Category: Tips

Geolocate A Website

Today’s article probably will be more about amusement than it is about education, as we learn to geolocate a website. This will not have a lot of uses for many of you, and the uses I can think of are a bit contrived. So, stand back and watch as we do some science!

Wait, no… No, there will be no science.

What I should have done is write this article ahead of time. Instead, it’s the 4th of July, and will probably be just about the 5th of July before I finish this. Let’s just all agree that I’ve been celebrating.

Anyhow, have you ever wanted to know where a website is located? Have you ever wanted to know where an IP address is located? Well, that’s what geolocation does and let me tell you that it is not excellent. No, it is not.

First, the tool we’ll be using is only going to give you the country. It doesn’t narrow it down very far.

Second, in the world of CDNs (Content Delivery Networks), a server may appear closer to you (or in this case the geolocation server) than it is. 

Relying on this data for anything important is just plain silly. 

But, you could log in to a remote server by name, get the local IP address, and then check the IP address to see what country the server is in. Yeah, see? I told you that any usefulness would be contrived.

Anyhow, you can geolocate by domain name or by IP address. With any luck, you’ll be able to tell which country the server is in. The previously mentioned caveats should make sure you know to not use these results for anything useful. 

Geolocate A Website:

You could almost certainly find an online tool that would do a much better job. Installing software for this is not necessary, but that’s exactly what we’re going to do. So, press CTRL + ALT + T and let’s get this party started.

First, we need to install a piece of software called Geoip. It’s available for all the major distros and describes itself as:

geoiplookup – look up country using IP Address or hostname

To install the software, you’ll enter one of the following commands into your terminal of choice:

RHEL, CentOS, Fedora, etc:

Arch, EndeavourOS, Manjaro, etc:

Debian, Ubuntu, Mint, etc:

When you’re done with that, it’s pretty easy to use. If you want to geolocate a website, the format follows:

And, if you want to geolocate an IP address, the syntax is similar:

An example output follows:

Which, you know, isn’t all that helpful. You can check the man page, but that’s also not all that helpful. To do that, it’s just this command:

The data isn’t entirely useless, for example, you can try this command:

Which, as you can see, appears to accurately geolocate the domain name to Canada, which is where I’d expect the server to be.

Closure:

So, yeah… If you want to geolocate a website then you can more or less do so. You’ll not get a whole lot of useful information and there are better tools for this online, but it can be done. You can indeed geolocate a domain name or an IP address all from the comfort of your terminal.

Just, you know, don’t use this information for anything too important. I use MaxMind for this sort of stuff online. It’s useful for getting meaningful statistics regarding the site’s traffic and is much more accurate, but still not accurate enough to pinpoint a house or anything. It can usually narrow things down to the nearest city, which is more than enough for my needs.

Thanks for reading! If you want to help, or if the site has helped you, you can donate, register to help, write an article, or buy inexpensive hosting to start your site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Show Files Installed With A Package (Using ‘dpkg’)

Today’s article is going to be quick and easy, as we simply cover how to show files installed with a package. Because I am reasonably compelled to optimize for search engines, the title just plain sucks. It should be much longer. Even though the exercise is really simple, explaining what we’re doing is a bit more complicated.

NOTE: The ‘dpkg’ may confuse some folks, but it means this article is only valid for those folks who are using .deb files, the apt package manager, and nothing else. So, if you’re using Debian, Ubuntu, Mint, or similar, then this article is meant for you. If you’re using a different distro, maybe I’ll cover those in another article.

So, what exactly are we doing?

Well, when you install software you don’t generally install just a single file. At least not if the software is all that complicated. 

Instead, you install all sorts of other files along with the software you’re installing. You don’t just install a single binary file, you install quite a few other files along with it.

Today, we’re going to list the files, the dependencies if you will, that go along with the applications we install. It’s not difficult, just a single command, but you can see why this would make for a very long article title.

Let’s keep this article short, as I’ve done some longer material lately:

Show Files Installed With A Package:

Yeah, you’re going to need a terminal for this. If you want to use ‘dpkg’ then you will need an open terminal. As that’s what we’re using, we need said terminal. In most distros you can just press CTRL + ALT + T and your default terminal should open.

The tool we’re using is ‘dpkg’ and the man page describes it like this:

dpkg – package manager for Debian

The ‘Debian’ bit is important. As I mentioned above, this only works for distros that use dpkg to begin with. Anyhow, that’s an accurate description of what dpkg does.

