Understanding Packet Filtering Firewalls In Network Security
In my previous article, I have talked about some of the facts that you need to know about Denial Of Service attacks in network security. In this article, I want to talk about an important firewall concept that you need to know. It is packet filtering firewalls. Follow me as we will at this together in this article.
Packet filtering firewalls in network security are the simplest and often the least expensive type of firewalls. Several other types of firewall offer there own distinct advantages. Here are some of them: packet filtering, application gateway, circuit-level gateway and stateful packet inspection among others.
And now…
The packet filtering firewall is the most basic type of firewall. In a packet filtering firewall, each incoming packet is examined. Only those packet that matched the criteria you set are allowed through. Many operating systems such as Windows clients, such as Windows 8 and 10 and many Linux distributions including basic packet filtering software with the operating systems.
Packet filtering firewalls are also referred to as screening firewalls. They can filter packets based on packet size, the protocol used, source IP address, and many other parameters. Some routers offer this type of firewall protection in addition to there normal routing functions.
Packet filtering firewalls work by examining a packet’s source address, a destination address, source port, destination port, and protocol type. Based o these factors and the rules that the firewall has been configured to use, they either allow or deny passage to the packet.
These firewalls are very easy to configure and inexpensive. Some operating systems, such as Windows 10 and Linux, include built-in packet filtering capabilities.
There are a few disadvantages of packet filtering firewalls. One disadvantage is that they do not actually examine the packet or compare it to previous packets, therefore, they are quite susceptible to either a ping flood or SYN flood. They also do not offer any user authentication. Because this type of firewall looks only at the packet needed for information, it has no information about the packet contents.
It also does not track packets, so it has no information about the preceding packets. Therefore if thousands of packets coming from the same IP address in a short period of time, a host would not notice that this pattern often indicates that the IP address in question is attempting to perform a DoS attack on the network.
To configure a packet filtering firewall, simply establish appropriate filtering rules. A set of rules for a given firewall would need to cover the following:
- What type of protocol to allow (FTP, SMTP, POP3 among others).
- What source port to allow.
- What destination port to allow. You can always block IP addresses if you wish.
These rules will allow the firewall to determine what traffic to allow in and what traffic to block. Because this sport of firewall use only very limited system resources, it is relatively easy to configure and can be obtained even for free. Although it is not the most secure type of firewall, you are likely to encounter it frequently.
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