How to block internet access for any application on Android with NetGuard

There are many options available in Google Play. But in this case, we recommend NetGuard. It is a free, secure, reliable, and ad-free application. It allows you to control the Internet traffic of any app with a simple tap.

First step

To use NetGuard, you must first download and install it on your Android device by following the link below:

Google Play | NetGuard – No-Root Firewall

Second step

Then open NetGuard on your Android and click “I agree” on the first prompt you see.

Third step

Activate the application by tapping the button in the upper left corner.

Fourth step

Next, tap “ok” as many times as necessary to allow “NetGuard” to create a VPN (Virtual Private Network) with which it can filter Internet traffic from applications.

Fifth step

You will also need to disable battery optimization for NetGuard (so it can run more consistently). You can do this by following the pop-up window that the application shows you or by going to Settings>Applications>NetGuard>Battery>No restrictions.

Sixth step

Finally, go back to NetGuard and disable Internet access for the applications you want by tapping the WiFi and Mobile Data icons. If the icon is green, Internet access is enabled, and if it is red, the application cannot use the Internet.

Remember that you can change the permissions in NetGuard at any time. You can also configure other advanced options from the application’s settings menu. For example, you can create whitelists or blacklists of applications, set rules by time or network, view the data usage of each application, and much more.

Is it safe to use NetGuard to block Internet access for an app or game on Android?

By blocking Internet access to applications through a VPN. You might think that this method can be dangerous for your privacy. But don’t worry, NetGuard VPN does not connect to any external server or collect your data. It only serves to block Internet access to the applications you choose. It is also important to note that NetGuard is an open-source application (you can view its code on GitHub). This is a guarantee that the application is transparent, and secure and does not hide anything strange in its operation. Thank you for reading. Bye bye!

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Differences between software firewalls and hardware firewalls.

A firewall is one more option that allows us to protect our systems. In fact, it is a barrier between our device and the network. It allows you to analyze connections and determine when there may be an unsafe connection that could put a computer, cell phone or any other device at risk. If there is any risk, it blocks it.

It is possible to configure different aspects. For example, create a whitelist and allow certain connections, block programs from accessing the Internet, ports, etc. We normally use a software firewall, which is basically a computer program that we install. There are free ones, such as the Windows firewall itself, but we have a wide range of options.

But we can also have a hardware firewall, which is another option we can consider protecting our systems and avoid network problems. Nevertheless, what are their differences?

Structure

The first clear difference is that a software firewall is a program, something intangible. On the other hand, a hardware firewall is a physical device. Although they have the same objective of controlling connections, there is a point of difference in their structure. An application is not the same as a computer.

Something similar occurs when using a physical VPN and another at the application level. Concerning software, we will be able to install it on the system, while a hardware firewall will be an independent device on our computer.

Ease of use

This is a significant aspect to highlight. Is it easier to use a hardware or software firewall? This is undoubtedly a key factor in choosing one or the other option in most cases. Here the difference is clear, and it will be much easier to use a software firewall.

Concerning software, we will only have to install it on the system. Some even require little or no configuration. In fact, they usually come preconfigured with the basics to protect connections. On the other hand, if you use a hardware firewall, it will require physical installation and further configuration. It is more oriented to more experienced users.

Security

Clearly, security is one of the reasons why we use a firewall. We want to maintain maximum protection and not have problems with malware or attacks that can compromise our systems. But which of the two options is more secure for our systems?

Let’s start from the fact that both are going to protect us. Of course, as long as we use the correct option. That is to say, not all firewalls will protect us equally, in the same way that not all antivirus programs protect us well, etc. However, a software firewall will receive updates more frequently and that gives it a plus. On the other hand, a hardware firewall will protect the connection that enters a computer, regardless of what operating system we are using at the time.

Usability

There are also differences in usability. A software firewall can be installed on your computer or cell phone. As a result, it is a program that will remain there. If we take that computer and move to another location and connect to another network, it will still continue to protect us.

On the other hand, a physical firewall is usually connected to the router. It will be less flexible to move it from one place to another. Therefore, at the home user level, the most useful thing is software and not a physical device.

Price

There are marked differences in this regard. A software firewall can be free, such as Microsoft’s own firewall or many other options found on the Internet. There are also very low-cost ones.

