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How to Edit the Hosts File on Mac OS X

Your Mac’s hosts file is a small, but important text document that has the ability to map hostnames to specified IP addresses. Although the modern Internet uses a variety of public and private DNS servers to map IP addresses, the hosts file is a handy way to override those DNS servers, allowing you to manually point a website address to a desired IP address, or block access to a site altogether by pointing to an unused or internal IP address. Here’s how to edit the Mac hosts file on OS X.

Edit Your Mac Hosts File with Text Edit

There are two primary ways to edit the hosts file in Mac OS X. The first is by using TextEdit, since the hosts file is merely a simple plain text document. However, you can’t open the file directly, since it resides in a protected area of the file system. Instead, we need to copy the file to an unprotected location, like the Desktop, edit it, and then copy it back.

To find the hosts file, open Finder and, in Finder’s menu bar, select Go > Go to Folder. In the box, type the following location and press Return.

/private/etc/hosts

Edit Mac Hosts File OS X

A new Finder window will open and your Mac’s hosts file will be selected. Click and drag it out of the Finder window and drop it on your desktop. This will let us freely edit the file.

Change Mac Hosts File OS X

To open it, simply double-click and it will display the file’s contents in TextEdit (or the text editor of your choice). By default, the hosts file is relatively simple. It contains a number of lines of descriptive text which are “commented out” with the pound or number sign (#). For each line, any text after the pound sign is ignored by the computer, making it a good way to add notes and descriptions to your files. It also contains default IP values for localhost and broadcasthost. To edit the file, you’ll add your own lines after broadcasthost.

Modify Hosts File Mac OS X

A popular use for an edited hosts file is to block access to specific websites. In our example, we’ll pretend that the computer we’re using is a work system, and we want to prevent employees from accessing Facebook (because we’re mean). To do this, type the IP address you wish to assign followed by a hostname. In our case, we want to block Facebook so we’ll map www.facebook.com to 0.0.0.0 which, as an invalid IP address, will result in an error. Now, whenever anyone using the Mac tries to go to www.facebook.com, their Web browser will fail to load the page.

Edit Hosts File OS X

Alternatively, you can enter the IP address of a valid site instead of 0.0.0.0, which will result in users attempting to access Facebook being directed to the site of your choosing. To determine a website’s IP address, you can “ping” the site via Terminal. Simply open Terminal and type the following command, replacing “www.website.com” with the website of your choice:

ping www.website.com

Make note of the IP address that’s returned and use it in your Mac hosts file mapping. For example, The New York Times website at www.nytimes.com returns an IP address of 170.149.172.130. If we map that to Facebook in our hosts file, any time someone using the Mac tries to go to Facebook, they’ll see the The New York Times load instead.

Edit Hosts File OS X

You can add as many entries to the hosts file as you wish by entering new mappings on each line. Once you’ve made your desired changes to the hosts file, save it in its current location on the Desktop. Then, drag and drop the hosts file from your Desktop back to its original location at /private/etc. If you’ve closed the Finder window pointing to this directory, simply use the Finder > Go > Go to Folder command, discussed above, to reopen it.

When you drop the hosts file back in its original location, OS X will ask you what to do about the unmodified hosts file that’s already there. Choose “Replace” and then enter your administrative user password to authenticate the transfer.

With the modified hosts file now in place, fire up your Web browser to test the changes. In most cases, the new mapping should work immediately, but if you’re not seeing the correct behavior, you may need to flush your DNS cache. For OS X Lion and OS X Mountain Lion, open Terminal and use the following command. Note that you’ll need to enter your admin password to execute it:

sudo killall -HUP mDNSResponder

For OS X Mavericks, use this command instead:

dscacheutil -flushcache; sudo killall -HUP mDNSResponder

 

Edit Your Mac Hosts File In Terminal With Nano

The above steps are easy enough, but if you want to avoid copying the hosts file you can edit it directly in Terminal using the UNIX Nano Text Editor, which is built in to OS X.

To get started, launch Terminal, type the following command, and press Return. As with all sudo commands, you’ll need to also enter your admin password to execute it:

sudo nano /private/etc/hosts

You’ll now see the hosts file open in the Nano editor. To navigate and edit the file, use the arrow keys on your keyboard.

