Set Individual Flatpaks Permissions With Flatseal

This will be an article about Flatpaks permissions and how you can set said Flatpaks permissions with Flatseal. There’s a good chance that this will be a relatively short article, which is nice.

BEFORE YOU BEGIN:

I covered what a Flatpak is and some other bits of information. Read this:

Install Flatpaks In Lubuntu

That will give you an overview and enough information to get started. The only thing that will change is how you enable Flatpak and the Flathub repository. The method you use to do that will be different unless you’re using a distro that relies on the apt package manager.

What Is Flatpak:

I wrote this information out already, but some of you will not bother clicking immediately so I’ll mention that a Flatpak is an application that runs with its own dependencies and is sandboxed from the rest of the system.

The important part of this is that the developers who packaged the Flatpak set the permissions for that application. For example, their application may need access to the network. Their application may need access to storage media. The Flatpak may need to be able to access the sound manager so that you can hear things output by the application.

Well, you can adjust those permissions. If you want to grant additional access, you can do that. If you don’t need certain features, you can deny access to those resources. It’s up to you.

The developer shipped the Flatpak with a set of permissions. There are also default permissions that you can edit. If you want to do something like disallow all Flatpak access to the network,  you could do that. You can also adjust these permissions on a per-application basis.

Which leads us to this…

Set Flatpaks permissions with Flatseal:

If you want to manage Flatpaks permissions with Flatseal, you can start (and pretty much close this page) with the following link:

Flatseal on Flathub

The installation instructions will be available on that page. Alternatively, if you’ve already enabled Flatpaks (see the earlier link in this article) you can just press CTRL + ALT + T to open your terminal and enter the following command:

After you enter that into your terminal, you’ll press the Y button on your keyboard a couple of times to confirm that you wish to install.

With that said and done, you can then open your application menu, find Flatseal, and open the application. I’ll give you a screenshot, but there’s just so much more to this application that I can’t cover it. It’s fairly self-explanatory and you should be able to figure it out – but there are many options. 

Flatseal is used to adjust the permissions of a Flatpak.
That’s just the tip of the iceberg. Scroll down and there are maybe 50 options. Good luck!

There are just too many options for me to cover. The best way for you to learn how to use Flatseal is to simply install Flatseal and examine the options. If you have any questions about those options, reach out and I may be able to help. Otherwise, you can figure this out on your own.

I have faith in you. You can figure this one out!

Closure:

Well, you can now adjust Flatpaks permissions with Flatseal. I’m never quite sure how to pluralize or make it possessive, but I did my best. We’ll have to see how the final article does.

Anyhow, I told you this should be a fairly short article. It’s not designated as a short article because it’s a bit long for that and you have to read a bunch of other stuff if you want to use this as your starting point. If I could assume you had Flatpaks already enabled, this could have been a short article. I’ll make no such assumptions.

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Automate Updates In Linux Mint

Today’s article will be a fairly simple one and is limited to Linux Mint users as we learn how to automate updates in Linux Mint. That seems like a good idea to me. Ideally, this will continue working without any intervention, but we’ll see…

So, I’m not sure how long this has been an option. I only noticed it fairly recently. If you’re not already aware, you can automate updates in Linux Mint. It’s a pretty simple task and won’t require much more than a mouse – or maybe a terminal and then a mouse.

This can be a touchy subject. I’m firmly in the camp of immediately installing all updates. I want my system to be as secure as possible, which means applying the updates as soon as they are available. So far, this mostly appears to work.

Updates often come right before public disclosure and proof-of-concept samples. While it’s true that an update can bork your system, that’s easily fixed and such a rare thing that I don’t even consider it as a reasonable reason not to apply updates.

I also consider it my duty, my obligation, to keep my systems secure. An insecure system doesn’t just impact you. An unsecured computer can be used as a proxy, a command center, a spam relay, or a node in a DDoS attack, among other things. As a good netizen, I keep my systems updated.

