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Firewalls Transcription

Welcome to our firewalls module. Firewalls are designed to enforce your company's network security policy and protect your network. Firewalls can be either software or hardware based, but they're typically a hardware appliance that are used in your networking infrastructure. Firewalls are usually placed at the perimeter of your network to restrict traffic from entering and exiting the network in violation of your policies.

There are also host-based firewalls which run on a system such as a laptop or desktop computer. These firewalls are designed to protect from other computers on the local area network. And are generally a software program or part of the operating system, and firewalls are considered an access control mechanism which are designed to filter traffic.

Our most basic type of firewall is an IP or Internet protocol packet filtering firewall, which uses an access control list to decide whether traffic should be permitted or denied. They have the ability to filter traffic and block it or forward traffic to its intended destination, depending on whether or not the traffic is permitted by the access control lists.

It makes these decisions by looking at the source IP address and destination IP address, as well as the port numbers contained in the packet headers. These devices can also look at the protocol in use and determine whether or not it is permitted. Once the firewall reviews the traffic, it makes a decision to either forward the traffic on or block it.

Static packet filtering firewalls are a very simple and easy method to stop unwanted incoming traffic. It can look at the header in the packet to determine whether the IP address, ports, or type of protocol are permitted based on the access control list. These devices provide a minimum level of security for low risk environments.

Screening routers provide this technology by using access control lists to determine whether to accept or reject traffic. These devices are pretty simple and do not maintain state information like stateful firewalls, which we'll discuss on the next slide and typically, they allow all outgoing traffic. Stateful firewalls are more advanced than standard IP filtering firewalls.

These devices are able to keep track of the state of the communication between an internal and external device. It's able to build a state table to remember which devices were communicating with outside devices and when an outside device attempts to contact the device on the internal network. The firewall is able to recall that that internal device did request such traffic, and then allow that traffic into the network.

When an unauthorized communication enters the network and there is no matching entry in the state table. The firewall is able to realize that no device on the internal network asked for that traffic, and it can block that traffic from entering. It's able to do packet filtering just like a standard firewall would and it's able to dynamically allow that incoming traffic based on the user's requests.

Proxy firewalls or advanced proxy servers are also known as application layer firewalls or gateways. These are the middle man between two computers that are communicating with each other. These devices will make a copy of each packet, and then evaluate it after it's transmitted to determine if it's within or a violation of the security policy.

When this device is in place, there's no direct connection between the computers on the inside of your network and external devices. These devices are also able to hide the source computers IP address by copying the packet and inserting its own address using NAT or network address translation or PAT port address translation.

When you are evaluating packet data, you will introduce slag and slow down your network although most users are not going to notice this delay. Caching is a technology which allows the device to save a copy of recently requested pages. In case an additional user asks for those pages, it does not have to reach out to that website to download a copy of the page, it can just use the page that has been stored in the cache to increase speed.

Proxies also log activity, which can be very helpful if you have an employee who's violating your security policy. Or if an incident occurs, your incident response team can use these logs to try to determine what type of malicious activity occurred on the network. Application layer proxy firewalls are able to do state full packet inspection and more.

They can look deep into packets and make decisions by revealing the data and even reassembling fragments of traffic back together to determine exactly what is happening with that transmission. It can give you more granular control over the traffic that's coming in or leaving your network and because it understands applications.

It's able to understand the content of what's being transmitted and help to block malicious content from entering your network. Anonymizing proxies are able to hide a sender's information in order to prevent the recipient from knowing where the traffic actually originated. HTTPS interceptors are able to decrypt HTTPS traffic, view the traffic to determine if it's malicious or if it violates the security policy.

And then they're able to re-encrypt the traffic and forward it on to its original destination. Web application firewalls are an important security mechanism for web servers to protect them from a variety of threats. Reverse proxy will allow load balancing, so that if there's a large amount of traffic it can be distributed among multiple devices in order to increase efficiency.

This concludes our firewalls module. Thank you for watching.

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