Raj Computre Institute, Rawanwadi

  🐧 Linux Commands for File & Network Security Security professionals mainly use Linux to: ✅ Protect files ✅ Monitor users ✅ Control permissions ✅ Scan networks ✅ Detect attacks 🔐 File Security Commands 📁 1️⃣ List Files with Permissions ls -l Shows: -rwxr-xr-- Owner | Group | Others 🔑 2️⃣ Change Permissions chmod 755 file.sh chmod 600 secret.txt 755 → executable 600 → private file 👤 3️⃣ Change Ownership chown user:group file.txt 🔍 4️⃣ Find Sensitive Files find / -perm -4000 2>/dev/null Finds SUID files (security risk). 📄 5️⃣ Check File Integrity sha256sum file.txt Used to verify file changes. 🗂️ 6️⃣ Monitor File Changes stat file.txt Shows access, modify time. 🔎 7️⃣ Search Inside Files grep "password" file.txt Finds keywords in files/logs. 👥 User & Access Security 👤 8️⃣ Check Logged-in Users who w 🔐 9️⃣ Check User Privileges id sudo -l 🚫 🔟 Lock User Account passwd -l username 🌐 Net...

  🐧 Introduction to Linux for Security Professionals 🔹 Why Linux for Security? Linux is the most important OS for cyber security because: ✔ Open Source ✔ Highly secure ✔ Powerful command line ✔ Used on servers ✔ Best for penetration testing ✔ Customizable Most security tools are built for Linux. 🔹 Popular Linux Distros for Security Kali Linux – Penetration testing Parrot OS – Security + privacy Ubuntu – General + servers RedHat – Enterprise security 👉 Kali Linux is most popular for hackers and security professionals. 🔹 Linux Architecture (Simple) User → Shell → Kernel → Hardware Shell – Command interpreter Kernel – Core of OS File System – Stores data 🔹 Linux File System Structure Directory Use / Root /home User files /etc Config files /bin Commands /var Logs /tmp Temporary files /usr Programs 🔹 Basic Linux Commands (Security Must-Know) 📁 File Commands ls # list files cd # change directory pwd ...

  🛡️ Antivirus & Firewall Configuration Security in Windows mainly uses: ✅ Microsoft Defender Antivirus ✅ Windows Defender Firewall They protect your system from viruses, malware, hackers, and unauthorized access . 🦠 Antivirus Configuration (Windows Defender) 🔹 What is Antivirus? 👉 Antivirus software detects, blocks, and removes malware like: Virus Trojan Worm Ransomware Spyware 🔹 Open Antivirus Go to: Settings → Privacy & Security → Windows Security → Virus & Threat Protection 🔹 Important Antivirus Settings ✅ 1️⃣ Real-Time Protection 👉 Scans files while working. ✔ Keep it ON Path: Virus & Threat Protection → Manage Settings → Real - time protection ✅ 2️⃣ Scan Options Types: Quick Scan – Fast Full Scan – Entire PC Custom Scan – Selected files Offline Scan – Deep malware ✅ 3️⃣ Cloud Protection 👉 Uses cloud intelligence to detect new threats. ✔ Enable it. ✅ 4️⃣ Ransomware Protection ?...

  🔐 User Account Control (UAC) & Permissions 🔹 What is User Account Control (UAC)? 👉 UAC is a Windows security feature that prevents unauthorized changes to the system. Whenever an app tries to: Install software Change system settings Access protected files 👉 Windows shows a permission popup asking for approval. 🔹 Why UAC is Important? Stops malware Protects system files Prevents accidental changes Requires admin approval 🔹 How UAC Works Normal work runs with limited rights Admin rights only when approved Popup asks: Yes / No 🔹 UAC Levels Open: Control Panel → User Accounts → Change UAC settings Levels: Always Notify Default Notify without dimming Never Notify (Not recommended) 👤 User Accounts in Windows Windows has different account types. 🔹 Types of Accounts ✅ Administrator Full control Install software Change policies ✅ Standard User Limited control Cannot change sys...