So, why not automate that stuff when I can? 

Automate Updates In Linux Mint:

In your system tray, down on the right, look to see if you have an icon that looks like a shield. If you do not see the icon, press CTRL + ALT + T and type in mintupdate. Both of those things will open the Update Manager in Linux Mint.

At some point along this path, you’ll be asked to enter your password. Do so.

That will open this window:

to automate updates in Linux Mint, start with opening up the update manager
Your theme may mean this has different colors or whatnot, but it should look like this.

Next, you’ll click on ‘Edit’.

You need to click on the Edit button to move to the next step of automating updates in Linus Mint
This is a pretty easy step. Heck, they’re all easy steps! You’ve got this! I’m sure of it!

You next want to open Preferences and click on Automation.

You'll need to edit the preferences to automate Linux Mint Updates.
Just in case you’re confused, I added an arrow for you! (My CDN is going to hate me.)

When you’ve done all of this, you’ll face a new screen.

This new screen is where you edit your automation settings. This new screen is where you enable automatic updates in Linux Mint. It looks like this when I’ve configured it to my liking:

Enabling automatic updates in Linux Mint via the Update Manager preferences.
You can configure those however you like, but I enable all of them. You do you, I guess.

Make sure you have a viable backup process.

As you can see, I’ve chosen all the things. I’ve chosen to automate all the updating that I can do. If anything, I wish I could increase the frequency. I suppose I could set up a cron job for this, but a handy GUI is fine for this task. This way will also update Spices and Flatpaks. So, there’s that.

I’ve had this setting enabled for a little while now and I’ve verified that it has been working as expected. If you want to automate updates in Linux Mint, you can do that – and it’s not even difficult.

Closure:

I like automatic updates. I use that sort of feature online with my various websites. Scheduled updates performing themselves is a good thing to me. You may be more cautious, but I throw caution to the wind. I haven’t had an update nuke my system beyond a 2-minute repair job in forever. I haven’t even had a 2-minute repair job in years. That’s good enough for me. You can make your own choices. Regardless of your choices, be sure to backup your system regularly.

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Block A Specific Port In Linux Mint

If you’re using Linux Mint, you’ll find you have ufw already installed which means it’s easy to block a specific port in Linux Mint! I’ll explain how to do that in this article and do what I can to make it easy enough for a new Linux user to follow. If this interests you, read on!

You might want to block a port for all sorts of reasons. If you’re open to the public web via your router, you might find bots hammering at the default ports (such as 22 for SSH) trying to find the login credentials, even if none exist. This is unnecessary traffic and can cause the system to slow down if it’s overwhelmed with connection requests.

Also, Linux uses a lot of ports. There are a bunch that are reserved, for example. You can also designate your ports for many things. I’ve written articles about ports before, so here’s some light reading material:

How To: Check If A Specific Port Is Open
How To: Scan A Remote Host For Open Ports
Find Out What Process Is Listening On A Specific Port
Prevent Brute-Force SSH Attacks With fail2ban

About Ports:

Now, I think I’ll let an AI tell you what a port is in Linux.

A Linux port is a virtual concept that helps access different services within a network. A port is a 16-bit integer ranging from 0 to 65535 with no physical existence.

A port acts as a communication endpoint for identifying a given process or application on the Linux operating system. A port is a 16-bit (o to 65535) number that differentiates a single application from others on various end systems.

As the blurb says, these are virtual ports. They’re not like the physical ports on your router, or anything like that. They’re used for communication and sending traffic to a specific port is asking for traffic on that port. 

If you have nmap installed, you could run nmap localhost to find out which ports are open on your computer. You probably should run that command (you’ll need to install nmap with sudo apt install nmap before you can run this command in Linux Mint). If the port isn’t open, then you don’t need to block that specific port.

