What is a Firewall?
Table of Contents
Firewall is the system that provides security by monitoring the incoming and outgoing traffic bound by a set of rules. These rules are also known as ACL’s(Access Control Lists).
What are ACL’s(Access Control Lists)?
Access Control Lists are the rules that are applied at the router interfaces and upon checking, they grant or deny the traffic as per defined rules.
There are different sets of criteria while defining these rules that includes:-
Firewalls can be both software and hardware:-
What are Software Firewalls?
The software firewalls are the security systems that we normally find in our computers and they give security to client systems. These firewalls gives protection from outside intrusions locally. These are more vulnerable and are more economical.
What are Hardware Firewalls?
These are physical security devices and are to be configured according to the requirements. These firewalls monitor network traffic and port security but are more costly.
There are different types of Firewalls and most important are:-
Types of Firewalls:-
Packet Filtering Firewalls:-
In Packet Filtering, the security system drops the packets after evaluating individual packets and if the specific defined rules are not met.
The packet header is used to allow/deny the packet by considering :-
- Source–> IP address, Port Number
- Destination–> IP address, Port Number
- Protocol–> Type of protocol Used
Application Level Firewalls:-
These firewalls works will monitor the traffic at application layer and decide the entry/deny of the packet by depending on the information they have in the application protocol.
Stateful firewalls:-
These firewalls filters the traffic in a whole session depending on the information in the IP header. In an active session, if the firewall accepts a traffic from a particular IP headers and is added into its table, then it can come into the network without any problems even though its a bad traffic. This type of firewall is more prone to attacks.
