What is "Block Site" extension and how does it work?

This extension keeps an eye on top-level hostname accesses and matches them against a custom blocking list created by the user. If a hostname is on the list, the extension blocks access just before the browser sends the top hostname request to the server. This functionality helps prevent access to a hostname that is not intended to be accessed from your IP address or when you want to block popup websites from opening new tabs that could inject malicious scripts into your browser.

Additionally, you can use the extension to redirect URLs. To use this feature, add a hostname to the blocking list from the options page and enter the FULL URL of the destination domain in the redirect box (including schemes like "http://www.google.com"). The extension extracts the arguments of the original URL and passes them to the destination URL. This functionality, for instance, helps to redirect search results from Google.com to Bing.com. Add "*.google.com" as a new hostname and enter "https://www.bing.com" in the destination field to achieve the redirecting. Don't forget to save your changes. Now, when you search for something in the address bar, you will receive results from Bing.com (Assuming that Google is your default search engine).

Note: If you want to ensure that the blocked remote servers do not receive any connection requests from your browser, uncheck the "Display title of blocked hostnames" option on the options page. With this option checked, the extension sends a request to the server to retrieve the actual page title. This option is only useful for distinguishing blocked tabs if there is no restriction on sending or receiving data from the blocked hostnames.

What is the master password and how can I set it?

When you set the master password from the options page, you can access restricted URLs for a defined duration. Changing any options, such as removing a hostname from the blocking list or adjusting the time interval for temporary accessing hostnames, will require the master password. Setting the master password prevents other users from modifying the extension's preferences on the options page.

It's important to note that with the master password set, you can temporarily unblock a hostname by entering the password in the box displayed on the block page. This grants access to the hostname for a predetermined time (usually 1 minute by default).

How can I block all the sub-domains of a single domain (like www.google.com, ca.google.com, ...)?

Use wildcard in the place of the subdomain. For instance, to block all the Google subdomains use "*.google.com". Here is the list of valid and invalid wildcard matchings:

Why is the destination redirection feature disabled when a wildcard is used in a matching pattern?

The reason for disabling the destination redirection feature is the performance drawback of wildcard matching. The process of wildcard matching is computationally expensive, which is why this extension does not allow it. Instead, you can add multiple rules without using a wildcard to achieve the same matching capability without sacrificing performance.

What's new in this version?

Please check the Logs section.

Is it possible to change the theme of the blocked pages in the extension?

Yes, starting from version 0.1.1, you can select either a dark or a light theme for the blocked pages. You can find the theme selector button at the top right corner of the blocked pages. Once you select the theme, it will persist even after you restart your browser. If you want to apply your styling, use the options page. There is a section called "Custom CSS" where the user can modify the styling of elements on the blocked page. For instance, you can hide a message or change the font or even the colors.

Is it possible to block websites for a specific period only?

Yes, starting from version 0.1.3, there is a new section on the options page allowing you to specify the period and days during which the blocker will be active. By filling out this section, you can block the list of websites for a defined period only. If you need to unblock a website for a particular day, you can remove that day from the list of blocked days.

Is it possible to use this extension to allow only a selected few hostnames while blocking all others?

Yes, the extension offers a reverse mode that you can activate from the options page. When this mode is active, only the hostnames listed in the allowlist will be able to pass through the blockage, and all other hostnames will be blocked.

How can I prevent this extension from being removed or disabled from the Firefox browser?

Create a policies.json file with the following content. This file sits into a directory called distribution within the Firefox installation directory. You can use it to control how users have access to the browser features. For more info visit github.com/mozilla/policy-templates

{
  "policies": {
    "Extensions": {
      "Locked":  ["{54e2eb33-18eb-46ad-a4e4-1329c29f6e17}"]
    }
  }
}

I have a big list of hostnames to be blocked. Can I import them instead of manually adding new rules?

Create a text file anywhere on your computer. Let's call it block.txt. The content of this file is a line-separated list of hostnames to be blocked. Basically, each hostname is placed in a new line. If you would like to add comments, use a new line and start the line with "#" character. The extension simply ignores these lines. If you need to enable redirection, add the complete path to the redirected page after the hostname to be blocked. Note that after using the import button, the list will be added to the rules, but still it is not being applied. You need to press the "Save" button for the changes to actually apply. If for any reason, you would prefer to start over, simply close the options page and reopen it. See the sample below:

  

    
# Line-separated list of hostnames to be blocked. Lines start with "#" are ignored
  
  

    
# hostname to be blocked
    
URL to be redirected to (optional)
  
  

    

  
  

    
www.google.com
    
https://www.bing.com
  
  

    
www.yahoo.com
    

  

Is there a way to temporarily disable the blocking without using the scheduling feature? For instance, if I need to access all websites for a short period.

Yes, starting from version 0.2.3, you can use the right-click context menu on the extension's toolbar button to pause the blocking for a specific duration. If you have set a master password for the extension, you will need to unblock it first. Once the pause is no longer needed, you can use the same menu to resume normal behavior.

Can I set up specific blocking schedules for different domains?

