The early internet systems administrators realised that they were being attacked frequently. This gave birth to the network firewall. There was a necessity to come up with a process that alerted against sins of attack. The firewall filters out unwanted network traffic and keeps the internal network safe. Firewall often provides protection beyond firewall function such as intrusion detection and maintaining the servers and other devices within the private network secure. However, the main emphasis should not be on the multi-function ability of the firewall. Instead, the focus should be on whether or not it will successfully protect the private network from external threats. Firewall type aside; it’s always advisable to engage in best practices when connected to public Wi-Fi. Best The five different types of firewall are mentioned below:

1. Packet Filtering Firewall –

The packet filtering firewall operates at the junction points where routers perform their function. However, the firewalls do not route packets. Instead, they compare each of the packets received to a set of established criteria. These criteria include the allowed IP addresses, port number, packet type etc. The packets that are tagged as troublesome are dropped and not forwarded.

Circuit-level Gateway

2. Circuit-level Gateway –

The circuit-level gateway is another quick way to identify threats as they monitor TCP handshakes and other network protocol session initiation messages across the network. This firewall is established between the local and remote hosts to determine whether or not the session being initiated is legitimate. The firewall does not inspect the packets.

3. Stateful Inspection Firewall –

The stateful inspection firewall, however, examine each packet. Moreover, it also keeps track of whether or not the packet is a part of an established TCP or any other network session. This offers greater security but also, at the same time exacts a higher toll on the performance of the network. Another variant of the stateful inspection firewall is the multilayer inspection firewall. This firewall takes into account the flow of transaction across multiple layers of the Open Systems Interconnection.

Application-level Gateway

4. Application-level Gateway –

This firewall, sometimes called a proxy firewall, combines some features of the packet filtering firewall and the circuit-level gateway firewall. Apart from filtering packets according to the service they are intended for, they also filter by other characteristics such as HTTP request string.

5. Next-generation Firewall –

A typical next-generation firewall system combines packet inspect with stateful inspection, deep packet inspection and other network security systems such as antivirus, malware filtering, intrusion detection and prevention. A deep packet inspection looks at the data that the packets are carrying.