On the other hand, a hardware firewalls will be more expensive and is an investment that we will have to make. Therefore, if you are looking to protect your computer and do not want to make a financial outlay, the best option is undoubtedly a software firewall. You will avoid having to purchase a device, with what that may mean as for price.

Which one to choose

After having explained the main differences between a software firewall and a hardware firewall, let’s talk about when to use one or the other option. This way you will be able to choose which one suits you best according to the use you are going to make of it. In addition, you can determine how you want to protect your device.

Protect one or many devices

The first thing to think about is what you are going to protect. A single device, such as a computer or cell phone, is not the same as an entire network. Logically, the latter requires more attention, since you will be able to connect many devices of all types. This will be key to choose what suits you better and purchase a physical device or a program.

If you are only going to protect one computer, such as a computer, it is better to use a software firewall. On the other hand, if you want to protect an entire network, you should ideally use a hardware firewall. This way, you will protect everything you connect to your network.

Home or business user

But if there is a clear reason to choose one option or another is to see if you are going to use it at home or for a company. The normal thing is that for personal use, to protect a computer or cell phone, it is best to use a program firewall. You will not require more than that, and so you do not have to spend anything or very little.

If you want to protect a company, where there will be many devices of all types connected, in this case it can be interesting to use a physical firewall. This allows malicious connections to be blocked for the entire network, and thus prevent problems from affecting essential components of an organization.

Where you will use it

The place where you are going to need it will also be a key factor in choosing one option or another. If you use a computer in different networks, such as at home, at work, in a library, on a trip… Undoubtedly, the ideal thing is to have a software firewall, since you will be able to take it anywhere.

On the other hand, if you are going to use it only in your home, work or any fixed location, then you might be interested in a hardware firewall. In that case you will not be able to move it, but you would not need it either.

Thus, we have seen the main differences between a software and a hardware firewalls. As you can see, they are two different options but with the same objective. They aim to protect your connections and prevent threats from entering your network and devices. See you later.

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How to bypass the firewall

A firewall is a software and/or hardware system that is responsible for controlling all incoming and outgoing connections between the local network and the Internet. It is also responsible for logically separating different subnets that we have in different VLANs. Its main function is to prevent and protect our private network from possible intrusions. With this in mind, it blocks access from the outside to the inside. A firewall can also be configured to limit traffic from the internal network to the external network. Therefore, we might encounter some kind of blocking implemented by the network administrator.

In many occasions users want to access the Internet without any kind of limitation. Indeed, knowledge of how to access blocked websites in a school or university can be an asset among students. The same is true at work. It is possible to want to access a resource blocked by the firewall. Consequently, it may be necessary to attempt to bypass the organization’s firewall.

Here we are going to analyze how to bypass the school, university or work firewall. Accordingly, we will check methods to bypass the firewall. This depends on how that particular firewall works. Some work at the DNS level. That is to say, the firewall itself will be in charge of providing us with local DNS servers where the filtering is done, in addition, the possibility of using external DNS such as those of Google or Cloudflare is blocked. Another common method of blocking is to check the SNI field of HTTPS connections. As a result, we could allow or block access to certain web pages. Finally, they could do a deep traffic inspection (DPI) to block traffic that they have defined in the rules.

Use a proxy server

Proxies are services that will act as intermediaries and handle requests for us. For example, if you want to view a game website, it is quite likely that you will look it up by typing the URL in the address bar and the firewall will block it. A proxy server avoids this because you are not visiting the game website directly. What we do is go to the proxy page, and you tell it to go to that page instead of us. It then shows you all the requested content, while the firewall only sees the proxy URL.

There are several types of Proxy, those based on HTTP and HTTPS. It is the latter that you should use. Indeed, if you use HTTP, all traffic will be unencrypted and could easily be blocked by the firewall. When using an HTTPS proxy, all communications between the user’s computer and the proxy server will be fully encrypted. Consequently, it is ideal for maintaining privacy and keeping the firewall out of the way.

When using a web proxy, you must consider that the browser you use must be correctly configured. Therefore, you must go to the network section and configure the IP address and port of the proxy, as well as the protocol it is using. Once configured, we will be able to surf the Internet through the Proxy. However, the traffic used by other programs such as Skype or Slack will go through the main Internet connection. In reality, there is no complete forwarding of traffic as with VPN services, only web traffic will move through the Proxy.