Starting from version 0.2.3, you can define regular expression rules in the options page to specify a specific schedule for domains that match the rule. If a rule is defined, the extension applies the schedule only to URLs that match the rule. If there is no rule defined, it follows the global scheduling. To set up one with a rule, enter the rule in the designated field and wait for the extension to load the information. To delete a schedule with a rule, enter the rule and wait for the extension to load the corresponding schedule, then delete the time section and keep the rule to indicate that you want to delete the rule. You can also edit the settings as a JSON object using a text editor and then load them back into the extension.

Here is a minimal example to block Google.com on Mondays between 07:00 AM to 08:00 AM. Note that the "google.com" hostname is listed on the blocked list as well as it matches to a regular expression in the scheduling list.

{
  "blocked": [
    "google.com",
    "*.google.com"
  ],
  ...
  "schedules": {
    "google\\.com": {
      "times": {
        "Mon": [
          {
            "end": "08:00",
            "start": "07:00"
          }
        ]
      }
    }
  },
  ...
}

Can I use regular expressions to block websites instead of wildcard matching?

Yes, starting from version 0.2.3, you can define a regular expression rule in the "Block a new hostname" field by adding the R: keyword at the beginning of your rule. By doing this, the extension recognizes that you are using a regular expression instead of a wildcard, and applies your rule accordingly. Regular expressions are a powerful tool to create complex patterns for blocking specific domains or keywords.

Can this extension automatically close a popup tab that opens periodically?

Yes, starting from version 0.2.3, the extension provides a specific redirecting keyword, close, which immediately closes any tab that matches a blocking rule. By using this keyword as the redirection destination, the extension can automatically close any popup tab that matches the blocking rule.

Is it possible to use this extension on a corporation to block sites on multiple machines?

As of version 0.3.2, this extension supports managed storage to import settings from the managed preference. An admin user can configure all instances of this extension by setting a managed storage. The PLIST for reading preferences looks like this example. Use your browser managed storage documentation to see how to set up the managed storage.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple/DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>json</key>
  <string>single-line valid JSON string containing all the preferences (use the output of the export button + shift key to generate this string)</string>
</dict>
</plist>

By default, this key is set to false, which causes the extension to overwrite all the preferences only once. If the value of this key is set to true, on each restart the extension overwrites all the preference from the provided JSON string. Note that in case the JSON string is updated by the admin (contains a new GUID), all the preferences will be overwritten once even if the "managed.storage.overwrite.on.start" key is set to false. Also, note that you can set a password while configuring the extension once and this password will prevent all the client machines from altering the preferences later (all clients only access to the HASH of the password so it is safe to set the password on the machine before generating the JSON file).

On the Firefox browser, you need to create a JSON file called {54e2eb33-18eb-46ad-a4e4-1329c29f6e17}.json and placed it inside the ManagedStorage directory. Read more about how to configure Firefox to use the managed storage here. Here is a sample JSON file to block Wikipedia:

{
  "name": "{54e2eb33-18eb-46ad-a4e4-1329c29f6e17}",
  "description": "managed storage for Block Site extension",
  "type": "storage",
  "data": {
    "json": "{\"blocked\":[\"wikipedia.org\",\"*.wikipedia.org\"],\"last-update\":1608787025230,\"managed.storage.overwrite.on.start\":true,\"guid\":\"5f956061-006d-4713-8e33-a2adb7136902\"}"
  }
}

How can I block all websites except one particular site during a specific hour of the day?

Add a general blocking rule that matches every hostname, such as :///* to block all websites. This rule ensures that all hostnames are blocked or considered for blocking by the extension. To unblock a single hostname during a specific hour of the day, add a scheduling rule for that hostname. Before applying the blocking, the extension checks the schedule and if it doesn't match, the blocking is aborted.

For example, if you want to block all websites except example.com between 01:00 and 02:00 every day, you can add a schedule with the regular expression rule example.com and set the "from" time to 02:00 and the "end" time to 01:00 for all days.

Can I block an entire website but allow a specific page on that website using this extension?

Yes, you can use this extension to block an entire website and then whitelist a specific page on that website by adding a regular expression rule with a schedule. First, you can browse the website and use the extension's action button to add the blocking rules. Then, you can go to the options page and add a regular expression rule that matches the entire website and the specific page you want to whitelist. For example, if you want to whitelist a page on example.com, you can add a regular expression like example.com/path/to/whitelisted/page. Next, you can set a schedule for this rule, specifying the time when the page will be unblocked. For instance, you can set the start time to 00:00 and the end time to 00:01, so that the page is blocked for 1 minute a day and unblocked the rest of the time. Alternatively, you can create a regular expression rule that matches the entire website but excludes the specific page you want to whitelist.

Is there a way to prevent a user from bypassing the blocking by deleting the internal storage of the browser?

One way to prevent a user from deleting the internal storage of the browser and bypassing the blocking is by setting the profile directory to read-only. This can be achieved by creating a new user account on your operating system with write access to the profile directory and logging into the read-only user account to run the browser. On Linux, you can use the command "su rw_user -c chrome" to run the browser as the user with write access. This ensures that the user can access the browser and its settings, but cannot modify or delete the profile directory.

Can I schedule blocking based on a different time zone than my browser's? I have set my browser to use GMT for privacy reasons, but I want to block sites based on my local time zone.

Starting from version 0.4.1, you can set a custom offset in minutes in the "Schedule Blocking" section of the options page. This allows you to schedule blocking based on a time zone different from your browser's. The options page for your convenience also displays the calculated time based on the offset you have set.