What are the different types of firewalls?

Firewalls are security tools that help to implement access control policy on applications and networks. This protects a network from malicious attackers.

There are basically three types of firewalls, which are discussed below:

Network layer firewall/ packet filtering firewall

A router is a good example of a network firewall. It has the ability to observe a network packet header and access the information contained therein. The observed information is then filtered by a certain filter policy like the source IP-address, the source port of the packet, the destination IP-address of the packet, or the destination port address of the packet.

A router also observes the protocol used in sending the data packet, either a transmission control protocol or a user data-gram protocol. This kind of firewall is easy to set up, as it is in-built in most devices and anyone can activate it easily.

This firewall works with an access control list where these policies are kept so that the boxes are unchecked for the packet to gain access into the network. However, this firewall is unable to check the database portion of this data packet, which an attacker could take advantage of and manipulate, or steal data from the database. This makes this firewall type a little less secure.

Application firewall

Application layer firewalls are like proxy servers because they do not allow a packet direct access to a user computer network.

Application firewalls can work as network address translators because the packet passing through the network moves from one end to the opposite end. So, when a packet passes through an application, it is possible to conceal the source from which the connection stems from.

After installation of an application firewall on a user computer, this software can perform a network address translation locally on the user computer.

When the firewall tries to deny flow of traffic in and out of the user end, it will deny traffic from all local ports. Every local IP address will be unable to send packets to any remote IP address. This hinders traffic flow in and out of the computer of the user.

But, an application firewall can be installed in which the user permits the flow of traffic through and out of the firewall. The firewall creates a filter rule pattern upon the very first permission granted by the user. From time to time, the user can access the remote networks through this channel. This firewall set-up is not so easy, as it requires some technical knowledge for one to be able to set up the firewall.

Hybrid firewall

A hybrid firewall is a combination of the network and the application firewall together as one. This firewall provides a solid protection from malicious codes.

It is mostly useful for educational institutes, banking systems, hospitals, and some industries. Hybrid firewalls enhance security by applying the network layer firewall and the application layer firewall in series.