UFW:

Linux Mint comes with ‘ufw’ already installed. It is not enabled by default, however. It’s good that it comes installed, which means it’s almost ready for use and you only need to enable ufw for it to be of use. If you don’t know what ufw is, you can check the man page with man ufw to learn more. For simplicity’s sake, you’ll find that ufw is described as:

ufw – program for managing a netfilter firewall

We will be using ufw to block a specific port in Linux Mint. You’ll learn that ufw stands for “Uncomplicated Firewall” and is a frontend for iptables. You can do anything with iptables that you can with ufw, but ufw is much easier for a new Linux Mint user. It doesn’t need to be complicated, as you’ll see in this article.

Use UFW To Block A Specific Port In Linux Mint:

While there is a GUI front-end for ufw, we won’t be using that. Instead, we’ll just use the installed terminal and ufw. As you’re using Linux Mint, you can open your default terminal by pressing CTRL + ALT + T.

With your terminal now open, we first need to enable ufw because ufw is not enabled by default. To enable ufw, run the following command:

That will enable ufw on system startup. That command should output something that looks like this:

You can later disable ufw if you find you no longer wish to use it. That command would look like this:

Now, to block a specific port in Linux Mint with ufw, the syntax would be easy enough to figure out. It just looks like this:

If you want to block the default SSH port (port 22) then you can do that like so:

If you change your mind at a later date, the command to undo this would be:

All you need to do is remember ‘deny’ and ‘allow’ and that ufw commands require elevated permissions which means you need to use sudo. If you can remember that, you can block and unblock specific ports in Linux Mint!

Closure:

Yes, this article is about blocking a specific port in Linux Mint with the ufw command, but it applies to many other distros. I just happened to be using Linux Mint when I wrote the article and didn’t want to test on other systems before smashing the schedule button. So, I wrote it specifically for Linux Mint. This will likely be an accurate tutorial for Ubuntu, the official Ubuntu flavors, other Ubuntu derivatives, and maybe Debian. I’m not sure about Debian.

And now you know…

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Prevent Brute-Force SSH Attacks With fail2ban

Today’s article is one I could have already written and it’s about how to prevent brute-force SSH attacks with fail2ban. The reason I haven’t written it yet is because it either has too much substance or too little substance. I think I can strike a middle-of-the-road here and write an article with just enough substance.

See, and we’ll get to this later in the article, most folks won’t need to do a whole lot more than just install it. You can configure it a great deal, but the defaults are just fine for most people. On top of that, you can even make fail2ban send you email reports but we won’t be covering that in this article. Instead, we’ll largely have directions for installing fail2ban so that you can “prevent” brute-force attacks via SSH. I put the “prevent” in quotes because a diligent attacker could time things, use varied IP addresses, and try brute forcing your login credentials.

I think we need to start at the beginning.

What is SSH:

SSH stands for “Secure Shell” and is a tool to connect to a server remotely. If you check the man page for SSH it is defined as:

ssh — OpenSSH remote login client

This allows you to connect two computers over the terminal. It also comes with SFTP so that you can securely transfer files. You can do a whole lot more with SSH, including forwarding the graphical environment.

Here are a few SSH articles:

Install SSH to Remotely Control Your Linux Computers
Check Your SSH Server Configuration
Show Failed SSH Login Attempts

Then, there are a whole lot more SSH articles. I love SSH, so there have been quite a few articles on the subject. It’s a tool that I use quite often. I encourage familiarity with SSH as it’s sometimes a useful tool to effect a repair on a computer that is otherwise unresponsive to local inputs.

Servers are typically managed with SSH. As you can imagine, servers are a juicy target for malicious people. This means that SSH is a means with which malicious people will use to attack servers. One of the ways they do that is with ‘brute-force’.

What is Brute-Force:

There are many ways that one can try brute-forcing something. The name is as it implies. Rather than knowing the login credentials, they try to brute force them. That means they’ll try one combination of username and password and then keep trying various combinations until they eventually crack the system and figure out the login information.

