Understand Firewall

फ़ायरवॉल kya hai :

Computer Networks मे firewall एक hardware or software based network security system है जो की कुछ set of rules and policies के base पर incoming और outgoing network traffic को monitor and control करता है | firewall को basically किसी भी computer system or network को safe करने के लिए ही design किया गया है | कोई भी firewall use करे चाहे software or hardware दोनों का काम unauthorized access को monitor करना ऐवम रोकना ही होता है |

How फ़ायरवॉल works : – Generally Network फ़ायरवॉल को किसी भी private network के अंदर लगाया जाता है and जब भी कोई network user, internet का data (outside network) access करने की request करता है तो request फ़ायरवॉल के पास होती हुई जाती है | फ़ायरवॉल कोई भी internal user और outside user की request को check करने का काम करता है | एक बार फ़ायरवॉल के पास जब request आती है तो ये अपने rules से उनको verify करने के बाद information को access or block कर देता है (based on valid or invalid request)|

इस प्रकार सभी incoming or outgoing request को फ़ायरवॉल से पास होना होता है and फ़ायरवॉल सभी network packets को examine करके security criteria or rules से verify करता है और फ़ायरवॉल पालिसी के base पर access or deny करता है | इससे हम यह कह सकते है की firewall ऐसे software or hardware device है जिसकी help से illegal access को block किया जा सकता है ऐवम hackers, viruses, and worms से आपके network system को safe रखा जा सकता है |

Firewall History : फ़ायरवॉल का नाम आग को रोकने के लिए बनायीं गयी दिवार से लिया गया है | जब 1980 मे कंप्यूटर्स एंड नेटवर्क स्टार्ट हुआ तो कुछ समय बाद सिक्योरिटी की जरुरत महसूस की जाने लगी तब ACL ki हेल्प से network security और पैकेट allow or drop किये जाने लगे | ACL (access control list) जो की राऊटर मे maintain होने वाली list थी, बताती थी की कौनसे IP address को network मे permission देनी है and किस को नहीं देनी लेकिन जैसे जैसे computers and network की growth शुरू हुई ACL से ये सब maintain किया जाना मुश्किल होता गया | 1992 मे Digital Equipment Corp firewall की जरुरत को समझते हुए पहली commercial firewall जिसका नाम था DEC SEAL बनायीं और उसके बाद तो firewall technology मे बहुत बदलाव आये ऐवम नेटवर्क ऐवम सेक्युर्टी की जरुरत की according मॉडल्स आने शुरू हुए |

An Introduction to Firewalls

Introduction

Firewalls are computer security systems that protect your office/home PCs or your network from intruders, hackers & malicious code. Firewalls protect you from offensive software that may come to reside on your systems or from prying hackers. In a day and age when online security concerns are the top priority of the computer users, Firewalls provide you with the necessary safety and protection.

What exactly are firewalls?

Firewalls are software programs or hardware devices that filter the traffic that flows into you PC or your network through a internet connection. They sift through the data flow & block that which they deem (based on how & for what you have tuned the firewall) harmful to your network or computer system.

When connected to the internet, even a standalone PC or a network of interconnected computers make easy targets for malicious software & unscrupulous hackers. A firewall can offer the security that makes you less vulnerable and also protect your data from being compromised or your computers being taken hostage.

How do they work?

Firewalls are setup at every connection to the Internet, therefore subjecting all data flow to careful monitoring. Firewalls can also be tuned to follow "rules". These Rules are simply security rules that can be set up by yourself or by the network administrators to allow traffic to their web servers, FTP servers, Telnet servers, thereby giving the computer owners/administrators immense control over the traffic that flows in & out of their systems or networks.

Rules will decide who can connect to the internet, what kind of connections can be made, which or what kind of files can be transmitted in out. Basically all traffic in & out can be watched and controlled thus giving the firewall installer a high level of security & protection.

Firewall logic

Firewalls use 3 types of filtering mechanisms:

• Packet filtering or packet purity
• Data flow consists of packets of information and firewalls analyze these packets to sniff out offensive or unwanted packets depending on what you have defined as unwanted packets.
• Proxy
• Firewalls in this case assume the role of a recipient & in turn sends it to the node that has requested the information & vice versa.
• Inspection
• In this case Firewalls instead of sifting through all of the information in the packets, mark key features in all outgoing requests & check for the same matching characteristics in the inflow to decide if it relevant information that is coming through.

Firewall Rules

Firewalls rules can be customized as per your needs, requirements & security threat levels. You can create or disable firewall filter rules based on such conditions as:

• IP Addresses
• Blocking off a certain IP address or a range of IP addresses, which you think are predatory. What is my IP address? Where is an IP address located?
• Domain names
• You can only allow certain specific domain names to access your systems/servers or allow access to only some specified types of domain names or domain name extension like .edu or .mil.
• Protocols
• A firewall can decide which of the systems can allow or have access to common protocols like IP, SMTP, FTP, UDP,ICMP,Telnet or SNMP.
• Ports
• Blocking or disabling ports of servers that are connected to the internet will help maintain the kind of data flow you want to see it used for & also close down possible entry points for hackers or malignant software.
• Keywords
• Firewalls also can sift through the data flow for a match of the keywords or phrases to block out offensive or unwanted data from flowing in.

Types of Firewall

• Software firewalls
• New generation Operating systems come with built in firewalls or you can buy a firewall software for the computer that accesses the internet or acts as the gateway to your home network.
• Hardware firewalls
• Hardware firewalls are usually routers with a built in Ethernet card and hub. Your computer or computers on your network connect to this router & access the web.

Summary

Firewalls are a must have for any kind of computer usage that go online. They protect you from all kinds of abuse & unauthorised access like trojans that allow taking control of your computers by remote logins or backdoors, virus or use your resources to launch DOS attacks.

Firewalls are worth installing. Be it a basic standalone system, a home network or a office network, all face varying levels of risks & Firewalls do a good job in mitigating these risks. Tune the firewall for your requirements & security levels and you have one reason less to worry.

Some of the firewall products that you may want to check out are:

• McAfee Internet Security
• Microsoft Windows Firewall
• Norton Personal Firewall
• Trend Micro PC-cillin
• ZoneAlarm Security Suit

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