What is a firewall for? Firewall - what is it? Standard PC Defender
Good afternoon, dear readers, Denis Trishkin is with you.
More than ten years ago, Microsoft introduced Windows XP SP 2 to the public. In this operating system, curious users immediately noticed a new application to protect their computer from malware. I was one of the people.
Today I would like to tell you what Windows Firewall is, what its main functions are and all the information related to it. After all, this is probably interesting not only to me.
Many users want to know what a firewall is in Windows, also called a Firewall.
If your computer is not protected, personal information attackers can gain access. This happens through malicious program code(known as a virus) that can not only crash the system, but also completely destroy files. The service was created specifically to block such actions.
Please note that protection must always be used, regardless of the type of connection to " world wide web"(modem, cable, satellite).
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Each network has a specific port that allows this or that information to get into the computer or back to virtual space. The presence of such channels directly depends on the type of traffic received or sent.
If there is no request from the computer to send any data, the firewall blocks the port before it gets to workstation. Sometimes installing some software, including online games, can open access to some gateways, which will reduce the level of security.
How do I know if there is a firewall?( )
Built-in standard program there is protection in everyone Windows versions, starting with XP SP 2. To check availability, you need to go to the “Control Panel”, and then select Firewall or Security Center. In the new OS from Microsoft, the “Firewall” item is placed separately.
How to check functionality on different versions of Windows?( )
System protection can be enabled, like many other programs in this shell. You need to do the following:
To test the firewall on new Microsoft operating systems you need to:
Setting up the application( )
In addition to new programs, the list must include all standard applications and add-ons - installed with the OS.
Sometimes it becomes necessary to add existing collateral to the exceptions. To do this you need to select " Change settings», « Allow another program» and click on the appropriate one. If it’s not in the list, the “” button will help. Review».
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What to do if there is no built-in protection?( )
Some versions of operating systems do not have a built-in Firewall. To protect your work machine from malware, you must install it. For this purpose, software or hardware firewalls are used.
Hardware
These include many wireless points access and routers providing required level security for home networks. This type can also be used for work purposes. The only thing that changes is the scale of the equipment, which allows it to serve more users.
Software
This type of protection is perfect for personal computers. For the most part, it is developed by other manufacturers. These mainly include so-called antiviruses, which, in addition to file protection, also offer traffic security. There are often many other additional functions. The most famous of them can be safely called Kaspersky and NOD. This paid programs, which are considered more effective than others.
Unfortunately, they also consume a lot of computer resources, causing other software to run slower. But if you choose whether they are needed or not, you can safely say yes. Considering the simply incredible number of different viruses, add “ infection"Without these programs there are many ways.
Do I need to install additional programs?( )
Firewall itself cannot protect the system 100%. At the same time, the software performs key functions. Therefore, first of all, it is installed (or simply turned on), and then steps are taken additional measures. These may consist of a system update or antivirus installation.
Using a firewall within the same network( )
Increasingly, today, computer users connect not only to the Internet, but also to networks consisting of several devices. And it’s not clear whether you need to enable the firewall on one device or on all of them at once.
The specialists developing this software said that the program needs to be used not only on all machines on the network, but also to check that it covers every connection.
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The main thing is that the firewall should always work unless a third-party program is used. This will keep your computer safe. Moreover, in 95% of cases, assembly with standard parameters. If there is a program third party developer, most likely the regular firewall will automatically turn off. This is provided to avoid conflicts within the system.
Sooner or later, every person who actively uses a computer and the Internet wonders what windows firewall? Not everyone knows how much this is effective tool, which is able to protect your computer from most external problems.
Correctly configured windows firewall in combination with antivirus program, are able to protect your computer from the vast majority of viruses and malicious attacks. What is a firewall and how to work with it, read on...
Windows Firewall, also known as firewall, is a program that checks all data and connections from the Internet that request access to your computer. Depending on your firewall settings, it either allows or blocks data entering your computer.
To put it even more simply, a firewall is a wall between the Internet and your computer.
The Windows operating system has a built-in firewall, but not everyone has it enabled by default and is located in in working condition. If you have installed on your computer pirated version Windows, then with a high degree of probability I can say that you have it turned off.
To check the status of your firewall, open the “Control Panel” and find the corresponding icon
By clicking on it, the firewall management window will open. If you see a green shield next to the connection, it means your firewall is enabled.
To configure the firewall, click the “Advanced settings” button in the left column
In this window you can view the rules for incoming and outgoing connections. When you first launch a program that requires an Internet connection, it will prompt you to create a rule for the firewall (provided that the firewall is active).
Besides third party programs, connection rules also have built-in windows programs and applications.
