Firewall is the system designed for preventing the unauthorized access from or to any private network. The firewall can be implemented on software as well as hardware. There are several private networks that are connected to the internet and intranets. A firewall is used for preventing the users from accessing such networks.
The firewall protects the network allowing the intranet to screen all the messages that enter or leave through the system. There are a set of criteria, which if not matched will disable the unauthorized internet users to access internet or intranet. For security reasons firewall is used during Computer Networking .
There are many firewall techniques such as:
- Application gateway firewall: Through this system, specific applications like FTP and Telnet servers can apply security mechanism.
- Packet filters firewall: There are a set of user defined rule in this system. Every packet entering or leaving the network, the packet filters accepts or rejects them if they do not match the set rules.
- Proxy server firewall: Through this the network address could be hidden. The proxy server captures all messages entering and leaving the network.
- Circuit-level gateway firewall: While establishing a TCP or UDP connection the circuit level gateway applies a security mechanism.
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Firewall is absolutely necessary for protecting private information from the unauthorized users. It helps maintain a greater security of the network and the data and files stored in the system. The firewall can permit, deny or proxy data connections based on the firewall policies of the owner.
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