The command we’ll use is simply:

For example, you might try:

If you have Chrome installed,  you might try this command:

As you can see from the output, you’re generally installing a bunch of files when you install a new application. It may not appear that way during the installation process, but you’re most likely installing more than a single file each time you install an application.

Closure:

If you’ve ever wanted to show files installed with an application, now you know. It’s a pretty handy command to have if you’re into that sort of thing. If you’re playing the game of the lightest-possible-distro, then maybe you want to keep the number of files installed to a minimum and use the lightest software you can. Either way, it’s an informative command that should amuse my readers for five to ten minutes.

Thanks for reading! If you want to help, or if the site has helped you, you can donate, register to help, write an article, or buy inexpensive hosting to start your site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Disable Inactive SSH Sessions

Today’s article can be used by anyone that has started using SSH on their computers, as we learn to disable inactive SSH sessions. It’s not going to be a very complicated article. This is easy enough for anybody to do, and there aren’t too many ways to permanently mess things up.

What is SSH?

My regular readers will know that I’ve written quite a few articles about SSH. Basically, SSH stands for “Secure Shell” and is a tool you use to remotely control other devices through the terminal. The tool is ancient but still valuable. I use SSH regularly, and that’s not even counting the stuff I do online.

Indeed, I’ve written some SSH articles before:

Install SSH to Remotely Control Your Linux Computers
How To: Restart SSH
Show Failed SSH Login Attempts
(And many more.)

By default, your server/device may not close inactive or idle sessions. It will let you maintain your connection until you tell it to exit. This can be a security issue and it may be worth setting your SSH to disable inactive SSH services.

In this article, we’ll be using Nano and you’ll need to be able to use an SSH connection. If you don’t default to using Nano, you can install Nano or just use the default text editor that you’re more accustomed to. In theory, if you’re just practicing, you could set this up on your computer and then tell SSH to connect to ‘user@localhost’.

Disable Inactive SSH Sessions:

Up above I said, “SSH stands for “Secure Shell” and is a tool you use to remotely control other devices through the terminal.” If you were paying attention, you’d notice the last word is “terminal”. So, you’ll need an open terminal. For most distros, you can open a terminal easily, you press CTRL + ALT + T and you’re all good.

With your terminal now open, you’ll need to connect to the device that’s running the SSH server and enter the following command:

Next, you’ll add a couple of new lines. The syntax is straightforward and easy enough for anyone to understand. There’s a little bit of math, but you can do that math in your head. The syntax looks like this:

The first entry is how long you want to wait to check for an idle connection.

The second entry is how many times you want (set by the first entry) to check for an idle connection.

For example, look at this:

With the above, it’d check for an idle state every 300 seconds (five minutes). It will perform this check 5 times. If the connection is idle for all of those checks, the system will disconnect the SSH user. That’s allowing for 25 minutes of idle time before disconnecting the inactive user. That seems reasonable to me.

You can set those values to anything you’d like, perhaps shorter for an open office and longer if you’re using your home computer and connected to your own devices. The math doesn’t change. It’s just the number of seconds between text multiplied by the number of times the system will perform those checks. If you regularly have many users connected via SSH, you can save some resources by disconnecting them after a reasonable period of inactivity.

As we edited this with Nano, you’ll need to save the file. To do that, you simply press CTRL + X, then Y, and then ENTER and Nano will save the ‘ssh_config’ file.

After you have saved the file, you’ll need to restart SSH for the changes to take effect. That’s easy enough. Assuming you’re using Systemd, you restart SSH with this command:

If you’re still using SysV, the command would be this:

(I don’t bother with that often, I just assume you’re using Systemd. After all, according to the stats I can get, most of us are in fact using distros that use Systemd.)

Closure:

So, if you want to disable inactive SSH sessions, you can use the above as a template. You’ll need to figure out how long you want to wait between checks and you’ll want to decide how many times you’re going to make those checks. It’s simple math that anyone can do. It’s also probably not a bad step to take if you’re dealing with something public or sensitive.

Thanks for reading! If you want to help, or if the site has helped you, you can donate, register to help, write an article, or buy inexpensive hosting to start your own site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

How To: Kill Processes By Their PID (Process ID)

Today’s article is one my regulars will be expecting, as it is an article that teaches you how to kill processes by their PID (Process ID). This shouldn’t be a long or complicated article and I’d like to think a beginner can understand what it is that we’ll be doing.

