical hacking and cybersecurity
• Advanced applications (e.g., Metasploit, nmap, Hydra, etc.) available in other videos

Navigating the Linux File System

Using the Terminal

• ls: Lists directory contents
  • ls -l: Long listing format
    • Shows links, permissions (owner, group, everyone), owner, group, size, and modification date
  • ls -a: Includes hidden files
  • ls -t: Sort by modification time
  • ls -h: Human-readable sizes
  • Combine flags: ls -lath
• cd: Change directory
  • cd -: Move to the previous directory
  • cd ..: Move up one directory level
  • cd ~: Go to home directory
  • Use tab for auto-completion
• pwd: Print working directory

Manipulating Files and Directories

Creating and Managing Files

• touch: Create empty files
  • Example: touch file1 file2 file3
• mkdir: Create directories
  • Example: mkdir dir1
  • Recursive creation: mkdir -p parent/child
  • With permissions: mkdir -m 777 dir

Copying and Removing Files

• cp: Copy files and directories
  • Example: cp file1 file2
  • Recursive copy: cp -r dir1 dir2
• rm: Remove files and directories
  • Example: rm file1
  • Recursive and forceful: rm -rf dir

Moving and Renaming Files

• mv: Move or rename files and directories
  • Example: mv oldname newname
• clear: Clear the terminal screen

Disk Usage and Permissions

Disk Usage

• du: Disk usage
  • Human-readable: du -h
  • Summary: du -sh

File Permissions

• chmod: Change file permissions
  • Example: chmod u+x file
  • Numeric mode: chmod 777 file
• chown: Change file owner
  • Example: chown user:group file

Viewing and Editing Files

Viewing Files

• cat: Concatenate and display files
  • Combine files: cat file1 file2 > file3
  • Append: cat file >> file
• tail: View end of files
  • Example: tail file
  • Follow file changes: tail -f file
• head: View beginning of files
  • Example: head file
• less: View files one page at a time
  • Example: less file
• grep: Search text using patterns
  • Example: grep 'pattern' file

Text Editors

• nano: Simple text editor
• vi: More complex, feature-rich text editor

Process Management

Monitoring and Controlling Processes

• ps: Process status
  • Detailed view: ps aux
• top: Real-time process monitoring
  • Filter by user: top -u user
• kill: Terminate processes
  • Example: kill pid
  • Forceful kill: kill -9 pid
• jobs: List background jobs
• fg: Bring background job to foreground

Networking Commands

• ifconfig: Network interface configuration
• ip: Newer network interface configuration
  • Example: ip a
  • Show routes: ip route
• netstat: Network statistics
  • Listening ports: netstat -l
• ss: Socket statistics
  • Example: ss -t
• ssh: Secure shell
  • Example: ssh user@host
• scp: Secure copy
  • Example: scp file user@host:/path
• rsync: Remote sync
  • Example: rsync -avz source destination

System Information

• uname: System information
  • Detailed: uname -a
• df: Disk free space
  • Human-readable: df -h

Searching and Archiving

Finding Files

• find: Search for files
  • Example: find /path -name filename
  • By size: find /path -size +1M
  • By modification time: find /path -mtime -30

Archiving and Compressing

• tar: Archive files
  • Example: tar czf archive.tar.gz files
  • Extract: tar xzf archive.tar.gz
• gzip: Compress files
  • Example: gzip file
  • Decompress: gunzip file.gz

User and Group Management

• useradd: Add a new user
  • Example: useradd username
  • With home directory: useradd -m username
• userdel: Delete a user
  • Example: userdel username
  • With home directory: userdel -r username
• groupadd: Add a new group
  • Example: groupadd groupname
• groupdel: Delete a group
  • Example: groupdel groupname

Conclusion

• Focus on learning these essential commands
• Further videos available for advanced topics
• Encouragement to subscribe and follow for more content