Firewall

 

A firewall is a network security device, either hardware or software-based, which monitors all incoming and outgoing traffic and based on a defined set of security rules it accepts, rejects or drops that specific traffic.    Accept : allow the traffic Reject : block the traffic but reply with an “unreachable error” Drop : block the traffic with no reply A firewall establishes a barrier between secured internal networks and outside untrusted network, such as the Internet.