Networking & Remote Access

Termux से SSH, FTP, VNC, और रिमोट एक्सेस सीखें

1. Network Types

Different types of Networks

🌐 LAN (Local Area Network)

Home या Office में limited area के लिए

$ Example: Home WiFi (192.168.1.x)

🌍 WAN (Wide Area Network)

Large geographical area में connect करता है

$ Example: Internet connection

🏙️ MAN (Metropolitan Area Network)

City-wide network

$ Example: City-wide cable network

📱 PAN (Personal Area Network)

Personal devices के बीच

$ Example: Bluetooth, NFC

2. Network Components

Networking Hardware और Devices

🔄 Router

Different networks के बीच data forward करता है

🔌 Switch

LAN में devices को connect करता है

🔗 Hub

Multiple devices को single connection पर connect करता है

🌉 Bridge

दो network segments को connect करता है

🚪 Gateway

Network को external world से connect करता है

🛡️ Firewall

Network traffic को filter और block करता है

3. IP Addresses

IP Addressing System

🔢 IPv4 (Internet Protocol version 4)

32-bit address, example: 192.168.1.1

$ Range: 0.0.0.0 to 255.255.255.255

🔢 IPv6 (Internet Protocol version 6)

128-bit address, example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334

$ More addresses available than IPv4

🔒 Private IP Addresses

192.168.0.0 to 192.168.255.255

10.0.0.0 to 10.255.255.255

172.16.0.0 to 172.31.255.255

🌐 Public IP Addresses

Internet पर directly accessible addresses

$ Example: 8.8.8.8 (Google DNS)

4. Network Protocols

Communication Protocols

🌊 TCP/IP

Transmission Control Protocol/Internet Protocol

$ Reliable, connection-oriented

⚡ UDP

User Datagram Protocol

$ Fast, connectionless (gaming, streaming)

🌐 HTTP/HTTPS

Web browsing protocol

$ Port 80 (HTTP), 443 (HTTPS)

📁 FTP

File Transfer Protocol

$ Port 20, 21

🔐 SSH

Secure Shell for remote access

$ Port 22, encrypted connection

🖥️ RDP

Remote Desktop Protocol

$ Port 3389 (Windows)

5. OSI Model (7 Layers)

Open Systems Interconnection Model

Application Layer

User applications (HTTP, FTP, SMTP, SSH)

Presentation Layer

Data translation, encryption (SSL/TLS)

Session Layer

Session management (NetBIOS, RPC)

Transport Layer

End-to-end communication (TCP, UDP)

Network Layer

Routing and logical addressing (IP, ICMP)

Data Link Layer

Physical addressing (MAC, Ethernet, Switching)

Physical Layer

Physical transmission (Cables, WiFi, Signals)

6. Network Security

Protecting Your Network

🛡️ Firewall

Network traffic को monitor और block करता है

$ ufw enable (Ubuntu/Linux firewall)

🔒 VPN (Virtual Private Network)

Encrypted, private connection

$ OpenVPN, WireGuard, NordVPN, etc.

🔐 Encryption

Data को secure code में convert करना

$ AES, RSA, SSL/TLS protocols

👁️ IDS (Intrusion Detection System)

Unauthorized access detect करता है

$ Snort, Suricata

7. Network Attacks (Educational Purpose Only)

Common Attack Types - सिर्फ सीखने के लिए!

⚠️ IMPORTANT: ये attacks सिर्फ अपने system या authorized testing पर ही करें। बिना permission किसी और system पर test करना illegal है!

💥 DDoS (Distributed Denial of Service)

Multiple systems से attack करके service को down करना

$ Mitigation: Firewall, rate limiting, CDN

🎣 Phishing

Fake websites/emails से sensitive info steal करना

$ Mitigation: Email filters, user awareness, 2FA

👥 MITM (Man-in-the-Middle)

दो parties के बीच में घुसकर communication intercept करना

$ Mitigation: End-to-end encryption, HTTPS

💉 SQL Injection

Database में malicious SQL commands inject करना

$ Mitigation: Input validation, parameterized queries

🔗 XSS (Cross-Site Scripting)

Websites में malicious JavaScript inject करना

$ Mitigation: Input sanitization, CSP headers

8. Network Tools

Essential Networking Tools in Termux

🗺️ Nmap (Network Mapper)

Network discovery और security auditing

$ pkg install nmap

nmap -sn 192.168.1.0/24 (network discovery)

nmap -sV -p 1-1000 target (version detection)

👁️ Wireshark

Network protocol analyzer - packets capture और analyze करता है

$ pkg install wireshark

🔌 Netcat (nc)

Network utility - read/write network connections

$ pkg install netcat

nc -l 8080 (listen on port 8080)

echo "hello" | nc localhost 8080

9. Remote Access Protocols

Remote System Access Methods

🖥️ RDP (Remote Desktop Protocol)

Windows के लिए GUI remote access

$ Port 3389 - Full desktop control

🔐 SSH (Secure Shell)

Linux/Unix systems के लिए command-line access

$ Port 22 - Encrypted, secure

📺 VNC (Virtual Network Computing)

Cross-platform GUI remote access

$ Port 5900+ - Any OS compatible

📞 Telnet

Unencrypted text-based remote access (NOT secure!)

$ Port 23 - Avoid using, unencrypted

10. SSH Setup in Termux

SSH Server Install और Configure करें

Step 1: Install OpenSSH

$ pkg update && pkg upgrade

$ pkg install openssh

Step 2: Set Password

$ passwd

New password enter करें और confirm करें

Step 3: Start SSH Server

$ sshd# Start SSH server

Step 4: Find Your IP

$ ip addr show wlan0# For WiFi

$ ip addr show wlan0 | grep inet

Step 5: Connect from PC

# Windows PowerShell/CMD:

$ ssh termux@192.168.1.100

# Linux/Mac Terminal:

$ ssh termux@192.168.1.100

11. SSH Key Authentication

Password के बिना SSH Access

Generate SSH Key Pair on PC:

PC$ ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

Enter दबाएं (default path accept करें)

Copy Public Key to Termux:

PC$ ssh-copy-id termux@192.168.1.100

OR Manual Method:

PC$ cat ~/.ssh/id_rsa.pub

termux$ mkdir ~/.ssh

termux$ echo "YOUR_PUBLIC_KEY" >> ~/.ssh/authorized_keys

termux$ chmod 700 ~/.ssh

termux$ chmod 600 ~/.ssh/authorized_keys

✅ अब password के बिना SSH connect हो जाएगा!

12. SCP for File Transfer

Secure File Copy Protocol

Upload to Termux:

PC$ scp file.txt termux@192.168.1.100:~/

PC$ scp -r folder/ termux@192.168.1.100:~/

Download from Termux:

PC$ scp termux@192.168.1.100:~/file.txt ./

PC$ scp -r termux@192.168.1.100:~/folder/ ./

⚠️ IMPORTANT DISCLAIMER

ये content सिर्फ Educational Purpose के लिए है।

• सिर्फ अपने system या permission वाली practice पर use करें
• बिना permission किसी system को test/crack करना illegal है
• Cyber Crime के लिए सख्त सज़ा है
• सिर्फ Learning और Security Improvement में use करें
• Local Laws का पालन करें