Category: Networking

How To: Add A New Line With CURL

Today’s article isn’t going to be all that long and it’s definitely not going to be complicated, as we just discuss how to add a new line with curl. It’s just an annoyance factor and something I was reminded of today. Lacking a better idea, I decided I’d use this annoyance and recollection as a reason to write an article about how to add a new line with curl.

First, this obviously requires a terminal.

Second, this obviously requires curl. You almost certainly have curl installed, so you won’t have to install anything. 

If you’re curious, you’ll find that the curl man page defines the application as:

curl – transfer a URL

You’ll understand why I’d use that in a second, but you can imagine that it’s a pretty handy tool to have in your Linux toolbox. We’ve previously used curl in many articles. Here’s a sampling of those articles:

Let’s Have a Limited Look at Linux’s cURL Application
Weather In The Terminal? We can do that!
How To: Find Your IP Address Through Your Terminal

… and more!

So, in this case, I show ads on the site. To do this, Google relies on a file known as ‘ads.txt’ being in your web’s root folder (often called ‘public_html’). If the file is not there, there’s an ad inventory issue and Google won’t show ads.

Well, if you read the previous article you’d know that there was an outage. During this outage, it appeared that the site was still reachable – except it wasn’t. It was during this time that AdSense decided to check and see if the ‘ads.txt’ file is there. (This is nothing private. Everyone using AdSense has an ads.txt file.)

Because of this, I decided to verify that the ads.txt file existed and contained the appropriate information. To do this, I simply used the following command:

It gave me the answer I wanted, but I disliked the formatting of the output. But, it was enough for me to determine that the file existed and that I just had to wait for Google to confirm this.

The formatting was horrible. I’ll show you an image in the next section and you’ll see…

Add A New Line With curl:

So, when I saw the output from the above command (feel free to run it on your computer), it just ran the line into the next prompt. I had to dig through my ~/bash_history file because I couldn’t remember how to fix the formatting.

A picture is probably going to describe this best. In the picture, you’ll see the ugly formatting and you’ll see the solution.

adding a new line to the curl output
As you can see, the second command has a much nicer output.

So, to make sure you have a new line, you use the -w (write-out) flag and add the character for a new line in quotes – which is "\n". It’d look like this:

As you can see (and I hit the enter button between commands to start on a fresh new line) the output is much nicer. So, instead of curl starting a new line, a command entry line as it were, you’re starting with a nice fresh new line.

I messed with this way too long before I started digging into my bash history to find other curl commands used over time. Eventually, I found it, but I’d already verified that the file existed and that Google would notice the next time they checked.

Closure:

Well, it’s not the greatest of articles – but it’s useful if you want to know how to add a new line with curl. It’s a much tidier output this way. I just need to remember to do it without having to dig through my bash history each time I want to have a clear curl output.

Meh… I’m sure it’ll eventually be handy for someone…

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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.

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How To: Change DNS Servers

Today’s article shouldn’t be all that difficult for even our newest users but is limited to those who want to change DNS servers to something other than the default. This is easy enough to do, but obscure enough to warrant an article of its own. 

First, let’s have some fun. I’m going to ask ChatGPT to tell you about DNS in just two paragraphs. So, let’s see what the AI has to say:

First, what is DNS?

DNS, or the Domain Name System, is a fundamental protocol used in computer networks to translate human-readable domain names into machine-readable IP addresses. It serves as a decentralized directory system that enables users to access websites, send emails, and perform various network activities using familiar domain names instead of numerical IP addresses. When a user enters a domain name in their web browser, the DNS resolver (typically provided by the Internet Service Provider or ISP) initiates a series of queries to locate the corresponding IP address. The resolver communicates with DNS servers, starting from the root servers, then the top-level domain servers, and finally the authoritative name servers associated with the requested domain. Through this hierarchical process, DNS ensures efficient and accurate resolution of domain names, facilitating seamless internet connectivity.

DNS operates through a distributed database system known as the DNS namespace. This namespace is organized hierarchically, with the root domain at the top, followed by top-level domains (TLDs) like .com, .org, or country-specific domains such as .us or .uk. Beneath the TLDs, there are second-level domains, and further subdivisions like subdomains. Each domain has authoritative name servers that store the IP addresses associated with the domain names they manage. DNS resolution occurs through recursive queries, where the resolver traverses the DNS hierarchy to find the authoritative name servers responsible for the domain. Once the IP address is obtained, the resolver caches it for future use, reducing the need for repetitive queries. DNS plays a crucial role in the functioning of the internet by providing a scalable and efficient method for translating domain names to IP addresses, enabling seamless communication and accessibility across the network.

Wow! That’s pretty accurate. I’d have just resorted to describing DNS as the telephone book of the internet. You look up the name you want to reach and DNS tells you the number. In this case, the number is the IP address.

