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Introduction
What is localhost? Localhost is a common term heard by users from a tech background or users working with web development or web hosting. Itis a reserved top-level domain that refers to the hostname of the current server or system accessing the network.
In this blog, we will discuss what is localhost. We will see the working of localhost and go through different uses of localhost in the following blog.
What is Localhost?
In computer networking, localhost is a hostname that refers to the current computer you are working with; here, the computer works as a virtual server. It looks for the website on itself rather than over the network. We can change the code on localhost and run it using localhost to test it without the internet.
When we enter an IP address, the computer tries to connect to the respected domain on the internet. For example, when we enter 13.35.128.17, the computer connects to www.codingninjas.com. But when you enter 127.0.0.1, the computer connects to localhost. It is a loopback address reserved for many different uses.
When a port number is combined with the localhost hostname, we get the socket address used to identify the network service running on the machine. Some of the default port used by various known servers are as follow:
HTTP: Uses port 80 to transfer data over the internet.
HTTPS: Uses port 443 for encryption to protect important data.
FTP: Uses port 21 to transfer files over the internet.
DNS: Uses port 53 to translate domain names to IP addresses.
For example, "localhost:4000" runs the web application you are currently working on. If you use Ontotext GraphDB, the socket address is "localhost:7200".
Fact: The IP addresses with 127 as the first section are reserved for loopback addresses. So, when you enter an IP address with 127 as starting, the computer immediately recognizes and creates a loopback device.
To know more clearly about what is localhost, let's discuss the IP address and loopback address.
What is an IP Address?
IP is an abbreviation for "Internet Protocol." An IP address is a unique series of numbers used to identify any device over the internet. We usually enter some text for any website, which is a Domain name. The domain name is generally paired with an IP address.
The IP address contains four numbers, each of which ranges from 0 to 255—for example, 142.251.162.147. We always don't use these addresses as they are hard to remember, so domain names are used instead.
What are Loopback Addresses?
Some of the IP addresses are reserved for specific reasons. For instance, the addresses ranging from 127.0.0.0 to 127.255.255.255 are reserved for loopback addresses. But the most common of these addresses is 127.0.0.1.
External devices can't reach loopback addresses. When you send a request to a loopback address, it triggers a loopback, meaning the request is sent back to the server from which it came. As a result, loopbacks don't go through the internet, they stay in your local network.
Now let's discuss what is localhost used for.
Uses of Localhost
Now, we know we can use localhost to make requests to our own computer, but what is localhost used for? Let's discuss some of the common uses of localhost.
Website and Web Application Testing
Suppose you are a programmer developing a website. You definitely want to create a website that is best without any errors. So, you don't want to deploy an unfinished website on a web server; in this case, localhost is used.
Instead of deploying unfinished work, we can host our website files on our computer and make them accessible via localhost. Then, with the help of our web browser, we can access these files and simulate the experience of visiting the website from a device. Nothing is shared over the internet and kept on your computer.
Using localhost as a private testing server, programmers check the functionality of their websites. It is a common practice, as you can test your programs before deploying them finally over web servers.
Speed Testing
You always want to ensure that all your equipment works in excellent condition. A network administrator can use localhost to test the local network and its connection speed without requiring an internet connection. You can simply open the command prompt and type "ping 127.0.0.1" or "ping localhost" to perform the test.
This test will demonstrate how many data packets are sent, received, or lost and also how much time it takes to transmit data. This overall depicts how well everything is performing.
Blocking Unnecessary Websites
Lastly, administrators can reroute requests for known harmful websites to localhost to prevent attacks on the network. It is done by modifying a computer's host file, that file lists domain names and each one's associated IP address. Before the DNS, the host's file was responsible for converting domain names to IP addresses. Though mostly obsolete, host files can still be found on modern computers.
To avoid visiting a harmful site, you can enter the website's domain in the host's file and assign it to the 127.0.0.1 IP address. When the domain name is entered, the user will be sent back safely to localhost instead of the website. Many pre-made host files are available online, so admins don't need to start from scratch.
Blocking an unnecessary website can be done by editing the computer's host file, as discussed earlier. Following are the steps to perform it:
To open the host file, go to C:\Windows\System32\drivers\etc on your computer. A file named "hosts" will be present; open it with any editor.
In my case, I opened it with VS code; you can open it with Notepad++ also. Don't forget to run the VS code as an administrator. The following image shows the host file on VS code.
Now, add the website you want to block in the following format and save the host file. 127.0.0.1 website_URL For example, 127.0.0.1 www.google.com
After saving the file, it will show an error when you try to open the URL. Therefore you successfully blocked that website.
Localhost is a hostname that refers to a computer or machine currently making the request. To connect to the localhost, you can call the 127.0.0.1 IP address on your computer. When you call it, the computer communicates with itself.
How to do speed testing using localhost?
An administrator can use localhost to perform a speed test. To perform the connection test, you can simply call "ping localhost" or "ping 127.0.0.1" on a command prompt.
What is an example of localhost?
The localhost is the hostname referring local computer address, known as the loopback address. For example, "localhost:4000" is used to launch the web application you are currently working on.
Conclusion
We hope this article was insightful and you learned something new. In this blog, we discussed what is localhost. We also talked about IP address and loopback address in brief to have a better understanding of what is localhost. We also discussed some of the common uses of localhost in daily life.
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