If you aren’t familiar with a process PID, you should read the article that I wrote just so that I could write this article:

Find An Application’s Process ID (PID)

Seriously, if you’re at all unsure, read that article. You could even consider that article the first part of this article, except I didn’t want to make my article long. Besides, it’s quite likely I’ll be referring to PIDs in the future.

NOTE: The subject we’ll be approaching today can be quite complicated. In this case, there are all sorts of ways to kill processes. Because of this, we’ll just be covering a couple of very easy ways to kill processes by using their PID. 

Why would you want to do this? 

Well, like it or not, sometimes applications freeze and sometimes applications refuse to close. This is true on every operating system. It can (and probably will) happen. I just tried a pinball application last night and it refused to close. (I closed it using the GUI task manager, not via the PID. Shh!)

Why would you want to kill processes by their PID, especially when you can also ‘killall‘ processes by their name?

Sometimes, you have processes with names like this:

Instead of trying to close that with a command, it has a PID of its own and can be closed using that. It’s so much easier to use the PID for this that you might as well learn how to do it now. Again, it won’t be all that complicated. I’ll do what I can to explain just a couple of choices while we all safely ignore the many other options.

NOTE: This isn’t quite the article I intended to write, so there’s that. The people on the Linux.org forum will know what I mean. This is largely due to my horrible memory.

Kill Processes By Their PID:

Yeah, this is a terminal thing. As such, you’re going to need an open terminal. In most distros, you can just press CTRL + ALT + T and that should be enough to open up your default terminal emulator.

With your terminal now open, let’s have a look at the tool we’ll be using:

If you won’t want to look, the kill command describes itself like this:

kill – send a signal to a process

Handily enough, that’s what we’ll be doing. We’ll be sending a single to a process, specifically to kill the process. You can send other signals. You can send quite a few different signals. Enter this into your terminal:

But, we’re only going to concern ourselves with 9 and 15. Those are the only two we’re going to worry about today. The syntax of the kill command would look like this:

Of course, you’re going to need to know the PID. If you read the article linked in the beginning section, you’d know how to do that. But…

For the sake of this article, we’ll be using ‘shutter‘, as it’s a fine application.

So, if you didn’t read the article about finding an application’s PID, helpfully linked again, we can just use ‘pgrep’. If I run the command on my computer, I get:

So we can now see the PID for Shutter easily enough. (There are numerous ways to get an application’s PID. The pgrep application is generally pretty handy.)

The first command we’re going to try is asking the application to quit. We’re sending a command to the application and asking it nicely to die. That’s -15.

Using the PID gathered in the previous command, and knowing the proper syntax for this command, we end up with a command that looks like this:

Of course, sometimes the application doesn’t die when asked nicely. That’s not all that often, but it’s also not all that rare. It does happen and that’s when we skip trying to talk to the application and send a command straight to the kernel. That’d look like this:

That command tells the kernel to drop the application. In theory, this always works. You may still see the process listed in your list of processes but that’s just a zombie process and nothing to be too alarmed with.

You want to first try -15 because that closes the application more gracefully.  When you use -9 as your signal, you’re more or less just using a hammer to kill the process. If -9 doesn’t work, something is up with your kernel and it’s time to reboot. 

NOTE: The commands I used did not include ‘sudo‘. That’s because I owned the processes. If it’s a process owned by someone other than your user, you will need the correct permissions to kill it, such as sudo.

I am not going to cover them here, but you can send all sorts of signals with the kill command – not all of which kill the process. For more information, I highly recommend the following command (and then digging deeper into the rabbit hole):

I suspect you’ll find that to be more than enough information for one day, even though this article hopefully makes it so simple that a beginner can follow along. Hopefully…

Closure:

Well, there you have it. Here’s yet another article and this time we’ve learned how to kill processes by their PID. There’s so much more to this, but those are the basics. You can generally ignore the rest as an average user. You can also probably do a great deal of this with the task manager, all with a nice GUI. It’s worth knowing, and doubly so if you spend any time remotely connected to another device via SSH.