Use a VPN to keep your traffic out of sight

A VPN is even more complete than a proxy and also makes it possible to bypass the firewall at work or school. In this case, it is as if our data travels hidden through a tunnel thanks to encryption. Consequently, it keeps us safe from prying eyes such as the school itself, the Internet provider and more. In this way of working, our computer sends this encrypted data to a VPN server, which decrypts our data. It then reads where we want to go and goes there. It then sends the traffic back encrypted and bypasses the firewall without any problems.

A significant detail of VPNs is that all network traffic will go from your PC to the VPN server. In fact, it will not only be the web traffic, but also the Internet traffic of any program or process we are using.

Google Translate

Another method is to use Google Translate. Here we have to use the translation page function to use it. Then, when Google Translate translates that page, it loads the page on the server, translates it and sends us the result. This little trick is widely used to bypass firewalls when a website is blocked. In effect, we will use Google’s services to take us to the final website. However, this method has its limitations. Besides, it is quite annoying to have to use the hyperlinks inside the Google translator.

The use of this trick is basic. Just go to the Google Translate page. Once there, please upload the URL of the blocked web page. Allow the algorithm to detect the language automatically. Then, you have to translate the website to a different language than the original one. That’s it! As a result, you will have access to the website but in a different language than the original one. However, it is a way to access. Beyond the language limitation, it is likely that your organization will also block this domain from Google because it has been known to do this kind of thing. As a result, it may not work.

Type the IP address of the website

When surfing the Internet we use domain names because they are easier to remember. The reality is that those names are in charge of translating them to the DNS servers and then sending us to that IP address. If we put that public IP in the address bar of the browser we can bypass the firewall. Of course, as long as the firewall does not have a blacklist of IP addresses that cannot be accessed or does traffic inspection. A web page that we can use to find out that IP is WhatIsMyIPAddress.

This form of connection will only work in cases where the firewall blocks traffic at the DNS level. However, if the blocking is through DNS and IP, it will not work because it will also detect that we are connecting to unauthorized websites. If you cannot use Proxy and VPN to attempt to bypass firewalls, this trick might work well for you to connect without limitations. However, you will have to know in advance all the IP addresses of the websites you want to access, so it will be quite cumbersome.

Uses DNS over HTTPS

The DOH protocol allows DNS requests and responses to be made through the HTTPS protocol in a fully encrypted manner. If your firewall is blocking access to the Internet through DNS, if you use DOH in the web browser, you will be able to bypass the firewall easily and simply. This is because blocking this protocol is really complicated. Indeed, you would have to block HTTPS accesses to all DNS servers that support this protocol, including Google, so as a general rule this is not blocked.

This DOH protocol is already found in major web browsers such as Chrome or Firefox. It is even present in Microsoft systems. Consequently, it would be advisable to check your DNS settings over HTTPS if you can because this way you could bypass the DNS blocking. Okay, so we have seen how to bypass a firewall. We hope you will use this guide to avoid limitations in your work or school. See you soon.

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How a firewall works

A firewall is a software or device that acts as a door that closes or opens at will. Its function is to block or allow connections from a device. An example is to create a list with the applications that we want to block so that they do not have access to the Internet or the IP addresses that we do not want them to connect to a network. It is based on the use of rules. Once created, if they are not complied with, then it does not allow Internet traffic, either outgoing or incoming. This makes it difficult for intruders to access the network or remotely access our devices.

Consequently, the main function of the firewall is to create a barrier to allow or disallow connections. This wall is used to monitor communications between computers, warn of connection attempts that may be suspicious, etc.

How to block folders with firewall

The most recent versions of Microsoft systems incorporate their firewall. Besides being free, it works very well and is highly configurable. One of the options allows you to block a specific folder from accessing the Internet. However, this option is not integrated by default into the Windows Firewall. So, we will have to use a third-party solution. We are talking about Fab firewall, a free program that integrates with Windows Firewall.

