One Minute to Understand What a Firewall Is

This passage introduces one of the basic knowledge points that CCNA network engineers must learn, that is, what a firewall is.

Generally, firewall is a network device that is based on a defined network policy and provides access control and security access scheme for the network. In addition, firewalls are often used as network address translation devices because they are often located at the boundary of the network and are the boundary to enter the network.

So, what characteristics should a good firewall have?

1. It has the function of logging and sending log reports.

Good logging and reporting capabilities are the basic capabilities of a firewall. Good logging capabilities not only enable network administrators to detect whether someone is constructing an attack against their network, but also enable them to detect whether normal communications sent from trusted users are used for other purposes. It is convenient for network analysis based on logs. However, a good logging function does not mean that all event information is recorded. The log report sending function, or passing capability, means that the firewall can not only record messages, but also timely notify the administrator of detected alerts. For example, it can inform the administrator by page, email or other means, and report the threat level.

2. It has the packets checking and filtering functions.

Another function of firewall is to check, audit and even filter data packets according to configured rules without seriously affecting network communication. Firewall is usually placed at the periphery of the network, and it is the only entry point to enter the network. Therefore, slowing down at this key entry point will slow down the entire network. Various factors affect the speed of firewall processing data.

3. It is easy to configure.

A firewall is easy to configure. It can be said that this is very important for all devices, and firewalls are no exception. It is very important to be able to quickly set rules, find problems, and operate the devices easily. A firewall that is easy to configure should be able to eliminate many errors when it is installed. It is very important to have a configuration program for the firewall. The configuration program makes it easy to convert the security policy of the site to the firewall configuration. Using a graphical network architecture as part of the configurator can avoid common configuration errors.

4. It is safe and has a redundant firewall.

If the firewall itself causes problems or is not safe enough, the impact on the network is great. The insecure firewall makes it easy for attackers to break through and further invade the network. In order to avoid the occurrence of events against the firewall’s own security, the firewall needs to be strengthened in the following two aspects:

Ensuring the security of operating systems: it is very necessary for firewalls running on a separate system to install patches or remediate vulnerabilities in a timely manner.

Managing access to the firewall for security: It is necessary to prevent security problems caused by access vulnerabilities by conducting corresponding administrative access to the firewall and setting reasonable authentication access policies.

A problem related to device security is the ability to deploy another redundant firewall in the network. This redundancy allows the backup equipment to perform the operation of the main equipment when the main equipment fails. Redundancy also allows the network to continue to operate when an attack makes the primary device inoperable.

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