To enable or disable a rule, double-click on it; to create a new rule, click right click mouse on the corresponding connection (outgoing/incoming) and select “Create rule”
If you are interested in how to disable the firewall, I will tell you. To do this, return to the main firewall window and select “Enable/Disable Firewall...”
Then I think it’s clear...
Now let's see how this whole thing works. On the test computer I installed a program for downloading torrents - Utorrent. When you first start it, a firewall window appears warning you that the program is trying to access the Internet.
For normal operation program, click “Allow access”. Is it really convenient? Now, without your knowledge, not a single program will be able to connect to the Internet, just as not a single “infection” from the Internet will be able to connect to you.
To add to firewall exceptions already installed program. You need to open “Allow a program or feature to run...”
And there click on “Change settings”, then click on “Allow another program” and select it from the list. If the program you need is not in the list, click the “Browse” button and specify relative path to the program launch file
As you can see, anyone, even the most timid beginner, can configure the Windows Firewall.
Few people have any idea why a Firewall or, as it is also called, a Firewall, is needed in the Windows operating system. Next, we will discuss in detail what it is and why it is needed. Here you can also find out about the need for this program if you have an antivirus. Will be considered and best options for the Windows operating system.
What is a firewall or firewall
The essence of this software is that it controls all traffic, which enters and exits the computer over a local network or over the Internet. Thus, Firewall prevents unwanted traffic that does not comply with program rules.
Why do you need a firewall, what are its functions?
By his actions, he protects the hardware from infection various viruses, as well as from hacker attacks. IN latest versions operating room Windows systems standard remedy protection - firewall, installed by default in the software package.
It also prevents the emergence of infected advertisements, as well as the occurrence of pop-up windows that interfere with the operation of the computer. The firewall also protects against unauthorized access from cyber fraudsters and stores information about the user’s computer, preventing it from being transferred to the server and from third parties.
How does a firewall work?
The security that a firewall provides has a certain operating principle; it is the same for all types of firewalls. All received data from other computers is firewalled compares with established policy security, in case of detection of vulnerabilities or the presence of infected files that can harm the computer, it displays a corresponding notification on the computer screen and does not let them through.
This program is configured using packet filtering, when certain parameters are set that allow you to skip certain types of files and prohibit others.
Do you need a firewall if you have an antivirus?
Many people, when faced with a firewall, do not understand the difference between it and an antivirus. If there is a second one, they disable the firewall, which can subsequently lead to dire consequences. It is necessary to understand the difference between these two types of programs.
First do not allow malicious files to get into the computer system, the second ones are needed in order to fight viruses, which nevertheless penetrated the system, as well as to combat their spread.
The best firewall for Windows
Many different firewalls have been developed for the Windows operating system. In order to choose a specific one, you need to familiarize yourself with all the options. This article will present the 6 best firewalls in our opinion.
Comodo Firewall
This is a program that is distributed free of charge. She provides good level of protection from external threats and viruses. It provides the ability to instantly notify a computer user about a possible attack on the hardware. She updates automatically through the Internet. There is an advanced hint system that will help even novice users cope. Great for use at home. You can download from https://ru.comodo.com/software/internet_security/firewall.php
Avast! Internet Security
This free program, which comprehensively protects the computer system from network threats in real time. It has powerful firewall
, distributed along with this company's antivirus. Helps to completely protect your computer from external threats in the form of hacker attacks, viruses, and various spam. Link: https://www.avast.ru/internet-security 
AVG Internet Security
This is a whole software package that creates multi-level protection computer from external threats. It is distributed free of charge, the license is issued for a period of one year. Scanner included Email and anti-spam. Using a special cloud technology This program allows you to seriously save computer resources. You can download it: https://www.avg.com/ru-ru/internet-security 
Outpost Firewall Pro
A program with portable protection that has proven itself to be good in terms of combating network threats. It spreads shareware, free version available for 30 days. Doesn't consume a lot of PC resources. 
ZoneAlarm Free Firewall
A simple utility that allows you to protect your computer well in real time. It has flexible settings and is also distributed free of charge. To protect the financial well-being of users, it is checked daily credit card. For data backup 5 gigabytes are provided cloud storage. You can download it from the link: https://www.zonealarm.com/software/firewall/ 
Kerio WinRoute Firewall
An enterprise software package designed to protect computers in large local networks or office buildings. into it built-in URL filters, IP router, VPN service. It supports VoIP and UPnP. 
