What is a firewall? A firewall is an application designed to control network traffic to and from a computer or network, permitting or denying communication based on a set of rules.
How to configure a firewall Lets go to Start, Control Panel, Security Center, Windows Firewall. The new window has three tabs: General, Exceptions and Advanced Options. The General tab shows the Firewall actual state and let us enable or disable it. By disabling it we are allowing all the inbound and outbound communication, but by enabling it (recommended), every connection will be blocked by default and the only connections allowed will be the ones listed in the permitted list. This list is in the Exceptions tab and is editable. If for any reason we want to block all the traffic, we can mark “Not Exceptions allowed” and we will be closing the access on both sides. 
Configuring a firewall is a task for the application, the program by itself cannot do anything. We will have to indicate always to block or allow the connections. Normally, when a program tries to access the communications of the system, the Firewall intercepts the petition and stops partially the access, shows a warning to the user asking for approval. Depending on the action, a rule is created to fix the behavior from now on. If the access is approved, the rule is included in the list of exceptions. Adding Exceptions We can manually include, erase or modify the exceptions in this list. If we need any application access the network, we can click on the Add Program button… and select the executable file of the program. Other possibility is to enable the TCP or UDP port the application requires, indicating by a label what is the name appearing in the list. 
There is a button to establish the scope of action of the rule, were we can decide if is only for the access to Internet (public network), local network (private network) or to the list of addresses or segments of the specified addresses. By marking the verification of an item of the list, we are applying or not the exception. Advanced Options In this tab we can configure options for every connection of the system. Here we have three sections. In the first one, we can select a connection of the system and configure the specific exceptions for the applications and services of the system. In the second section we can create a registry to control the Firewall and solve different problems. And in the last one we can configure the ICMP (Internet Control of Messages Protocol), typically used for the exchange of errors. 
Second Part
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