The name firewall comes from the real-world protection that prevents the fire from penetrating beyond that point. Firewalls are common barriers between attached garages and a house, and between an automotive engine and the passenger compartment.
The widespread use of firewalls begins after the first known Internet worm, the Morris worm. What was intended to be an honest experiment by a college student to see how many computers were attached to the Internet, the Morris worm ended up causing massive denial-of-service attacks?
Estimates of the damage caused the worm range from $10 million to $100 million, but it also showed that Internet service providers at the time were not prepared for the eventuality of such an attack.
Firewalls act as an extra barrier on top of other security measures, such as antivirus software. However, hardware and software firewall systems work in slightly different manners.
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.
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: Blocking off a certain IP address or a range of IP addresses, which you think are predatory.
- Domain names: You can only allow certain specific domain names to access your systems/servers or allow access to only some specified types of domain names or domain name extension like .edu or .mil.
- Protocols: A firewall can decide which of the systems can allow or have access to common protocols like IP, SMTP, FTP, UDP, ICMP, Telnet or SNMP.
- Ports: Blocking or disabling ports of servers that are connected to the internet will help maintain the kind of data flow you want to see it used for & also close down possible entry points for hackers or malignant software.
- Keywords: Firewalls also can sift through the data flow for a match of the keywords or phrases to block out offensive or unwanted data from flowing in.
Hardware firewalls are systems that are independent of the computers they protect that filter the Internet as information passes into a computer. Most broadband Internet routers have their own firewall built in.
In general, hardware firewalls work by examining the data that flows in from the Internet and verifying whether that information is safe. Simple firewalls, known as packet filters, examine the data itself for information such as its location and its source.
These types of firewalls have their benefits for home and small businesses because they require little to no set-up, and multiple nodes (computers) can be protected from patching into the same router.
However, the major drawback to typical home-use hardware firewalls is the fact that they only examine the data that is coming in to a computer, and not the data leaving a computer.
There are two main advantages that software firewalls have over hardware ones. The first is that software firewalls can monitor outgoing data traffic. Not only does this prevent a computer from becoming a bot or a zombie, but also it can prevent computers from broadcasting any other malware, such as worms or computer viruses.
The other advantage is that software firewalls are customizable. These programs can be adjusted to meet the needs of the user, such as if they need permissions to be eased up while they’re online gaming or watching an online video.
However, the main disadvantage to software firewalls is that they only protect one computer. Every computer must have its own licensed firewall product. On the other hand, a hardware firewall can protect every computer attached to it.