It has high degree automation and a large number of settings. Distributed free of charge. It will be difficult for newbies to figure it out, but it's worth it. One of the most powerful and effective packages. Link:
What is a Firewall (Firewall)
Firewall or Firewall is a computer program whose purpose is to protect your computer from viruses and. The firewall is tracking network traffic, which enters the operating system and helps stop malware that tries to access the user's personal information. In addition, the terms Firewall and Firewall have another definition. These terms are commonly used to describe fire-resistant capital walls, which in theory should protect houses from fires in densely built areas.
What is a Firewall (Firewall) - in simple words.
In simple words, Firewall (Firewall) is special protective computer programs, which constantly scan data received and sent to the Internet. Figuratively speaking, these are virtual walls that protect your computer from the dangers of the Internet: viruses, rootkits, spyware, etc. Although it's worth noting that a firewall is not the only or most reliable source of protection for your computer. As a rule, to ensure the greatest security, a firewall (Firewall) always works in conjunction with antivirus and anti-spyware software.
In most cases, the firewall is installed directly on the work machine (PC), but sometimes, as in the cases of various offices where there are many computers, the firewall is installed as a physical device ( but more on that later). Windows operating system users do not need to install a firewall themselves ( separately), since the OS initially has its own - Windows Firewall.
Firewall - how it works, in simple words.
Without going into complex technical details, the work of the Firewall can be described as follows. When a user launches an Internet-related program such as a browser or computer game, the computer connects to a remote website and sends information about computer system user. However, before data is sent or received, it goes through firewall (firewall), where depending on set parameters, the data will be skipped or stopped.
Figuratively speaking, in the process of its work, the firewall acts as a kind of border guard or customs officer who monitors everything that is exported and imported onto the computer. In addition, his responsibilities include checking data packets for compliance with the required parameters. Thus, a firewall can help stop existing malware such as Trojan horses and other spyware from running. In simple words, the screen simply will not transmit the data collected by these programs to the Internet. But this, of course, is all in theory, since such malicious programs are constantly being improved and learn to deceive firewalls.
What is a Hardware Firewall and how to protect your network?
A hardware firewall is a physical device that connects a computer or network to the Internet using certain advanced techniques to protect against unauthorized access. Wired routers, broadband gateways and wireless routers include hardware firewalls that protect every computer on the network. Hardware firewalls are used to protect the network different types security: packet filtering, stateful packet inspection, broadcast network addresses and application level gateways.
Packet Filtering Firewall checks all data packets sent to and from the system. It forwards data based on a set of rules defined by the network administrator. This hardware firewall inspects the packet header and filters packets based on source address, destination address, and port. If a packet does not comply with the rules or meets the blocking criteria, it is not allowed to pass through the computer or network.
Dynamic packet filtering or stateful packet checking is more complex method protection. This firewall monitors where the packet came from to figure out what to do with it. It checks whether the data was sent in response to a request to receive additional information or it just appeared on its own. Packets that do not match the specified connection state are rejected.
Another way to ensure security is a network address translation (NAT) router. It hides a computer or network of computers from outside world, representing one publicly available for Internet access. The firewall IP address is the only valid address in this scenario, and it is the only IP address presented to all computers on the network. Each computer on the internal side of the network is assigned its own IP address, valid only within the network. This security option is very effective because it allows you to use only one public IP address to send and receive information packets. Which in turn significantly minimizes the possibility of introducing malware. This hardware firewall is usually implemented on a separate computer on the network, which has the sole function of running as a . It is quite complex and is considered one of the most secure types of hardware firewalls.
Basic problems with firewalls.
There are several common problems problems that may occur as a result of using a firewall. The most common problem is that, in addition to malware, the firewall often blocks the normal traffic we need. Some websites may have limited access or not opening up because they were misdiagnosed. Quite often problems arise with network games, since the firewall often recognizes such traffic as malicious and blocks programs from running. Based on this, it should be noted that although a firewall is a very useful thing, it needs to be configured correctly so that it does not spoil life with its prohibitions.
Categories: , // from |A firewall, or firewall, is a system that provides network security by filtering incoming and outgoing traffic, based on user installed rules. The main purpose of a firewall is to eliminate or reduce unwanted network communications. In most server infrastructures, firewalls provide a basic layer of security that, when combined with other security precautions, can prevent malicious attacks.
This article explains how firewalls work, specifically stateful software firewalls (such as IPTables and FirewallD), as they relate to cloud servers. The article covers TCP packets, different types of firewalls, and many other topics related to stateful firewalls. In addition, at the end of the manual you can find many useful links for manuals that will help you configure a firewall on your server.
TCP network packets
Before we start the discussion various types firewalls, become familiar with Transport Control Protocol (TCP) traffic.
TCP network traffic travels across the network in the form of container packets containing headers that contain control information (source and destination addresses, sequence of information packets) and data (called payload). The control information in each packet ensures that its data is delivered as expected and that its elements also support firewalls.
