Many types of firewall in network security protect our computers from Internet hackers. Internet hackers can steal our bank details from our computers and can reduce our bank balance from thousands of dollars to zero within seconds. So firewall is must in a computer or in a computer network.
What are the types of firewall in network security ?
There are three types of firewall in network security:
- Packet filtering firewall
- Application or proxy firewall
- Hybrid firewall
Before starting with types of firewall in network security you should know what are data packets?? When we want to download a file of size say 200 MB from internet then we will not receive the entire 200 MB data at once but we will receive small packet say 5 MB every second. Some of the part of this 5 MB packet is occupied with information like which computer is sending the data, which computer is receiving the data etc.. The remaining portion of this 5 MB packet contains the part of the actual data that we want to download so part of the actual data plus some information together forms a data packet or IP packets and this part of actual data is called payload.
Now we can start with firewall types:
Packet filtering firewall: Suppose I am downloading a file from Internet when the data packet arrives, a packet filtering firewalls it only checks the senders and the receivers IP address and the port number present in the data packet. The rules written in a list are called access control list are used for data packet verification. If everything is OK then the data packet is allowed to pass through packet filtering firewalls and then to my computer but what is port number?? Actually these are some digits written after IP address separated with a colon and are used for the successful data packet transfer. The packet filtering firewall is already present in Internet routers so they are the cheapest and the quickest way to implement. The only limitation of packet filtering firewall is that it does not checks the data portion that is payload of the data packets so a hacker could send some malicious data tagged in this payload section. Hence, packet filtering firewalls provides no security.
Application or proxy firewall: Let us understand it with an example. Suppose your mother asked you to buy a pen from the market. You go to the shop, buy the pen, come home back and give the pen to your mother. Here you have done the work that your mother wanted you to do without letting the shopkeeper knew who actually wanted that pen. Same is the case with application of proxy firewall. Replace the shopkeeper with Internet, your mother with personal computer and yourself with proxy firewall. Like you did not let the shop keeper knew that your mother was the one who actually wanted that pen. Similarly, proxy firewalls do not let the Internet know which computer actually wants to visit the requested website that is proxy firewalls hide us from attackers in Internet.
Let us understand this whole process. User enters the website www.facebook.com in the web browser. Proxy firewalls receives the request and forwards that request to internet. The web server in Internet receives the request and response back to the proxy firewalls with the requested information. The proxy firewalls receives the information and forwards it to the original client for his viewing pleasure. In this whole process web server thinks that proxy firewall is the one who wants to visit www.facebook.com that is proxy firewalls do not let the web server know the origin of the request. So proxy firewalls protect us from the potential attackers in Internet by not disclosing our computers identity but I should say by not disclosing our computer’s IP address. Since application firewalls also checks the payload of the received data package. So they are generally much slower than the packet filtering firewalls.
Hybrid firewall: It combines packet filtering firewalls and application firewalls in series to enhance the security. If they are connected in parallel then the security of the connection will be reduced to the parameters defined by packet filtering firewalls that is Application Firewall will be of no use if the two firewalls are connected in parallel. For this reason hybrid firewall use packet filtering and application firewalls in series. As a result hybrid firewalls provide best security compared to packet filtering and application firewalls.
Now which types of firewall in network security will be best for us will depend on its implementation environment. For example, packet filtering firewalls will be best for low risk environments like florist shop, application Firewall will be best for medium risk environment like universities and hybrid firewalls will be best for high risk environments like hospitals whose database contains important reports of the patient. Now you can choose a firewall as per your needs.