Primer

Firewalls are software programs or hardware devices that filter the traffic that flows into you PC or your network through an internet connection. They sift through the data flow & block that which they deem (based on how & for what you have tuned the firewall) harmful to your network or computer system.

How do they work?

Firewalls are setup at every connection to the Internet, therefore subjecting all data flow to careful monitoring. Firewalls can also be tuned to follow "rules". These Rules are simply security rules that can be set up by yourself or by the network administrators to allow traffic to their web servers, FTP servers, Telnet servers, thereby giving the computer owners/administrators immense control over the traffic that flows in & out of their systems or networks.

Rules will decide who can connect to the internet, what kind of connections can be made, which or what kind of files can be transmitted in out. Basically all traffic in & out can be watched and controlled thus giving the firewall installer a high level of security & protection.

Firewalls use 3 types of filtering mechanisms:

Packet filtering or packet purity

Data flow consists of packets of information and firewalls analyze these packets to sniff out offensive or unwanted packets depending on what you have defined as unwanted packets.

Proxy

Firewalls in this case assume the role of a recipient & in turn sends it to the node that has requested the information & vice versa.

Inspection

In this case Firewalls instead of sifting through all of the information in the packets, mark key features in all outgoing requests & check for the same matching characteristics in the inflow to decide if it relevant information that is coming through.

Firewall Rules

Firewalls rules can be customized as per your needs, requirements & security threat levels. You can create or disable firewall filter rules based on such conditions as:

IP Addresses...