How to Download Fab firewall

First, you have to download Fab firewall from here. As mentioned above, it is a free program that is available for the latest versions of Windows. An important issue is that it is not necessary to install anything. In fact, it is a fully portable program. Just run the .exe file and that’s it. Once executed, a window is displayed showing the connections previously blocked by other firewalls, including Windows Firewall itself. If you have not blocked anything, then nothing appears.

Adding folders

Subsequently, you only have to add the folders you are interested in. This is very useful if you have several applications installed in a single folder. This way we can block internet access to all of them and at the same time save time. With this in mind, just click on File and then select Add Folder Contents.

Next, you only have to locate the folder. Once started, the files included in the folder will be added to the list of locks. This action also adds the folder to the Windows Defender block list. From that moment on, everything inside that folder will be locked, and you will not have access to the Internet.

Blocked programs inside the folder.

Any program or application inside the folder will lose internet access. This way we can limit the total access at once. In effect, the action extends to all items within the folder. Actually, what Fab firewall does is to create a new rule every time we click on add folders. In addition, these rules are extended to the Windows Firewall itself. In fact, you can verify them from the same Windows application.

Additional features of Fab Firewall

Certainly, the most striking option is to be able to block folders with the Firewall. However, there are other very fascinating functions to discover. Although it is a simple app, it has more interesting things to discover.

Block applications

Another interesting action is to be able to block applications from connecting to the network. Let’s suppose you have a program installed, and you don’t want it to connect to the internet. Then this option is for you. Just click on the + icon, then search for the program, and that’s it. It will immediately be added to the block list.

Create lists

It also allows you to create lists, import, or export them. It is useful if you want to add a series of programs or processes that you do not want to connect to the Internet. These lists can be activated or deactivated at any time, which facilitates the process. Additionally, it is possible to export these lists to any other firewall. Even if it is on another computer.

Internet blocking

A very useful option is to be able to block the entire Internet connection by simply clicking a button. Great, isn’t it? Well, this is possible with Firewall Fab. Regardless of whether the connection is wired or Wi-Fi, we can prevent any program or process from connecting to the Internet. Please click on Firewall, then click on Block Internet. The Internet connection will be automatically interrupted. Of course, the connection to the provider will still exist, only now the firewall blocks connection attempts. Just test it by trying to open a web page. To reverse it, just open the same option, but this time unchecks the corresponding checkbox.

Very well, in this way we have seen how to block folders with Windows firewall. In addition, we show you some suggestions to get the most out of the program. See you later!

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What is SimpleWall and how to use it to prevent Windows attacks.

This is a tool for configuring the Windows Filtering Platform (WFP). I would like to point out that it is not a graphical interface to the Windows Firewall. It also does not make any changes to it. It works on the Windows Filtering Platform (WFP). This is a set of APIs and system services that provide a platform for creating network filtering applications. Moreover, this platform is not a Firewall itself. However, thanks to SimpleWall we will be able to create access rules.

Let’s take a look at some of its features:

• It is free and open source.
• A simple graphical interface with no pop-up windows.
• Rule editor with which we can create our own rules.
• It has an internal block list to block Windows spying and telemetry.
• It has a log of lost packets.
• Support for Windows services and its store.
• Compatible with IPv6 and localization support.

First steps with simplewall to set up the firewall

The first thing you have to do is to download the executable file from here. Then, just install it like any other Windows program. You will immediately see a screen like the following one:

As you can see, there is a toolbar with the following buttons:

• File: To access the options settings and work with files.
• Edit: to purge unused apps, search and update list.
• View: to choose display options and font.
• Rules: to configure how the rules work. It is convenient to leave it as it comes by default.
• Block list: to configure how the block lists work. Therefore, it is convenient not to modify it.
• Help: to go to the author’s website to get information, check for updates and see what version we have installed.

Just below this bar, there are other buttons. Their functions will be explained in more detail later.

How to create a rule and activate filters.

Let’s see how to configure the tool. Just below the toolbar, there are some buttons that serve this purpose. First, there is the button to activate filters. Note that filters are disabled by default. So to start using them, you must press it.

Immediately, the rules will begin to be managed. Specifically, those related to the internet connection. By default, SimpleWall blocks network requests. Consequently, you only have to allow or block connections according to your needs.

After several requests, the programs will be classified into allowed, blocked and silent blocked.

It is also possible to create temporary filtering rules.