All in all, I’d say ChatGPT did a pretty fine job.

Change DNS Servers:

There are a variety of reasons why someone would want to change DNS servers to something else. They may get updated more quickly, weed out junk domains, or even remove ads and things like that. Maybe you want to weed out inappropriate material because you have children. Perhaps you have some custom configurations needed to traverse your complex local network. There are all sorts of reasons why you might want to change DNS servers.

See, as alluded to above, it’s perfectly possible to run your own DNS server (see Pi-hole for one such example). You can also use DNS servers provided by various third parties. For example, CloudFlare and Google offer their own DNS servers that are free for you to use. There are other choices, but this isn’t an encyclopedia writ large, so I’m going to just include those two. You can use your favorite search engine to find more.

So, let’s say you don’t like using a DNS server provided by your ISP. Perhaps you do this because of privacy issues, though you can look into DNS over HTTPS if you’d like. Perhaps you just don’t find them updated quickly enough or you’ve found they contain errors. (They do sometimes have issues and have even been known to be exploited in the past.)

NOTE: We’ll be using ‘nano‘ for this exercise. We’ll also default to Google’s public DNS servers, but you can substitute with whatever you find available.

Well, the first step you’re going to take is opening your terminal. You can do that by just pressing CTRL + ALT + T. In most distros, that will open the default terminal emulator. If your distro doesn’t do so, start mucking about with the keybindings until it does!

The file we’ll be editing doesn’t actually exist on most distros. That’s not a problem, because we’ll be making that file with nano. With your terminal open, enter the following command:

That should be a perfectly blank file and you’ll want to enter the following (again, using Google’s public DNS servers) to change DNS servers:

Then, you’ll save the file with Nano. That’s pretty easy. To save this new resolv.conf file with nano, you just press CTRL + X, then Y, and then ENTER.

Next, you’ll need to reboot. I know this will pain some of you, but I’ve yet to have a sure way to effect these changes other than rebooting. So, you’ve gotta do that. Try this command:

Now that you’ve managed to change DNS servers, you should be able to browse around much as you normally would. Remember, the people in charge of the DNS servers are the ones that decide where you go when you enter an address into the address bar and smash that enter button.

Be sure to use a company you trust to provide those services and be sure to verify your internet is still working properly. If it’s not working, you can remove the file and reboot or you can edit it again and try rebooting again. It shouldn’t be a problem in reality, this isn’t anything all that complicated.

Closure:

So, there you have it. It’s yet another article. This time around we discussed how to change DNS servers – along with some reasons as to why you might want to. If you have a spare bit of hardware kicking about, you can make your own DNS server and point to that with the internal addresses you’d be using. It’s nothing too painful and I think even beginning Linux users can follow along easily enough.

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A Fun Way To Check If Your Network Devices Are Connected

Today is going to be a fun article, mostly good for lazy people, where we discuss a way to check if your network devices are connected. There are far easier ways to do this, assuming you’re local to the device. If you’re not local to the device, the fact that you’re connecting to it likely means that the network is at least somehow connected!

But, in the spirit of being lazy, let’s head into the world of sheer, unadulterated laziness. I mean, if you want to know if your wireless is connected there’s an icon. Of course, you can see if your ethernet is connected. To check that ethernet connection all you probably have to do is look at the back of the computer and maybe wiggle the cable a little bit.

This, of course, presumes that said network adapters are in working condition. If they’re broken, this tool might give you a bit of debugging information. But, still, this is a command that calls itself a “beat connector”. It’s mostly used to check to see if your network devices are connected – as in physically connected to your computer.

The tool we’ll be using will be ifplugstatus and it defines itself as this:

ifplugstatus – A link beat detection tool

At least as far as I use it and the man page indicates, it checks to see if your network devices are connected. Seeing as that’s what the title suggests, it means we’re probably off to a good start!

Check If Your Network Devices Are Connected:

First things first… You’ll almost certainly find that ifplugstatus is not installed by default. You’ll need to install ifplugstatus if you want to use it. To do that, you’ll need an open terminal – which you’ll need for the rest of the article. To open your terminal, press CTRL + ALT + T and your default terminal should open.

Now, I’ve only ever used this command with Lubuntu and similar. Because of this, I don’t know if it’s the same on other distros. (Feel free to leave a comment.) But, at least in Lubuntu, not only is ifplugstatus not installed by default, that’s not the name of the package you need to install. No, that’s a different name and to install ifplugstatus you will want to run the following command:

You’ll need to adjust that command to match the distro you’re using.