  🔐 Windows Security Settings & Policies Windows provides built-in tools to protect your system, data, and network from viruses, hackers, and unauthorized users. 🔹 What is Windows Security? 👉 Windows Security is a collection of features that protect: Device Network User accounts Data Main tool: Windows Security (Defender) 🛡️ Main Parts of Windows Security 1️⃣ Virus & Threat Protection 👉 Protects against malware and viruses. Features: Real-time protection Quick scan Full scan Threat history Ransomware protection Use: Settings → Privacy & Security → Windows Security 2️⃣ Firewall & Network Protection 👉 Controls incoming and outgoing traffic. Types of Networks: Domain Private Public Functions: Block unauthorized access Allow safe apps 3️⃣ Account Protection 👉 Protects user login. Includes: Windows Hello (PIN, Face, Fingerprint) Dynamic Lock Password policies 4️⃣ App & ...

  🌐 Network Topologies & Cable Types 🔹 What is Network Topology? 👉 Network Topology is the layout or structure of a network — how computers and devices are connected. 🧩 Types of Network Topologies ⭐ 1️⃣ Bus Topology 👉 All devices connected to a single cable (backbone) . Features: Low cost Easy to install Slow if many devices Disadvantage: If main cable fails, whole network fails ⭐ 2️⃣ Star Topology 👉 All devices connect to a central device (switch/hub) . Features: Easy troubleshooting High performance Most popular Disadvantage: If switch fails, network down ⭐ 3️⃣ Ring Topology 👉 Devices connected in circular form . Features: Equal access Data flows in one direction Disadvantage: One break stops network ⭐ 4️⃣ Mesh Topology 👉 Every device connects to every other device. Features: Very reliable High security Disadvantage: Expensive Complex ⭐ 5️⃣ Tree Topology 👉 Combination of st...

  🌐 Network Devices Network devices connect, control, and secure communication between computers and networks. 🛜 1️⃣ Router 👉 A router connects different networks together. Main Work: Routes data between LAN and Internet Assigns IP addresses (DHCP) NAT (Private → Public IP) Internet sharing Used At: Home networks Offices ISPs Example: WiFi Router 🔀 2️⃣ Switch 👉 A switch connects devices inside a LAN . Main Work: Uses MAC address Sends data only to correct device Faster than hub Used At: Office LAN Computer labs Layers: Layer 2 (MAC based) Layer 3 (IP based) 🔥 3️⃣ Firewall 👉 A firewall protects the network from attacks . Main Work: Allows or blocks traffic Security rules Prevents hacking Filters packets Types: Hardware firewall Software firewall Network firewall Example: Windows Defender Firewall 🔹 Difference Between Router, Switch & Firewall Device Work Layer Use Route...

  🌐 OSI Model & TCP/IP Model Networking models explain how data travels from one computer to another in layers. 🧱 OSI Model (Open Systems Interconnection) 👉 Developed by ISO . 👉 Has 7 Layers . 🔹 OSI 7 Layers (Top to Bottom) 7️⃣ Application Layer 👉 User interacts with network. Examples: HTTP FTP SMTP 6️⃣ Presentation Layer 👉 Data formatting and security. Functions: Encryption Compression Translation 5️⃣ Session Layer 👉 Manages sessions. Functions: Session setup Control Termination 4️⃣ Transport Layer 👉 End-to-end delivery. Protocols: TCP UDP Functions: Flow control Error control 3️⃣ Network Layer 👉 Routing and addressing. Protocols: IP ICMP Devices: Router 2️⃣ Data Link Layer 👉 Node to node delivery. Functions: Framing MAC addressing Error detection Devices: Switch 1️⃣ Physical Layer 👉 Actual transmission. Examples: Cable Signals Voltage De...