Firewalls

Firewall - the protective wall of your company

The function of a firewall is comparable to that of a protective wall in a house, which is why it bears this name.
The firewall consists of hardware and software and controls the flow of data between the internal and external network. This includes both the checking of data leaving the network and the checking of data trying to enter the network. Firewalls are generally used by companies.
This is due to the fact that it is essential for companies not to connect their computers to the Internet without protection.

The firewall makes it possible to control the computers and servers directly connected to the external network, while the individual workstations do not need to be secured separately. The firewall uses the IP address of the computer to check whether the data packet trying to enter the network is authorized to do so.
The firewall administrator creates lists of permitted senders (addresses) and only data from these senders may pass through the firewall.

Personal Firewall

In principle, the firewall and the slimmed-down version of the personal firewall for private use no longer have much in common. While firewalls for private use usually protect several computers at the same time, the PC tries to protect itself with the personal firewall.

The personal firewall runs on the PC itself and attempts to protect the computer from external attacks and prevent certain programs, such as spyware, from making contact with the Internet from the computer. It monitors all connections to other networks and analyzes both the requests to the Internet and the data coming to the computer.

The purpose of the personal firewall

is to ensure the security of the computer system against potential external attacks and to prevent specific applications, known as spyware, from communicating with the Internet. To this end, the personal firewall carefully checks all connections to other networks. This process includes analyzing requests to the Internet as well as evaluating data that reaches the device.

A personal firewall usually has the following functionalities:

Packet filter: This checks whether the data in the incoming and outgoing packets also comply with the rules defined by the user.
Sandboxing: This “locks” individual programs into a restricted environment.

Programs are executed in this implemented protected area. In the event of malware, it cannot cause any damage as the remaining systems remain unaffected by the isolation.

Configuration of the firewall

As with any program, the firewall configuration during installation is crucial.

Define the filter rules so that only the absolutely necessary accesses are permitted.
Check the settings regularly and block ports that are not required.
It is essential to always install and use the latest virus scanner.
Patches should be applied as soon as security vulnerabilities become known.
Security-relevant events should be logged and analyzed.

In order to understand the firewall's warning messages, it is advisable to know the meaning of IP addresses and host/computer names as well as the reported ports.

Some personal firewalls offer the option of a self-learning configuration. Every application that requires a certain connection for the first time is initially prevented from doing so and the personal firewall asks the user whether the connection should be allowed. In this way, a set of rules is gradually built up.
The advantage of this configuration is that it is easy to use, even for non-technical users.

When connections are made for the first time, the user is given the option of approving or rejecting them. A set of rules is gradually built up on this basis.
One advantage of this configuration is that it is easy to understand, even for technical laypersons, while a disadvantage is that it is susceptible to security-critical misconfigurations.

It is also essential to ensure the correct configuration of the web browser, the mail client, the operating system and the applications. In order to interpret the firewall's warning messages, it is essential to have knowledge of the meaning of IP addresses and host/computer names as well as the reported or warned TCP/UDP ports.

It should be noted that IT security cannot be achieved by a single piece of software, but always through the interaction of various factors. The term proxy server, which can be part of a firewall, is also mentioned in this context.
In this context, a proxy server acts as a kind of cache for frequently accessed websites, which enables faster access times by optimizing data transmission. However, if the data is not available, the corresponding page is loaded by the proxy server, stored in the cache and sent to the surfer. As a rule, the surfer cannot see where the data is coming from.

A proxy server is generally only used to speed up access to retrieved pages. In a firewall arrangement, however, it is responsible for checking the transmission integrity of the data. There is also the option of not transmitting certain data. For example, active content in web pages can already be blocked in the firewall.

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