Introduction Firewall in Network

Introduction Firewall in Network and How Does It Work?

Firewall is used to protect computer networks from unauthorized access. Firewalls serve protect an internal network from external attacks. It prevents malicious access from outside to the computer network. A firewall can grant limited access to outside users network.The firewall two types available hardware and software program configuration. The Firewall also helps to prevent worms, viruses, etc. All messages the intranet must pass through the firewall, which examines each blocks and message those that do not meet the specified security criteria.


Firewall work :-

A Firewall analyses and scan the network traffic and filters .the unsecured and suspicious networks cannot attack the system. Firewall in allow or deny rules set user wise,port forwording,web filtering and bandwidth set etc.

Different types of firewall

(1) Packet filtering :
  • Packet filtering in creates a checkpoint at the traffic router.Only the secure and verified IP address and networks are allowed data and accepts or rejects it based on user-defined rules.
  • The data packets are not verified, i.e. the information and data is not opened at the Firewall stage.
  • They are easy to use and do not overload the device and do not affect its processing speed.
  • Packet filtering is fairly effective and transparent to users

(2) Circuit-Level Gateway Firewall :
  • Circuit-Level Gateway Firewall applies security mechanisms when a UDP or TCP connection is established.
  • Once connection has been made, packets can flow between the hosts without further checking.
  • Circuit-Level Gateway firewall operate on layer 4 and it is also known proxy server.
  • Strong processors and Memory are required for using this Firewall

(3) Statefull Inspection Firewall :
  • Statefull Inspection Firewall allow or block traffic. such as specific packet protocols, IP addresses and ports.these firewalls also uniquely track and filter based on the state of connections using a state table.
  • This firewall in updates filtering rules based on past connection events logged in the state table by the screening router.
  • They are less straining computer resources and bit slow comparison to other Firewalls.

(4) Proxy Server Firewall :
  • Proxy Server are gateway hides and true network address of the computer network connecting.
  • A proxy server connects to the internet, makes the requests for pages connections to servers, etc.and receives the data on behalf of the computer behind it.
  • Proxy Firewalls, also known as application-level firewalls (layer 7) and This firewalls configured to protect a private network.
  • proxy can be configured to allow only certain types of traffic to pass (HTTP files, or web pages).
  • A proxy server has network performanace , analyze and manipulate traffic passing through it.

(5) Next Generation Firewall :
  • The recently launched Firewall systems are known Next-Gen Firewalls
  • Next Generation Firewall IN data packets are thoroughly checked before being passed on to the destination address
  • It is used businesses and sophisticated networks, they provide a holistic solution to filtering out dangers and advanced malware.
  • These are use modern technology for automatic detection of errors , upgradation and network safety.

Where Uses of Firewall ?
  •  Firewall uses Windows and macOS,linux firewalls are built into the operating system.
  • Third-party firewall such as Norton Personal Firewall, Tiny, Black Ice Protection, and McAfee Personal Firewall and Sonicwall ,Cisco Firewall etc. Many of these free versions available.
  • Many home and small office broadband routers have rudimentary firewall capabilities built in.

Sonicwall Firewall Basic Configuration available these link :-


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