What is firewall? and type's of firewall?

Component in the network used to prevent unauthorized access, it could be software or hardware based. the main function of the firewall is to block the unused ports.

firewall is used for protecting from unauthorised users and unnecessary traffic in your network . firewall made you network protected from intruder  and unknow  persons . there are so many firewall according to the leading interconnecting device manufacturer .

CIsco , juniper  in that various are ASA, checkpoint and many more .

-  a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts.

Hope this helps you ....

Firewall is a system designed to prevent unauthorized access to or from a private network. You can implement a firewall in either hardware or software form All messages entering or leaving the intranet (i.e., the local network to which you are connected) must pass through the firewall.

Note: In protecting private information, a firewall is considered a first line of defence; it cannot, however, be considered the only such line. Firewalls are generally designed to protect network traffic and connections, and therefore do not attempt to authenticate individual users when determining who can access a particular computer or network.

Types of firewalls

      àNetwork layer

      àApplication layer

      àProxy

      àUTM

      àPacket filtering:

      àCircuit-level gateway implementation

      àWeb application firewall

firewall software/hardware used to block unauthorized access to your network. the hardware firewall better than software.

 Firewall is used to prevent the unauthorized access to your network or computers.

Most popular firewall in Cisco is ASA series firewalls and in Juniper is Netscreen firewall.

A firewall is a hardware or software system that prevents unauthorized access to or from a network. They can be implemented in both hardware and software, or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks connected to the Internet. All data entering or leaving the Intranet pass through the firewall, which examines each packet and blocks those that do not meet the specified security criteria.

firewall is used to filters the network traffic ..

Two Types hardware based and software based

A firewall is used to block unauthorized access to our network it could be software or hardware based

Firewall is essentially a filter. It is either a software program or hardware device used in computer systems to prohibit forbidden information for passing though, while allowing approved information. The communication which the firewall prevents from passing though could be hackers trying to gain access to your personal information stored on your computer. 

types of firewall are 

Network layer or packet filters

Application-layer

Proxies

Network address translation

Firewall - This can prevent unauthorized access between the networks, it can be software or hardware device .

Type of firewall:

1.     Packet filtering

2.     Stateful  inspection

3.     Application layer firewall