Firewall:A firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules.Firewalls can be either hardware or software, but the ideal configuration will consist of both.In addition to limiting access to your computer and network, a firewall is also useful for allowing remote access to a private network through secure authentication certificates and logins.It screens traffic going into or out of an organization. It filters all incoming packets destined for a specific host. It is a packet filter firewall or proxy-based firewall, i.e.it protects and secures the inside network from any outside network.