It is important to note that in order to successfully receive an incoming TCP packet, the recipient needs to send acknowledgment packets back to the sender. A combination of control information in incoming and outgoing packets can be used to determine the state of the connection.
Types of firewalls
There are three basic type firewalls:
- packet filters network layer(or stateless),
- stateful (or stateful),
- And application level.
Network layer packet filters work by analyzing individual packets. They are unaware of the connection state and can only allow or deny packets based on their individual headers.
Stateful firewalls can detect the connection state of a packet, making them more flexible. They collect packets until they determine the state of the connection before firewall rules are applied to the traffic.
Application layer firewalls analyze transmitted data, which allows network traffic to pass through firewall rules that are specific to individual services and applications. They are also known as proxy firewalls.
In addition to firewall software, available in all modern operating systems,Firewall functionality can also be provided by hardware devices (such as routers or hardware firewalls).
Firewall rules
As mentioned above, the network traffic that passes through the firewall is inspected using sets of rules to determine whether the traffic is allowed or not. The easiest way to explain firewall rules is with examples.
Let's say you have a server with a list of rules for incoming traffic:
- Accept new and previously installed traffic on network interface via port 80 and 443 (HTTP and HTTPS web traffic).
- Drop incoming traffic from IP addresses of non-technical office employees to port 22 (SSH).
- Accept new and existing incoming traffic from the office IP range to the private network interface via port 22 (SSH).
Notice the words "accept" and "drop" in these examples. With their help, you specify the action that the firewall should perform if the traffic matches the rule.
- Accept means to allow traffic;
- Reject – block traffic and return an “unreachable” error;
- Drop – block traffic and return nothing.
Network traffic passes through a list of firewall rules in a specific sequence, called a rule chain. Once the firewall detects a rule that matches traffic, it takes the appropriate action on that traffic. IN in this example According to the firewall rules, an office employee trying to establish an SSH connection to the server will be blocked according to rule 2 and will not be allowed to access rule 3. System Administrator it will pass the firewall because it meets rule 3.
Default firewall policy
Typically, firewall rule chains do not explicitly cover all possible conditions. Therefore, chains should always have a default policy, which consists of only actions (accept, reject or drop).
For example, the default policy of one of the previously mentioned chains is drop. If any computer outside the office tries to make an SSH connection to the server, the traffic will be dropped because it does not match any rules.
If the default policy is set to accept, then any user (except non-technical office employees) will be able to establish a connection to any open service of this server. Of course, this is an example of a very poorly configured firewall because it only protects services from non-technical people.
Incoming and outgoing traffic
Network traffic, from the server's point of view, can be either incoming or outgoing; firewall supports separate set rules for each type of traffic.
Traffic that originates from anywhere on the network is called incoming traffic. It is treated differently from outgoing traffic that is sent by the server. Typically, a server will allow outgoing traffic because it considers itself trustworthy. However, a set of outbound rules can be used to prevent unwanted communication in the event that the server is compromised by an attacker or a malicious executable.
To take full advantage of a firewall's security, you need to identify all the ways other systems can communicate with your server, create rules that explicitly allow that interaction, and then drop all remaining traffic. Keep in mind that you also need to create appropriate rules for outgoing traffic so that the server can send confirmations for allowed incoming connections. Additionally, keep in mind that the server typically needs to initiate its own outbound traffic (for example, to download updates or connect to a database), so it is important to think through these cases and create a set of rules for them.
Creating outbound rules
Let's assume the firewall drops outgoing traffic by default (drop policy). Therefore, accept rules for incoming traffic will be useless without additional rules for outgoing traffic.
To complement the previously mentioned inbound rules (1 and 3) and ensure proper interaction with these addresses and ports, you can use the following outbound firewall rules:
- Accept existing outgoing traffic on the common network interface via port 80 and 443 (HTTP and HTTPS);
- Accept existing outgoing traffic on the private network via port 22 (SSH).
Please note that you do not need to explicitly set a rule for dropped incoming traffic (rule 2), since the server will not establish or acknowledge this connection.
Programs and tools
So now you know how a firewall works, it's time to familiarize yourself with the basic packages that allow you to configure a firewall. Below you can read about the most common packages for configuring a firewall.
IPTables
IPTables is a standard firewall that comes by default with most Linux distributions.
Note: A more modern option is called nftables and will soon replace this package.
In fact, IPTables is a front-end for kernel-level netfilter hooks that can be used to control network stack Linux. It works by matching each packet crossing a network interface with a set of rules.
Instructions for setting up the IPTables firewall can be found in the following articles.