Hosts文件，又名etc/hosts自 1984 年以来一直存在。每个操作系统都有(operating system)一个，包括Windows。您可能遇到过 etc/hosts 这个术语，但不知道它的含义以及使用它的原因。如果您是 Web 开发人员，您肯定知道这个文件是什么，并且想快速找到它。在本指南中，我们解释了Hosts文件是什么，它在Windows中的位置，(Windows)主机条目(host entry)是什么，以及如何编辑Hosts文件而不会遇到权限错误。让我们开始吧：
Windows 中的 Hosts 文件是什么？
Hosts文件（也称为etc/hosts）是Windows（和其他操作系统）用来将 IP 地址映射到主机名或域名的文本文件。(text file)该文件充当本地计算机的本地DNS 服务(DNS service)，它覆盖来自您的计算机通过网络连接到的DNS 服务器的映射。(DNS server)
Windows中的 Hosts 文件在哪里？
Hosts文件（或etc/hosts）位于以下文件夹中：“ "C:\Windows\System32\drivers\etc"
它是一个没有文件扩展名(file extension)的文件，可以在任何文本编辑器(text editor)（包括记事本(Notepad)）中打开和查看。
什么是 Windows 中的主机条目？
Hosts文件存储主机条目(host entries)。它们是使用以下格式的标准化文本行：IPaddress Hostname Comment。第一部分是要重定向到的IP 地址(IP address)，第二部分是要重定向的域，第三部分是注释。注释不是强制性的，只有前两部分是强制性的。您可以使用空格或TAB分隔(TABs)主机条目(host entry)的三个组成部分（按TAB键一次或两次）。例如，您可以添加一行：“127.0.0.1 www.google.com”
保存上述条目后，Windows会将域 www.google.com(domain www.google.com)重定向到您的所有应用程序和网络浏览器(apps and web browsers)中的本地计算机。
什么是 127.0.0.1？
127.0.0.1 是一个特殊用途的IP 地址(IP address)，它通向 localhost，也就是您的计算机。它也被称为“环回地址(loopback address)”，意思是使用该地址返回计算机的地址。与标准IP 地址(IP address)不同，环回地址(loopback address)不与任何硬件相关联，也没有物理连接到网络。安装在您计算机上的应用程序和服务(apps and services)使用此地址与本地主机（即您的计算机）进行通信。
您的计算机还有一个不同于 127.0.0.1的唯一IP 地址，与您的(IP address)网卡(network card)相关联，用于通过网络或 Internet 与其他设备和服务进行通信。
大多数情况下，在您的计算机上安装Web 服务器时会使用 localhost (web server)IP 地址进行(IP address)Web 开发(web development)，以便创建的网页可以在本地运行，并在Web 浏览器(web browser)中进行测试，就像它们在 Internet 上一样.
为避免计算机网络中的冲突，用于网络设备的IP 地址(IP address)可以是 127.0.0.1 以外的任何地址。例如，如果您手动尝试修改网卡的(network card)IP 地址(IP address)，在Windows中，您会收到一条错误消息：“以 127 开头的 IP 地址无效，因为它们是为环回地址保留的。请指定其他有效值在 1 到 223 之间。”("IP addresses starting with 127 are not valid because they are reserved for loopback address. Please specify some other valid value between 1 and 223.")
如何在Windows中打开和查看(Windows)Hosts (etc/hosts) 文件
您可以使用任何文本编辑器编辑(text editor)Hosts文件。例如，让我们(Let)使用记事本(Notepad)。首先(First)，也是最重要的是，您以管理员权限打开记事本(Notepad)（或您最喜欢的文本编辑器）。(text editor)一种方法是在Windows 10中搜索“记事本”("notepad")一词，右键单击（或点击并按住(tap and hold)）记事本(Notepad)搜索结果(search result)，然后单击或点击“以管理员身份运行”。("Run as administrator.")在显示的UAC 提示(UAC prompt)中，按Yes。
现在您需要打开Hosts文件。单击或点按文件(File)，然后单击打开(Open)，或按键盘上的CTRL+O
浏览至"C:\Windows\System32\drivers\etc"或将路径复制并粘贴到“(copy and paste)打开(Open)”窗口的地址字段中，然后按Enter。
起初，“没有项目匹配您的搜索”("no items match your search")意味着您看不到任何文件。这是因为 Hosts 文件没有文件扩展名(file extension)，而记事本(Notepad)只查找扩展名为“.txt”的文件。单击或点击“(Click)文件名(File name)”字段右侧的下拉列表，然后选择"All Files (*.*)."
