What is a firewall? Briefly explain different firewall techniques.

Q. What is a firewall? Briefly explain different firewall techniques.

Answer =

The system designed to prevent unauthorized access to or from a private network is called Firewall.

There are several types of firewall techniques:-

• Packet filter:- Looks as each packet entering or leaving the network and accepts or rejects it based on user-defined rules. Packet filtering is fairly effective and transparent to users, but it is difficult to configure. In addition, it is susceptible to IP spoofing.
• Application gateway:- Applies security mechanisms to specific applications, such as FTP and Telnet servers. This is very effective, but can impose a performance degradation.
• Proxy server:- Intercepts all messages entering and leaving the network. The proxy server effectively hides the true network addresses.
• Circuit-level gateway:- Applies security mechanisms when a connection is established. Once the connection has been made, packets can flow between the hosts without further checking.