Edit Hosts File Nano

Just as we did with the TextEdit method, above, we can add, edit, or remove hostname mappings at will. Because we launched Nano using sudo, any changes will be authenticated and saved directly to the original hosts file, without the need to copy it outside of its home directory.

When you’re done making changes, press Control-X to exit the editor, Y to save, and Return to overwrite the existing hosts file. As we mentioned earlier, make sure to flush your DNS cache if you notice that your new mappings aren’t working properly.

Our examples mentioned blocking and redirecting distracting sites in a work environment. You can also use these steps to manually block access to malicious websites or, of course, to play a prank on friends and family members. If you ever make a mistake and you’re not sure how to fix it, you can always restore the default hosts file contents by using one of the methods above to enter the following default information:

##
 # Host Database
 #
 # localhost is used to configure the loopback interface
 # when the system is booting. Do not change this entry.
 ##
 127.0.0.1 localhost
 255.255.255.255 broadcasthost::1 localhost
 fe80::1%lo0 localhost

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  • Scott

    Ok, I tried both of those but when I try the first one (I’m using OSX mavericks) I’m getting this error on dropping the hosts file back in:

    “The Finder can’t complete the operation because some data in “hosts” can’t be read or written.

    (Error code -36)”

    On the second method, using Terminal, I get this at the end:
    [ Error writing /private/etc/hosts: Operation not permitted ]

    Any ideas? I had edited this file before and it worked great but that was before i “upgraded” to Mavericks

    • http://www.tekrevue.com/ TekRevue

      Sounds like something is using or locking the hosts file. I presume you’ve tried restarting, and making sure that no other apps are opened, but give that a shot if you haven’t.

      Also, find the original host file, highlight it, press Command-I (or right-click Get Info) and make sure the “Locked” box is unchecked under General. Also, look under “Sharing & Permissions” and make sure your user account has Read & Write access.

      Try those, and let me know. I’ll keep looking for other solutions.

    • http://www.tekrevue.com/ TekRevue

      Also, this knowledge base article from Apple points to Error Code -36 as possibly being related to a problem with your physical drive. Make sure you have backups of your data and consider running drive maintenance utilities to check the drive integrity.

      http://support.apple.com/kb/HT2433?viewlocale=en_US&locale=en_US

  • Scott

    For anyone else who has locked file problem, I found the answer here: http://superuser.com/questions/40749/command-to-unlock-locked-files-on-os-x
    Thanks for this page and the suggestions!

  • Tom

    Hi, none of this works for me. In fact, ever since I started running the “dscacheutil -flushcache” command, blocking no longer works. I am on mavericks, so I thought the addtion of the second command would save the day, but doesn’t work either. It doesn’t matter if I restart the browser or computer. Nothing works. Is there a reason for this? Have they changed something in Mavericks we’re not looking at?

  • netsi1964

    This is great! Thank you.

    I would like to recommend this page “Ad server hostnames for blocking ads (format: hosts — in hosts file format)” on http://pgl.yoyo.org/adservers/ which is keeping track of many of the advertisement hostnames. It can be a little tricky to find the correct format file, as the service offers lists in a lot of different formats. This one works for me on my OSX Mavericks mac mini: http://pgl.yoyo.org/adservers/serverlist.php?hostformat=hosts&showintro=0&startdate%5Bday%5D=&startdate%5Bmonth%5D=&startdate%5Byear%5D=

    When you paste the list into your hosts you maps any request to host to “localhost” (127.0.0.1) efficiently disabling “any”/many of the annoying advertisements shown on many sites :-)

  • http://arnoldwatson.com Arnold Watson

    The instructions here were AWESOME and had everything I needed to accomplish my task. Thank you!

  • Gary

    Great instructions but I have one issue. When I copy the edited host file back into the “etc folder” it doesn’t ask me to replace. It says to “Authenticate”. After I authenticate it doesn’t request user name and password and nothing happens. The host file remains in its original form. I am running OSX Mavericks.

  • http://bwrightson.tumblr.com bwrightson

    Works, thanks!

  • Mtb4ever

    excellent, thank you so so much!