Nmap Kya Hai? Network Scanning Ka Complete Beginner Guide
Jab hum kisi network se connected hote hain aur internet, email ya web services use karte hain, tab do important questions saamne aate hain:
- Network me kaun-kaun se devices online hain?
- Un devices par kaun si services chal rahi hain?
Example ke liye, kisi system par SSH server chal raha ho sakta hai aur kisi dusre system par Web Server.
In sab information ko efficiently collect karne ke liye Cyber Security professionals ek powerful tool use karte hain jiska naam hai Nmap (Network Mapper).
Nmap Kya Hai?
Nmap ek Open-Source Network Scanning Tool hai jo 1997 me release hua tha. Iska use network ke andar live hosts discover karne, open ports identify karne aur running services ki information nikalne ke liye kiya jata hai.
Aaj Nmap Cyber Security, Penetration Testing aur Network Administration ka ek important tool ban chuka hai.
Nmap Kya-Kya Kar Sakta Hai?
Nmap ki help se aap:
- Live Hosts discover kar sakte hain
- Open Ports find kar sakte hain
- Running Services identify kar sakte hain
- Service Versions detect kar sakte hain
- Operating System ka pata laga sakte hain
- Scan Reports save kar sakte hain
Live Hosts Kaise Discover Karein?
Agar hume pata lagana ho ki network me kaun se devices online hain, to hum Ping Scan use kar sakte hain.
nmap -sn 192.168.0.0/24
-sn Kya Karta Hai?
Ye option sirf Host Discovery karta hai.
Isse pata chalta hai ki kaun se systems online hain, lekin ye ports scan nahi karta.
Target Specify Karne Ke Different Methods
1. IP Range
nmap 192.168.0.1-10
Ye 192.168.0.1 se 192.168.0.10 tak sabhi IP scan karega.
2. Subnet
nmap 192.168.0.0/24
Poora subnet scan karega.
3. Hostname
nmap example.com
Domain ya hostname ko scan karega.
Port Scanning
Host discover karne ke baad next step hota hai open ports identify karna.
Ports hume batate hain ki system par kaunsi services available hain.
TCP Connect Scan (-sT)
nmap -sT TARGET_IP
Ye TCP Three-Way Handshake complete karta hai.
Process:
- SYN bhejta hai
- SYN-ACK receive karta hai
- ACK bhejta hai
Agar connection establish ho jaye to port open maana jata hai.
SYN Scan (-sS) – Stealth Scan
nmap -sS TARGET_IP
Ye sirf SYN packet bhejta hai.
Agar port open ho to target SYN-ACK bhejta hai aur Nmap connection complete karne ke bajay RST bhej deta hai.
Isliye ise Stealth Scan bhi kaha jata hai kyunki ye kam logs generate karta hai.
UDP Scan (-sU)
nmap -sU TARGET_IP
UDP based services detect karne ke liye use hota hai.
Common UDP Services:
- DNS
- DHCP
- NTP
- SNMP
Specific Ports Scan Karna
Fast Scan
nmap -F TARGET_IP
Top 100 most common ports scan karta hai.
Port Range Scan
nmap -p 1-1024 TARGET_IP
Port 1 se 1024 tak scan karega.
All Ports Scan
nmap -p- TARGET_IP
Ye 1 se 65535 tak ke saare ports scan karega.
Operating System Detection
Target machine kis Operating System par chal rahi hai ye jaanne ke liye:
nmap -O TARGET_IP
Example Output:
- Linux
- Windows
- FreeBSD
Nmap network fingerprinting ke basis par OS ka guess karta hai.
Service Version Detection
Agar aapko sirf service nahi balki uska version bhi pata karna ho:
nmap -sV TARGET_IP
Example:
22/tcp open ssh OpenSSH 8.9p1
Yani SSH service OpenSSH version 8.9p1 run kar rahi hai.
Aggressive Scan (-A)
nmap -A TARGET_IP
Ye multiple advanced features ek saath enable karta hai:
- OS Detection
- Service Version Detection
- Traceroute
- Additional Information Gathering
Host Discovery Skip Karna
Kabhi-kabhi firewall ICMP requests block kar deta hai.
Aise case me:
nmap -Pn TARGET_IP
Nmap host ko online maan kar directly port scan start kar deta hai.
Timing Templates
Nmap scan speed ko control karne ke liye timing templates provide karta hai.
| Option | Name |
| T0 | Paranoid |
| T1 | Sneaky |
| T2 | Polite |
| T3 | Normal |
| T4 | Aggressive |
| T5 | Insane |
Example:
nmap -sS -T4 TARGET_IP
Ye Aggressive speed par scan karega.
Verbose Output
Agar scan progress detail me dekhni ho:
nmap -v TARGET_IP
Aur zyada details ke liye:
nmap -vv TARGET_IP
Debug Mode
Agar troubleshooting karni ho:
nmap -d TARGET_IP
Maximum debugging:
nmap -d9 TARGET_IP
Scan Reports Save Karna
Normal Format
nmap -oN report.txt TARGET_IP
XML Format
nmap -oX report.xml TARGET_IP
Grepable Format
nmap -oG report.gnmap TARGET_IP
All Formats
nmap -oA report TARGET_IP
Ye teen files create karega:
report.nmap
report.xml
report.gnmap
Important Interview Questions
192.168.0.1/27 me Last IP Address Kya Hogi?
/27 subnet me total 32 IP addresses hoti hain.
Range:
192.168.0.0 – 192.168.0.31
Last IP:
192.168.0.31
-T4 Ka Non-Numeric Naam Kya Hai?
Aggressive
Local User Privileges Ke Sath Nmap Ka Default Scan Kaunsa Hota Hai?
TCP Connect Scan (-sT)
Kyuki SYN Scan (-sS) ke liye root privileges required hote hain.
Conclusion
Nmap Cyber Security aur Penetration Testing ki duniya ka sabse important network scanning tool hai. Iski help se hum live hosts discover kar sakte hain, open ports identify kar sakte hain, running services aur unke versions detect kar sakte hain, aur target system ke baare me kaafi valuable information collect kar sakte hain.
Agar aap Ethical Hacking ya Cyber Security seekh rahe hain, to Nmap aapke toolkit ka sabse pehla aur sabse powerful tool hona chahiye.