现在您可以看到文件夹中的所有文件，包括hosts。选择文件并按Open。
如何在Windows中编辑(Windows)Hosts (etc/hosts) 文件
打开Hosts文件后，您可以编辑它，并添加、更改或删除条目，就像在任何其他文本文件(text file)中一样。
请记住(Remember)，您添加的所有条目都必须使用以下格式：IP 地址主机名(IP address Hostname)。添加一行“127.0.0.1 www.google.com”或“192.168.1.1 www.webapp.com”
编辑完Hosts文件后，您需要保存更改。如果进行了更改但未保存，请注意记事本(Notepad)窗口的磁贴以 * 符号开头。要保存更改，请转到文件(File)，然后保存(Save)或按键盘上的CTRL+S
保存更改后，它们会立即应用并覆盖来自您的计算机所连接的DNS 服务器的映射。(DNS server)
为什么人们使用 Hosts 文件？
大多数普通计算机用户不会使用Hosts文件，除非他们想对某人进行恶作剧并使用它来阻止他们访问Google、Facebook或其他网站，并让他们认为它已关闭，不再工作. 最常使用Hosts文件的人是创建网站和(Hosts)Web 应用程序(web apps)的 Web 开发人员，在将它们发布到 Internet 之前，必须在本地进行测试。
IT 专业人员还使用Hosts文件来阻止对他们在工作中管理的计算机上的特定站点和 Web 资源的访问。例如，他们可以使用它来阻止来自特定广告网络的业务网络中的广告。(business network)
恶意软件还可以使用Hosts文件将您的网络流量(web traffic)重定向到远程控制的服务器并窃取个人信息或其他数据。
我无法在Windows中编辑 Hosts 文件！我该怎么办？
在Windows(Windows)中编辑和保存Hosts文件时，您可能会收到一条错误消息(error message)，指出：“您无权保存到此位置。” ("You don't have permissions to save to this location.")发生这种情况是因为您没有以管理员权限打开记事本(Notepad)或正在使用的文本编辑器。(text editor)阅读以上部分，了解如何使用管理员权限启动记事本。(Notepad)
完成此操作后，您可以编辑Hosts文件而不会出现任何错误和权限问题。
如何在Windows中使用 Hosts 文件？
感谢(Thank)您阅读本教程。我们希望我们已经设法回答了您关于Hosts文件的所有问题。在结束之前，请在评论中告诉我们，您打算如何在Windows中使用(Windows)Hosts文件？是为了工作还是只是对朋友或家人(friend or family member)恶作剧？在下方发表评论(Comment)，让我们分享我们使用Hosts文件的经验。
What is the Hosts file in Windows? How to edit etc/hosts?
Τhe Hosts file, a.k.a etc/hosts has been around since 1984. Every operating system has one, including Windows. You may have encountered the term etc/hosts without knowing what it means, and why it is used. If you are a web developer, you surely know what this file is, and you want to find it quickly. In this guide, we explain what the Hosts file is, where it is located in Windows, what a host entry is, and how to edit the Hosts file without stumbling into permission errors. Let's get started:
What is the Hosts file in Windows?
The Hosts file (also referred to as etc/hosts) is a text file used by Windows (and other operating systems) to map IP addresses to host names or domain names. This file acts as a local DNS service, for your local computer, and it overrides the mappings from the DNS server that your computer is connected to, through the network.
Where is the Hosts file located in Windows?
The Hosts files (or etc/hosts) is found in the following folder: "C:\Windows\System32\drivers\etc"
It is a file with no file extension, that can be opened and viewed in any text editor, including Notepad.
What is host entry in Windows?
