Packet filtering firewalls work online at intersections where equipment like routers and switches operate. These firewalls don’t route packets; instead, they check each one against a list of predetermined standards such as the permitted IP addresses, packet type, port number, and other information from the packet protocol headers. Generally speaking, complex packets are unceremoniously dropped, which means they are not transmitted and eventually vanish from existence. Even though packet filtering is a cheap firewall, it may not always offer the level of security required for all use cases. Packet filtering provides a fundamental security level that can protect against known threats for small or budget-constrained businesses. Larger organizations can additionally use packet filtering as a layer of defense to sift through internal departmental communication for potentially hazardous content.