On the other hand, if you click on the button marked with the arrow, then you can create a custom rule. In this case for Apps, but it also works for other sections.

In the Rule tab it is possible to work with local and remote IPs together with their port if necessary.

In the Apps tab, we can assign this rule to apply to a specific program. If nothing is selected, then it applies to all applications. Finally, click on Save when you are done.

Now, to view the newly created rule, just click on the User Rules tab. From there you can delete it, edit it and check if it is active.

Okay, so we have seen how to prevent Windows attacks with SimpleWall. Okay, so we have seen how to prevent Windows attacks with SimpleWall. As you can see, it is an elementary way to manage the Windows firewall. You will also increase the protection levels of your system. Bye!

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Why is it important to use a Firewall?

Although Linux is a very secure system, it is not perfect and can be attacked by an external network. Especially critical applications that make use of data such as database managers or others. Therefore, it is advisable to install a Firewall and establish adequate policies to protect your computer.

In addition to security, there is something that many people overlook and that is that in a Firewall we can not only block incoming connections but also outgoing ones. In this way, we will be able to know which applications are making connections with the Internet and make our decisions.

In Linux, there are a variety of Firewalls that can be classified as domestic or professional like PFSense. I believe that the domestic ones can work in many cases and we will work on them in this post.

How to Open Ports in Linux – Debian, Ubuntu, and derivatives

In these distributions, UFW is present by default. In case it is not then you can install it without problems.

sudo apt install ufw

After that, you can start opening ports.

The easiest way is to follow this syntax

sudo ufw allow [port]

This way, if you want to open port 26 for all protocols, just run.

sudo ufw allow 26

You can also specify a specific protocol for that port like UDP or TCP.

sudo ufw allow 26/tcp

In this case, only port 26 will be opened for the TCP protocol.

If you have to open many consecutive ports, then you can specify a range

sudo ufw allow 4000:4007/tcp

This will open all ports from 4000 to 4007 for TCP. Remember that you can change tcp to udp and enable them for that protocol.

To apply the changes run

sudo ufw reset

So, this way, you can open the ports in Debian, Ubuntu, and derivatives.

How to Open Ports in Linux – RHEL, CentOS and Fedora

Unlike Debian, Ubuntu, and its derivatives, in the RHEL family, another similar application is used to manage the Firewall and it is firewalld.

In case it is not installed, you can do it as follows

sudo dnf install firewalld

And after that, initialize it and make it run with the system.

sudo systemctl enable firewalld
sudo systemctl start firewalld

This application works with zones with public being the default zone. If we assume that this is the current zone, we can open a port as follows:

sudo firewall-cmd --zone=public --add-port=[port]/[protocol]

If you would like to open port 2122 of the TCP protocol, then you should run

sudo firewall-cmd --zone=public --add-port=2122/tcp

Unlike UFW in this case we do have to specify the protocol.

Similarly, you can specify a range of ports but still specify the protocol.

sudo firewall-cmd --zone=public --permanent --add-port=3220-3225/udp

In this case, I have opened ports from 3220 to 3225 in the UDP protocol.

To apply the changes run

sudo firewall-cmd --reload

This way you can open ports in Linux

Conclusion

Opening ports in Linux is very easy and can help you with a network problem. Also having a Firewall always increases the security of the system.

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Prerequisites and installation.

I would be using Ubuntu as demo OS here, Most of the Linux OS comes with that features by default.

Check status of firewall.

$ ufw status

Enable firewall.

$ ufw enable

Reload firewall. SSH may stope when you enable firewall. If you are working in virtual environment, connection may lost.

Allow and deny rules.

Allow ssh port

$ sudo ufw allow 22

Rule applied, check status.

Like port number, we can allow to open for a particular IP address.

$ sudo ufw allow from 192.168.42.142 && sudo ufw status.

What if you wants to allow a particular port for specific IP Addr.

$ sudo sfw allow from 192.168.100.100 to any port 22

Status check.

Deny a particular port for a specific IP addr.

$ sudo ufw deny from 192.168.100.100 to any port 80

Now, delete created rule, there are two methods and first option with rule number.

 $ sudo ufw status numbered

Here, I want to delete rule number 5.