Thanks for reading! If you want to help, or if the site has helped you, you can donate, register to help, write an article, or buy inexpensive hosting to start your site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Change The ‘sudo’ Password Timeout

Today’s article is going to be a pretty basic article about sudo, where we learn how to change the sudo password timeout. It’s pretty easy to change the sudo password timeout value, and reasonably safe to do so if you use visudo. So, with that in mind, read on!

When you use sudo you’re given a grace period. During that time, you can use sudo again without being asked to type your password again. This is an arbitrary value, typically 15 minutes (I think), and you can customize that value for your particular environment. It’s not difficult.

This is something people may want to change if they’re slow, doing a lot with sudo, or have good physical security. This is also something that someone might want to change for the opposite reason. Some people may want to decrease the length of time that they have with sudo because they work in a shared environment. Who knows? It’s your computer, you can do what you want!

So, what is sudo? It’s how you temporarily use elevated permissions. In fact, I wrote a whole article on this subject, which you can read if you’re so inclined – and I’d suggest doing so if you’re new to Linux:

So, What Is ‘sudo’ Anyhow?

Well then, I mentioned another application. I mentioned ‘visudo’ above.

This may come as a surprise, but I actually wrote an article about visudo! You can read that as well, especially if you’re new to Linux:

Use visudo To Edit The sudoers File

Huh… It’s almost as if I’ve been waiting to write this article for a while and that I took the time to write articles that explain all these things. For a brief moment, one might be fooled into thinking I am good at preparing things. Little do you know… It’d be far more accurate to just say that I’ve written a bunch of articles already. I’d prefer it if you thought it was the former, but there’s definitely a touch of the latter.

Change The sudo Password Timeout:

If you clicked on either of the two links above, you’d know that those tools are used in the terminal. You didn’t click them, did you? Well, you’re going to need an open terminal. In most distros, you can just press CTRL + ALT + T and your default terminal should open. 

With your terminal now open, we’re going to use visudo to edit your sudoers file. In my particular case, we’ll be using Nano. (See? Yet another article you can rely on for more information about Nano!) The command to start banging away on your sudoers file would be simply this:

Now, I can’t say for sure that you’ll be using Nano for this. As you didn’t click the links above, I’ll remind you that visudo uses your default text editor. So, you’ll need to be prepared for that. Your default text editor may be Vim, for example, and you’ll need to know the basics to change your sudo password timeout.

NOTE: If you want, you can change your default text editor. (Did you see that? I did it again!)

Anyhow…

With your sudoers file now open for editing, you just enter the following on a new line:

As far as I can tell, most distros default to 15 minutes. So, you can use sudo and then you won’t be asked for the password again for the next fifteen minutes. In the above, you replace the obvious with the obvious. If you wanted 10 minutes leeway without retyping the password, you’d use this command:

If you wanted an hour’s worth of leeway without typing your sudo password again, then the command would just be this:

See? It’s not very complicated at all.

If you want to be fancy, you could include a comment. A comment starts with an # symbol and is thus ignored by the system. You might want to enter something like this:

By adding a comment, you’ll be reminded of what changes you’ve made from the default configuration. This is generally a good idea, especially if you’re going to heavily modify your system.

As this is Nano, you can finish editing the sudoers file by pressing the CTRL + X, then Y, and then the ENTER button. That will save the changes with Nano. If you’re not using Nano, you’ll need to refer to the manual (unless you already know how to save an edited file).

Closure:

And there you go! You can now change your sudo password timeout value to whatever it is you desire, assuming it’s whole minutes. I do not believe it works with fractions of minutes. You shouldn’t need to reboot or anything. It should take effect immediately and be the new timeout value the very next time you use a command that starts with sudo.

Of course, this comes with some security considerations. If this is a public kiosk, you’d have to be a fool to make this longer. You’d have to be a fool to have sudo access to begin with! That’s why they make guest accounts!

But, if you’re home alone and the neighbors aren’t going to sneak in to steal your wifi password, you’re probably good to go. Heck, if you are daring, you can use sudo without a password. I don’t recommend that, but you can… 

Also, this article contains a whole lot of links to other articles. Google will be pleased! I think it speaks to how many articles I’ve already written more than any foresight on my part.

Thanks for reading! If you want to help, or if the site has helped you, you can donate, register to help, write an article, or buy inexpensive hosting to start your site. If you scroll down, you can sign up for the newsletter, vote for the article, and comment.

Linux Tips
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.