Hosts file editing

Introduction to DNS and the Hosts File#

When you type a website’s URL into your web browser, have you ever wondered how your computer knows where to find the website’s server? The answer lies in the Domain Name System (DNS), a global network of databases that maps hostnames to IP addresses. In this guide, we’ll explore the role of the hosts file in resolving hostnames to IP addresses and how to edit it using tools like Gas Mask on Mac or HostsMan on Windows.

How DNS Works#

When you enter a URL into your browser, your computer sends a request to a DNS resolver, which is usually provided by your internet service provider (ISP) or operating system. The DNS resolver breaks down the URL into its constituent parts, including the hostname (e.g., www.example.com). The resolver then queries a series of DNS servers, known as name servers, to determine the IP address associated with the hostname.

Here’s a simplified overview of the DNS resolution process:

1. Your computer sends a request to the DNS resolver.
2. The resolver breaks down the URL into its constituent parts.
3. The resolver queries a root name server to determine which top-level domain (TLD) server is responsible for the hostname.
4. The TLD server directs the resolver to a name server that is authoritative for the hostname.
5. The name server returns the IP address associated with the hostname to the resolver.
6. The resolver returns the IP address to your computer, which can then connect to the server.

The Role of the Hosts File#

The hosts file is a local database on your computer that maps hostnames to IP addresses. It’s a plain text file that contains a list of hostname-IP address pairs, one per line. The hosts file is used by your operating system to resolve hostnames to IP addresses before querying the DNS resolver.

The hosts file serves several purposes:

• Local development: Developers often use the hosts file to map a hostname to a local IP address, allowing them to test websites or applications on their own machine.
• Blocking unwanted websites: You can add entries to the hosts file to block access to unwanted websites or redirect them to a different IP address.
• Testing and debugging: The hosts file can be used to test changes to a website or application without affecting the live version.

Editing the Hosts File with Gas Mask (Mac) or HostsMan (Windows)#

While you can edit the hosts file manually using a text editor, it’s often easier and safer to use a dedicated tool like Gas Mask on Mac or HostsMan on Windows. These tools provide a user-friendly interface for managing the hosts file and can help prevent errors or conflicts.

Gas Mask (Mac)#

Gas Mask is a free, open-source application that allows you to easily manage your hosts file on Mac. Here’s how to use it:

1. Download and install Gas Mask from the GitHub repository: https://github.com/2ndalpha/gasmask
2. Launch Gas Mask and click on the “Hosts” tab.
3. Click the “+” button to add a new host entry.
4. Enter the hostname and IP address you want to map, and click “Save”.
5. To activate the new host entry, click the “Apply” button.

HostsMan (Windows)#

HostsMan is a free application that allows you to manage your hosts file on Windows. Here’s how to use it:

1. Download and install HostsMan from the official website: https://www.abelhadigital.com/hostsman/
2. Launch HostsMan and click on the “Hosts” tab.
3. Click the “Add” button to add a new host entry.
4. Enter the hostname and IP address you want to map, and click “OK”.
5. To activate the new host entry, click the “Apply” button.

Example Use Case: Local Development#

Let’s say you’re a web developer working on a new website, and you want to test it on your local machine. You can add an entry to the hosts file to map the website’s hostname to your local IP address (e.g., 127.0.0.1).

Using Gas Mask on Mac:

1. Launch Gas Mask and click on the “Hosts” tab.
2. Click the “+” button to add a new host entry.
3. Enter the hostname (e.g., example.com) and IP address (e.g., 127.0.0.1), and click “Save”.
4. To activate the new host entry, click the “Apply” button.

Using HostsMan on Windows:

1. Launch HostsMan and click on the “Hosts” tab.
2. Click the “Add” button to add a new host entry.
3. Enter the hostname (e.g., example.com) and IP address (e.g., 127.0.0.1), and