$ sudo ufw delete 5

Let’s use another way to delete any rule.

$ sudo ufw delete deny from 192.168.100.100 to any port 22

Lets reset all firewall rules to default.

$ sudo ufw reset

You can manage incoming and outgoing rules as well, have a look.

GUI Tool for UFW

Install GUI application for the firewall.

$ sudo apt-get install gufw

With basic understanding of security, a moderate user can manage items as well.

Conclusion

UFW can be used by that user, which is having not so deep knowledge of IPTables. but still wants to manage securities of their server and services. With very quick deployment ports or IP addresses, level restrictions can be managed to have a similar impact as it was supposed to be with IPTables.

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GlassWire installation requirements

GlassWire has a free and a paid version. In this opportunity, we will use the free version. The first thing you have to do is download it from this link. Below are the minimum requirements to run the tool.

• Microsoft Windows 7, 8, 10 operating system in 32-bit or 64-bit version.
• An Intel Celeron processor at 2 GHz or higher.
• 1 GB of RAM.

GlassWire main screen

As soon as you run the program, you will see the following screen.

In the box with the word GlassWire you will find the program options. In the center, on the other hand, are shortcuts to the program’s main functions:

• Graph: displays a graph of the applications and traffic. It does so in terms of time, ranging from 5 minutes to a month.
• Usage: provides information on where the applications have been connected and what the incoming and outgoing traffic has been.
• Things: where we can see which computers are connected to our network.
• Firewall: is the section of the firewall where we can select which applications can connect to the Internet or not.
• Notifications: this is the section that alerts you of program activities to review.

Indeed, when you click on Use you will see the information we mentioned. But it also shows to which country the program is connected.

On the other hand, in Things we can scan to determine the devices that are part of the network.

Configuration of GlassWire, the free firewall for Windows.

The firewall screen is as follows.

The first thing you need to notice is that the firewall is turned on. Next, there are 3 modes available:

• Click to block: this is the default. It also allows all applications to connect. Then, from the list, you can manually block the ones you do not want to connect.
• Ask to connect: a dialog box will pop up asking if you allow the program to access the Internet. This is usually the classic way in which firewalls are used.
• Block all: he would leave all the applications without connection, for an emergency measure.

Let’s take a look at a small sample. If you press any app, let’s say the browser, then you will see a window like this:

If you click on Block, then you will stop the app from accessing the internet. But if you use the option to ask to connect, then you will see a popup window like this:

Consequently, you must allow or deny the connection to the network. Certainly, this is the safest option. It allows you to have tighter control over the connections. However, it is more tedious since we have to operate it constantly. Anyway, we have seen how GlassWire, the free firewall for Windows, works. See you soon!

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Key factors.

• Open Ports.
• Insecure or non-updated software.
• Weak passwords policy.
• Attacks on administrator accounts.
• Lack of physical securities.

Open Ports.

Ports scanning is the first thing that any Attacker would do before attacking your servers. They could get an idea of which service can be compromised based upon open ports. There are multiple methods to scan and identify open ports Nmap is one of them.

# apt install nmap
# yum install nmap

Insecure or non-updated software

If you are not updating the server regularly, attackers can gain access via using exploits. Misconfigures services can be harmful too. Always make sure to keep Operating System updated. Multiple tools are available to test vulnerabilities. OpenVAS is one of the famous tool that can be installed on the server to scan vulnurabitiels.

Install OpenVAS

#apt install openvas
#yum install openvas

Start Service.

# openvas-start && openvas-setup

Login to get reports.

Weak passwords policy

Using a tool like hydra attackers can gain access if your system is set up with weak passwords and have unwanted ports open. Always use complicated passwords and keeping them changing from time to time can reduce the chances of attacks. Let’s take a look at how hydra can be used to target servers with weak passwords. create a list of usernames and passwords with all possible combinations (userlist.txt & passwd.txt are created in my scenario).

# apt install hydra

Run command.

# hydra -L /root/userlist.txt -p /root/passwd.txt -u 127.0.0.1 ssh

Attacks on administrator accounts

Remember, if an attacker can gain access to an administrator account. An attacker can gain access to other servers as well. Even after having to have good securities, the hackers were able to gain access. Always make sure not to share passwords with unauthorized persons.