The Hosts file stores host entries. They are standardized lines of text that use the following format: IPaddress Hostname Comment. The first part is the IP address to redirect to, the second part is the domain that you want to redirect, and the third is a comment. The comment is not mandatory only the first two parts are. You can separate the three components of a host entry with spaces or TABs (press the TAB key once or twice). For example, you can add a line that says: "127.0.0.1 www.google.com"
Once you save the entry above, Windows redirects the domain www.google.com to your local computer, in all your apps and web browsers.
What is 127.0.0.1?
127.0.0.1 is a special purpose IP address that leads to the localhost, which is your computer. It is also called "loopback address," meaning an address that leads back to the computer using the address. Unlike standard IP addresses, the loopback address is not associated with any hardware, and it is not physically connected to a network. This address is used by apps and services that are installed on your computer, to communicate with the localhost, meaning your computer.
Your computer also has a unique IP address, different from 127.0.0.1, associated with your network card, that is used to communicate with other devices and services over the network or the internet.
Most often, the localhost IP address is used when installing a web server on your computer, for web development, so that the web pages that are created can be run locally, and tested in a web browser, as if they were live on the internet.
To avoid conflicts in computer networks, the IP addresses used for network devices can be anything except 127.0.0.1. For example, if you manually try to modify the IP address of your network card, in Windows, you receive an error stating that: "IP addresses starting with 127 are not valid because they are reserved for loopback address. Please specify some other valid value between 1 and 223."
How to open and view the Hosts (etc/hosts) file in Windows
You can edit the Hosts file using any text editor. Let's use Notepad, for example. First, and most important, is that you open Notepad (or your favorite text editor) with administrator permissions. One way to do that is to search for the word "notepad" in Windows 10, right-click (or tap and hold) the Notepad search result, and then click or tap "Run as administrator." In the UAC prompt that is shown, press Yes.
Now you need to open the Hosts file. Click or tap File and then Open, or press CTRL+O on your keyboard.
Browse to "C:\Windows\System32\drivers\etc" or copy and paste the path in the address field of the Open window, and press Enter.
At first, "no items match your search" meaning that you do not see any files. That's because the Hosts file does not have a file extension, and Notepad is looking only for files with the ".txt" extension. Click or tap the drop-down list to the right of the File name field, and choose "All Files (*.*)."
Now you see all the files in the folder, including hosts. Select the file and press Open.
How to edit the Hosts (etc/hosts) file in Windows
After you have opened the Hosts file, you can edit it, and add, change or remove entries, as you do in any other text file.
Remember that all the entries that you add must use this format: IP address Hostname. Add a line like "127.0.0.1 www.google.com" or "192.168.1.1 www.webapp.com"
When you are done editing the Hosts file, you need to save your changes. If changes are made and not saved, notice that the tile of the Notepad window starts with a * sign. To save your changes, go to File and then Save or press CTRL+S on your keyboard.
After you have saved your changes, they are applied immediately and override the mappings from the DNS server that your computer is connected to.
Why do people use the Hosts file?
Most casual computer users are not going to use the Hosts file unless they want to pull a prank on someone and use it to block their access to Google, Facebook or some other site, and make them think that it is down, and no longer working. The people using the Hosts file most frequently are web developers who create websites and web apps, which must be tested locally, before publishing them on the internet.
IT professionals also use the Hosts file to block access to specific sites and web resources, on the computers they are managing at work. For example, they can use it to block advertising in their business network, from specific ad networks.
Malware can also use the Hosts file to redirect your web traffic to remotely controlled servers and steal personal information or other data.
I can't edit the Hosts file in Windows! What do I do?
When editing and saving the Hosts file in Windows, you may receive an error message that states: "You don't have permissions to save to this location." This happens because you did not open Notepad or the text editor that you are using, with administrator permissions. Read the sections above and see how to start Notepad with administrator permissions.
After you do that, you can edit the Hosts file without any errors and permission problems.
How do you use the Hosts file in Windows?
Thank you for reading this tutorial. We hope that we have managed to answer all your questions about the Hosts file. Before closing, tell us in a comment, how you plan to use the Hosts file in Windows? Is it for work or just prank on a friend or family member? Comment below and let's share our experiences working with the Hosts file.
