Network Firewall
A Network Firewall is a system or group of systems used to control access between two networks – a trusted and an untrusted network A firewall is considered a first line of defense in protecting private information. Need of firewall: If a user spend a lot of time on the internet and is not behind a firewall then the system can be easily attacked. Therefore, protection between user and the internet is probably the most important thing that one needs to have (after getting virus checking software and performing regular backups). For those with a DSL, cable modem or other "always-on" connection, user must get a firewall. This is critical, as machine is always live and it most likely has a fixed IP address. This makes it easier for system to be "found" and attacked. Unprotected system using a DSL modem : As we can see, someone on the internet can attack the computer system easily as the DSL modem provides no protection (some DSL modems have built-in