Author : Purvil
A firewall is a device which is used to control the flow of traffic into and out-of network. In other words, it is a security device which installed between two networks, internal network to outside network (more often the internet).
Based on the rule define in the firewall data will be passed to one network to other network.
The primary job of a firewall is to secure the inside network from the internet.
Systems on one side of the firewall are protected from systems on the other side.
Consider LAN is corporate or our campus network and WAN is internet.
If we place firewall between the two networks then it will control the flow of the whole traffic and based on rule define into firewall.
It will allow or deny the traffic.Firewalls generally filter traffic based on two methodologies:
Firewalls generally filter traffic based on two methodologies:
A firewall can allow any traffic except what is specified as restricted part. It depends on the type of firewall used, the source, the destination addresses, and the ports.
A firewall can deny any traffic that does not meet the specific criteria based on the network layer on which the firewall operates.
Firewall is the first destination for the traffic coming to your internal network.
So, anything which comes to your internal network passes through the firewall and any outgoing traffic will also pass through the firewall before leaving your network completely.
This is the reason that sometimes this type of firewall filter is also called screening routers.
Firewall types the way a firewall provides greater protection relies on the firewall itself, and on the policies that are configured on it.
The Following types of firewall are:
Stateful Packet-Inspection (SPI)