What is Network Monitoring? – Basic Concepts and Fundamentals

In most networks, data packets must first pass through a firewall. It’s purpose is to keep bad traffic out and keep the private network secure. A firewall does this by filtering traffic between the internet and private network. When an incoming
data packet is flagged by firewall rules, it is blocked from the private network.

Firewalls also control user access between the internet and the private network. For instance, a firewall can be configured to prevent users on the private network from using specific protocols such as peer to peer. This is one way that Firewalls secure
private networks from unauthorized access, malware and other security threats.

Data packets passed through the firewall are received by a switch on the private network. Switches connect laptops, servers, printers and other devices to the private network. These devices are connected to the switch using a Network Interface Card, or
NIC for short. Each NIC has a unique Media Access Control, or MAC address. Switches transmit data between devices using these MAC addresses.