Anyhow, with ifplugstatus installed, you can check if your network devices are connected with just the following command:

But wait! There’s more! You can get a lot more information about your network devices by adding the -v (verbose) flag to the command. That flag automatically assumes the -a (all) flag, so it’s just:

There you have it… Instead of just looking in the status bar section to see if wireless is connected, or even looking around the back to see if the cable is connected, you can just check all that right there in the terminal – without having to move much more than your hands! You’re welcome!

Closure:

Heh… There you have it! You have another article. If you ever want to check for a beat, that is to check if your network devices are connected, you now know how to do so. You can even SSH into another device and check to see which of its network devices are connected (beyond the obvious one you’re connecting with). You don’t even have to leave your seat.

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How To: Find Local Network Devices

Today’s article will be a bit of a weird one, as I share with you one way to find local network devices using the Linux terminal. I suppose network device discovery is typically seen as a dark art, something a malicious hacker might do, but it’s completely harmless (in and of itself). So, if you want to find local network devices, this article just might be for you!

What we’ll actually be doing is scanning a block of IP addresses to see what responds to our prodding. This is sometimes called IP Scanning or IP Sweeping. It’s also sometimes called Port Scanning, but we won’t be doing any real port scanning. I assure you, I am not secretly trying to turn you into a big bad hacker – but this is a pretty neat ‘hack’ (in the traditional sense of the word).

We will be learning just a single command (with a bit of explanation) with a single flag. It’s a very complicated tool and trying to cover it all would take a giant article or many smaller articles. You can guess which one we’re going to do!

The tool we’re going to use for this is called ‘nmap’. This is available in every major distro. It might be installed by default. It’s just the tool for the task at hand, so you need to install it before you can use it as this article will suggest. (I trust you to know how to do so at this point.)

Did you install nmap? If so, please continue. If not, read the last paragraph.

With nmap installed, you can check the man page to see that it’s described as:

nmap – Network exploration tool and security / port scanner

Now you’re ready…

Find Local Network Devices:

Picture this…

So, for some reason, one of my laptops has stopped answering on the .local domain when I want to connect to it with SSH. I have choices at this point. I could fire up Team Viewer and then connect to the laptop to find the IP address belonging to the said laptop. Another choice would be to get off my lazy butt and walk to the device, but that defeats the point of remotely controlling the device.

I suppose the best choice would be to just figure out why it’s stopped responding on the .local domain. Wouldn’t that be novel?

But, I have another tool! I have a tool that’s reasonably fast, very easy, and likely effective! That tool is, as suggested earlier, nmap.

The first thing I do is crack open a terminal to find my local IP address. That’s easy enough and the link will show you how to find your private (or local) IP address. Though it needn’t be private. Security by obscurity is not security – and it’s trivial to learn. But, that’s an article for another day.

I was able to quickly learn that my local IP address is 192.168.215.88. From this, I realize that the most common configuration will be for everyone to be on the same subnet and so my laptop likely falls within the 192.168.215.1 to 192.168.215.255 range.

We can use the asterisk to represent any of those numbers, as it’s a wildcard. This means the next command is obvious and will be simply:

The -sn flag would mean ‘do not do a port scan’, so it’s checking only for devices that return a ping. Make sense? (It’s a pretty speedy command when not also scanning ports.)

A Picture Of nmap:

I think that this is one of those instances where my text isn’t quite clear enough. So, what I’m going to do is show you a picture. 

The nmap command I ran showed me a list of local network devices. As I already know the IP address of the device I’m using, I can exclude that from the list. The device I’m looking for (my laptop) is then a different IP address.

The process looks something like this (trimmed down to just have one device for simplicity’s sake):

using nmap to find local network devices
As I know my device’s IP address, I can exclude that from the list of possible IP addresses.

As you can see, I first tried to connect with the .local domain and found that it did not work. So, I ran the nmap command and used a wildcard to scan the entire IP address range (1 to 255).

Sure enough, the IP sweep with nmap found another device and showed the IP address. It showed the gateway, which I could also exclude. The process of elimination meant there was one IP address to try (it could have contained more devices). I tried to use SSH with that IP address and, sure enough, that’s my laptop!

See? I saved a trip across the room! I saved opening up a bulky application and waiting for it to do its thing before I could even try using it to connect to the laptop. In fact, I suppose I also saved the effort I could have spent just randomly guessing IP addresses and hoping I got the right one for my laptop eventually!

Closure:

I figure there’s a lesson in nmap in there somewhere. You never know when you’re going to need to find local network devices! Now, when you do need to do so you will know how.

I figured I’d try writing this one in a way that showed you how I benefit from knowing how to do this. I figured that it’d be interesting to show you how the command solves a real problem. There have been a few articles similar to this and they’re fun articles to write. They are articles that come from the real me, the me that is actively using and appreciating Linux (often in the terminal) in my day-to-day life.

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