1. Packet filtering ek technique hoti hai jo network access ko control karne ke liye use ki jaati hai. Is technique ke zariye outgoing aur incoming packets ko monitor kiya jata hai, aur unhe source aur destination IP addresses, protocols, aur ports ke basis par pass ya halt kiya jata hai.

Packet filtering firewall ko static firewall bhi kaha jata hai, kyunki yeh predefined rules ke basis par kaam karta hai, aur traffic ko evaluate karke allow ya block karta hai. Is type ka firewall simple aur efficient hota hai, lekin yeh complex attacks ya deeper analysis jaise features nahi provide karta, jaise application layer filtering. Yeh primarily network layer par kaam karta hai aur packet-level security provide karta hai.

2. Stateful inspection firewalls, jo dynamic packet filtering bhi kehlate hain, ek advanced type of packet filtering hote hain jo data packets ko firewall ke through move karte waqt closely monitor karte hain. In firewalls ka main feature yeh hai ki yeh yeh check karte hain ki packet kisi particular session ka part hai ya nahi.

Agar packet kisi established session ka part hota hai, toh firewall us communication ko permit karta hai. Agar session properly established nahi hai, toh communication block kar diya jata hai. Iska matlab yeh hai ki stateful inspection firewall sirf valid aur trusted sessions ko allow karta hai, aur yeh ensure karta hai ki unauthorized ya suspicious packets network me enter na karein. Yeh firewall traffic ko analyze karta hai aur connection ke state ko track karta hai, jo ki packet filtering se zyada intelligent aur secure hota hai.

3. Application layer firewalls, jo OSI model ke application layer ki information ko examine karte hain, network security ka ek advanced form hai. Yeh firewalls application-specific protocols, jaise HTTP requests, ko inspect karte hain aur unmein koi suspicious activity ya harmful application ko identify karte hain.

Agar firewall ko lagta hai ki koi application network ko harm kar sakti hai ya wo secure nahi hai, toh wo us communication ko immediately block kar deta hai. Application layer firewalls detailed analysis karte hain aur data ko application level tak inspect karte hain, jaise ki web traffic, email protocols, etc. Is tarah se yeh firewall network ko not only packet level, balki application level par bhi protect karta hai, jo ki zyada effective aur targeted security provide karta hai.

4. Next-generation firewalls (NGFW) ko intelligent firewalls bhi kaha jata hai. Yeh firewalls un sabhi tasks ko perform karte hain jo humne pehle ke firewall types, jaise packet filtering, stateful inspection, aur application layer filtering, se seekhe hain, lekin unme kuch additional features bhi hote hain jo unhe zyada powerful aur advanced banate hain.

Next-generation firewalls me application awareness aur control hota hai, jo unhe applications ko identify karne aur unke upar control rakhne ki ability deta hai. Iske alawa, inme integrated intrusion prevention systems (IPS) bhi hoti hain jo real-time me suspicious activities ko detect aur block karte hain. NGFWs me cloud-delivered threat intelligence bhi hoti hai, jo constantly update hoti hai aur naye threats ke against firewall ko protect karne me madad karti hai.

Yeh firewalls zyadatar modern enterprises aur complex networks me use kiye jate hain, jahan high-level security aur detailed monitoring ki zarurat hoti hai.

5. Circuit-level gateway ek type ka firewall hota hai jo UDP (User Datagram Protocol) aur TCP (Transmission Control Protocol) connections ki security provide karta hai. Ye firewall OSI (Open Systems Interconnection) network model ke transport aur application layers ke beech kaam karta hai, jaise ki session layer. Iska kaam yeh hota hai ki ye data connections ko monitor karta hai aur ensure karta hai ki valid connections hi network par aaye, unauthorized access ko rokta hai.

Is gateway ka use zyada tar secure communication setup karne ke liye hota hai, jahan pe data packets ki authenticity ko verify karke network ke andar ki connections ko manage kiya jata hai.

6. Software firewall ek aisa computer software hota hai jo humare system par run karta hai. Yeh firewall humare system ko external attacks se bachata hai, jaise ki unauthorized access, malicious attacks, aur dusre cyber threats. Jab bhi koi risk ho, jaise kisi insecure website ko open karna ya koi suspicious email kholna, yeh firewall hume alert karta hai aur hume potential danger ke baare mein batata hai.

Software firewall system ki internal security ko protect karta hai aur data packets ko monitor karke ensure karta hai ki sirf authorized aur safe connections hi pass hon. Yeh ek layer of defense hoti hai jo humare system ko cyber threats se safe rakhti hai.

7. Hardware firewall ek physical device hota hai jo network boundary ko enforce karne ke liye deploy kiya jata hai. Jab bhi koi network link is boundary ko cross karta hai, wo firewall ke through pass hota hai, jisse firewall ko inbound aur outbound traffic ka inspection karne ka mauka milta hai. Iska main kaam access controls aur security policies ko enforce karna hota hai, taaki unauthorized access aur potential threats ko rokha ja sake.

Hardware firewall typically ek dedicated device hota hai jo network ka traffic monitor karta hai aur security rules ko apply karta hai. Yeh firewall high-performance security provide karta hai, especially large networks mein, jahan pe heavy traffic hota hai aur multiple devices ko protect karna hota hai.

8. Cloud firewall ek software-based firewall hota hai jo cloud mein deploy kiya jata hai aur private network ko unwanted access se protect karta hai. Yeh traditional firewalls se different hota hai, kyunki yeh cloud level par data ko filter karta hai, na ki physical devices par.

Cloud firewall ki wajah se organizations ko flexibility aur scalability milti hai, kyunki yeh cloud-based networks ko easily secure kar sakte hain bina physical hardware ke. Yeh firewall cloud environment mein hone wale traffic ko monitor karta hai aur unauthorized access, malicious attacks, aur other security risks ko block karta hai.

Iska fayda yeh hota hai ki, agar aapka network cloud pe hai, toh cloud firewall directly aapke cloud services ke saath integrated hota hai, jo network ko dynamically secure karta hai.

9. WAF (Web Application Firewall) ek specialized firewall hota hai jo web applications ko protect karta hai. Yeh   firewall HTTP aur HTTPS traffic ko filter karta hai aur web applications ko common attacks jaise SQL injection, Cross-Site Scripting (XSS), Cross-Site Request Forgery (CSRF), aur other vulnerabilities se bachata hai.

WAF ka kaam yeh hota hai ki wo incoming web traffic ko analyze karke malicious requests ko detect aur block kare, jisse web application ki security badhti hai. Yeh firewall application layer pe kaam karta hai, aur web-based attacks ko specifically target karta hai jo traditional firewalls detect nahi kar paate.

WAF ko mostly cloud-based or on-premises environments me use kiya jata hai, aur yeh business websites, online services, aur web applications ke liye essential security layer hoti hai. Iske zariye website owners apne applications ko hackers aur malicious bots se protect kar sakte hain.