It is commonly known that Firewall is an imperative protection provided to PCs. This application is between the system and other network which controls the outgoing and incoming network traffic. It would depend on the rules of firewall as to which traffic is allowed and which is not.
Most people use routers at home in order to share internet connection between several devices. A system that is connected directly to the internet would have a public IP. So any netizen can reach it. Any network services that are running on the computer like that which comes with Windows for printer sharing and file, remote desktop would be accessible by the netizen.
Microsoft had introduced Firewall in Windows XP Service Pack 2, and it finally enabled a by default firewall in Windows. A firewall would obviously drop all incoming connections unless it has been specifically configured to allow incoming connections.
This would not allow people on the Internet from connecting to local network services on your system. It even controls access to the network services from other computers on local network. This is why user is asked as to what type of network it is when connected to Windows. If connected to home network the firewall provides access to these services. If it is connected to public network, the access would be denied by the firewall.
In case a network service is configured that no net connection would be allowed, there is a possibility that the services has security lapse and customized request would allow the attacker to run some code on the system. This would be prevented by the firewall thereby preventing the incoming connections from reaching these susceptible services.
Firewalls sit between a network say the Internet and the computer but it is protecting. Its main purpose for home users is blocking unnecessary incoming network traffic. It can also analyze the traffic that leaves or reaches the network as well as decides what can be done with it. Say for instance, a firewall could b configured in order to block some types of outgoing or suspicious traffic or even all transfer.
A firewall does have certain rules which denies as well as allows certain types of traffic. Say for instance it could allow connections to the server from specific IP address thereby dropping all link requests from somewhere else for safety.
Firewalls run in the laptop. It can also be a out-and-out hardware used for a corporate network. Corporate firewalls could examine outgoing traffic thereby ensuring that no malware was communicating through the network or observe employee’s network use as well as filter traffic. One can configure a firewall to only allow web browsing traffic and other applications.