Lack of physical securities

Proving multi-factor authentications, providing physical locks can save servers from unwanted access. Do not provide any direct physical access like monitors or keyboards. Block all USB or other serial ports that can be attached directly to servers. No media file sharing has to be with critical operational servers.

Conclusion.

Today, we have learned how an attacker can gain easy access to servers & how to avoid it. Scanning ports with Nmap, system’s health check with OpenVAS are part of security assessment. In the next article, we will understand other aspects of security.

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A Firewall is a system that allows protecting a computer or a network of the intrusions that come from the Internet. A firewall behaves as a barrier between the Internet or other public networks and our computer. In the firewall, the incoming and outgoing connections are determined by established rules.

For this reason, it is convenient to take some time to adjust the behavior of the Firewall in the system. Today I will teach you how to configure a firewall in Ubuntu 20.04 / Debian 10.

Configure the Firewall in Ubuntu 20.04 / Debian 10

1.-Upgrade the system

Upgrading the system is always a vital task to perform these types of installations and configurations because doing so provides us with the latest security patches. In short, you’ll have a more secure system. To do this, open a terminal and write:

:~$ sudo apt update && sudo apt upgrade

As a result of updating the system, you will be able to work with the firewall with the certainty of having more updated and more stable packages.

2. Working with UFW the Firewall on Ubuntu 20.04 / Debian 10

By default, Ubuntu has a Firewall installed, but not configured. In other words, it’s almost like not having it. So you have to get to work on it.

First of all, you must enable the service. Without it, the firewall will not run.

:~$ sudo systemctl enable ufw
:~$ sudo systemctl start ufw

Now, it’s a good idea to see ufw’s default rules for the system. In this case, run:

:~$ sudo ufw show raw

If you plan to use a server, then it’s a good idea to allow connections from ssh.

:~$ sudo ufw allow ssh

In effect, the above command, tells the Firewall to allow input and output connections to ssh.

In case you want to “open” a port to be used by another application, you must run:

:~$ sudo ufw allow 321/tcp

Don’t forget to replace 321 with the port you want. If the application uses TCP or UDP, you must change as the case may be.

You can open as many ports as you need. However, these three are basic to working with the computer:

:~$ sudo ufw allow 80/tcp 
:~$ sudo ufw allow 443/tcp
:~$ sudo ufw allow 21/tcp

80/TCP: Used for HTTP
443/TCP: Used for HTTPS
21/TCP: Used for FTP

You can even make a rule to allow or deny connections from any IP address.

:~$ sudo ufw allow from IP

With this, you authorize that the applications that come from that IP the firewall will accept them. If the IP address cannot be located, you will see an error like this:

If you are sorry to allow connections to that IP, you can revoke the rule:

:~$ sudo ufw deny IP

Remember to replace “IP” with the corresponding IP address.

However, imagine you’re starting to build a network and you don’t know who to trust, so you can deny connections from all computers.

:~$ sudo ufw deafult deny incoming

It is also possible to list all the options that the firewall has. Show them with the following command:

:~$ sudo ufw --help

As can be seen, manipulating ufw from the terminal is very simple.

3. GUFW. A graphical program to configure the firewall in Ubuntu 20.04 / Debian 10

As can be seen, manipulating ufw from the terminal is very simple, but if you don’t feel comfortable using CLI, then it is possible to use a GUI for it.

With GUFW, you can configure a firewall on Ubuntu easily. Also, you can apply the same options, but with a convenient graphical management interface. To install it:

:~$ sudo apt install gufw

When you run it, you’ll see a very simple interface like this:

If you click on “Rules” and then on the “+” button you can add the rules we have done before per terminal. Remember to first enable the GUFW.

You can also check the logs that are generated.

As you can be seen, configure a firewall in Ubuntu is simple and provides us with the extra security needed for an operating system. Of course, if we speak at the enterprise level, there are even more customizable and payment solutions to further protect the security of businesses.

Now it’s up to you, tell us about your experience with ufw?

Conclusion

Computer security is not something to be taken lightly, which is why knowing how to configure a firewall is always a good idea. Even in operating systems as safe as Linux or BSD.

Now, with this post, you have the basic tools to configure a Firewall in a fast and easy way and have a more secure system.

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