That is the goal. Their goal is to find the login credentials. Instead of finesse, they use brute force.

This can include a dictionary attack. This can include a progressive attack where they start at the letter a, then try aa, then try aaa, etc. until they find the login credentials. They may also have a list of commonly used usernames and passwords and will systemically work their way through this until they find their way in.

This is one of many attacks and a modern computer can make many attempts in a short amount of time. Add to this modern bandwidth speeds and you can get thousands of attacks in just a short amount of time. It goes even faster if they know one part of the data, such as the username of a privileged account.

Enter fail2ban:

If you’re using a major distro, you have fail2ban available, one way or another. It’s usually easily installed and in your default repositories. When you do install it, you can check the man page. However, fail2ban is described as:

fail2ban – a set of server and client programs to limit brute force authentication attempts.

So, as you can see, fail2ban is the correct tool for the job. After all, and as the headline suggests, we’re trying to prevent brute-force SSH attacks with fail2ban.

Installing fail2ban:

We’ll be using a terminal to install fail2ban. You may also need to remotely connect to the server on which you want to install fail2ban. That too will require a terminal (or some SSH application like PuTTY). Simply press CTRL + ALT and your default terminal should open. If not, you can open a terminal from your application menu.

With your terminal now open, we can install fail2ban.

Debian/Ubuntu/etc:

RHEL/CentOS/etc:

Fedora with dnf:

I believe those are correct. That’s what is in my notes. If they’re not correct, please leave a comment and I’ll update the article. Other distros will have fail2ban available, just search your default repositories and you’ll likely find fail2ban available for installation.

Using fail2ban:

Now that you’ve installed fail2ban, you’re pretty much done. The default configuration is pretty much all you need – but you can customize it. There are a bunch of options available, so you can configure fail2ban in many ways. There are so many ways that we won’t be covering them. They’re reasonably obvious.

Once installed, fail2ban should start automatically. If it doesn’t, run this command to start it:

Next, we’ll make sure to enable fail2ban to start at boot time. That’s this command:

I assume that you’ll want to at least examine the configuration files and I’ll get you started with that. The first thing you want to do is cd to the right directory.

If you run ls you’ll see that there’s a file called jail.conf and you do not want to edit this file itself. Instead, fail2ban will look for configurations in a file called jail.local first. To make that file, you run the following command:

sudo cp jail.conf jail.local 

Next, you might want to make a backup of that jail.local file. 

You can now use Nano to edit your fail2ban configurations:

As you can now see, there are a bunch of options available. They’re far too many to explain here but they’re fairly well described. If any of the options confuse you, you can get help on the man page (man fail2ban ).

After you’ve set fail2ban’s configuration files the way you want them, you’ll need to restart the service for the changes to take effect. That’s done like this:

If you screw up the configuration, just remove the jail.local with this command:

Then restore from your backup like this:

Then, of course, restart the service with this command:

There are a lot of options with this application. You can explore them at your leisure, though I find the defaults to be adequate for most of my needs. As mentioned above, you can install sendmail and have the system send you notification emails. There are many other options as well.

Closure:

Like I said in the beginning, there’s a lot of substance with fail2ban. There’s a lot to it. If I added more to the article, it’d end up quite long. I may write a bit more about this application, but I don’t want to end up with a 2500-word article that will make your eyes gloss over. That doesn’t do me any good and it doesn’t do most people any good. Most folks are going to be fine with the basics before they explore the configuration options on their own.

If you do have a server (or even a personal computer) that’s running SSH, it’s worth your time to install fail2ban. If there’s any chance that someone can try to brute-force your system, they will.

Some bots crawl the ‘net looking for servers that respond on the default SSH ports. They can and will find you. You can also change the port SSH uses for some added obscurity (but remember that obscurity isn’t really security). So, it’s a good idea to prevent brute-force SSH attacks with fail2ban. Yes, it’s a good idea even for us ‘little guys’ who aren’t running servers with valuable information on them.  

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