Fox Web Security add-on for Firefox

Martin Brinkmann
Nov 12, 2015
Updated • Jun 25, 2017
Firefox, Firefox add-ons

Fox Web Security is a neglected add-on for the Firefox web browser that blocks or allows connections to websites based on blocklist information of the three DNS providers Yandex, OpenDNS and Norton ConnectSafe.

There are plenty of security solutions out there for the Firefox web browser to improve the default state of the browser in this regard.

Fox Web Security takes a different approach than most as it uses the DNS system to allow or block connections.

Technically, it checks domain names that the browser connects to against all three DNS database. This is the first request Firefox makes when you connect to domains with the add-on installed, and it will block access to the domain or third-party connections on a site if they are blacklisted by one of the services.

fox web security

It works similar to configuring either one of the domain services as the system's DNS provider, but with the difference that you get aggregate data from three services and that it does not affect the DNS service of the system at all.

You will notice that there is no connection to a site if it is blocked. You can check that yourself using traffic monitors or by simply checking Firefox's network monitor as it does not list any connections if a site is blocked.

The add-on uses the following block types from each provider:

  • OpenDNS - Family Shield
  • Norton ConnectSafe - Security, Pornography and other
  • Yandex - Security and Family

Please note that the protection is not 100%. A site like Playboy may be blocked for instance while all of Reddit's adult only content is not.

That does not mean that the add-on is useless, far from it. First, you may add sites to a personal blocklist or whitelist. That's useful to unlock access to a site that at least one of the DNS services has blocked, or to block a site that they don't block.

dns protection

You may also define the actions the add-on takes when a blocked site is encountered. It differentiates between main and sub requests, and between malicious and adult content blocking.

  • Main request: block, show "unable to connect" error page, do nothing
  • Sub request: block, block only if it comes from a domain that is not the main request, prompt, do nothing

The author notes that the extension has limitations. It does not check IP addresses or local domain names for instance, does not check the content of the data that is transmitted, and that it cannot be used if access to the DNS services that it uses is blocked.

Closing Words

Fox Web Security is an interesting security add-on for Firefox. Since it fires off its checks before the actual connection to the site happens, it is very fast and ensures that connections to the site are only made if it comes up clean.

The downside with this solution, as is the case with all standalone DNS services that offer protection, is that it is not 100%. As mentioned earlier, you may still access adult content for instance as it is not blocked completely.

This means that it can be a useful addition to system security but should not be used as the only means of protection.

software image
Author Rating
5 based on 4 votes
Software Name
Fox Web Security
Software Category
Landing Page

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  1. Daniel said on February 13, 2018 at 1:32 am

    please make this work

  2. Krantesh Singh said on March 16, 2016 at 12:55 am

    How to remove this add on if i forget password which i enabled it when i installed this add-on?
    there is no option like forget your password?
    when i click on “remove”
    it ask for a password.
    now i don’t know, how to fix this.
    this is irritating me.
    sometimes this add-on make me unable to open google or facebook in some different wifi or network.?
    any solution please email me .

    1. Oleksandr said on March 21, 2016 at 7:58 pm
  3. Croatoan said on November 12, 2015 at 2:38 pm

    What about Chrome extension?

    1. Oleksandr said on March 31, 2016 at 4:22 pm

      please test first version :)

      aftert install please click to notification popup and install Fox Web Security (server)

  4. Tom Hawack said on November 12, 2015 at 1:15 pm

    Three DNS servers are informed of an IP’s destinations. Not sure about the privacy issues but if you run ‘Fox Web Security’ then the advantages of DNSCrypt (encrypted dialog with a DNS server chosen within a provided list of DNSCrypt-ready servers) make no sense. Otherwise may be interesting.

  5. John said on November 12, 2015 at 1:14 pm

    Personally, I use:
    – OpenDNS (only some things blocked there, like parked domains etc)
    – MVPS Hosts ( ), which I update automatically with Hostsman ( )
    – SpywareBlaster (immunizing Firefox)
    – Spybot Search & Destroy (Immunize)
    – Eset Smart Security (AV, Firewall, etc)
    – Firefox (well, for now, looking into the alternative browsers).
    – NoScript
    – AdBlock Plus
    – Element Hiding Helper for AdBlock Plus
    – Ghostery
    – Google Search link fix (to prevent OnClick changing of the url to one of their stat sites to “count” your click)
    – HTTPS-Everywhere
    – WoT

    Using the MVPS Hosts will block a lot of the bad stuff locally already. I would not be too keen to use a Russian ISP’s DNS server like what this plugin is using.

  6. Petrovic said on November 12, 2015 at 10:03 am

    Thanks again!

  7. Petrovic said on November 12, 2015 at 9:41 am

    Thanks for sharing this information!
    What is the name of this firefox theme(screenshot)?

    1. Martin Brinkmann said on November 12, 2015 at 10:00 am

      The theme is called FT DeepDark.

  8. CHEF-KOCH said on November 12, 2015 at 9:04 am

    My question is, if we already enable safe-browsing + tracking protection + DNT and so, do this separate addon have any benefit over the integrated mechanism? Because such integrated mechanism are exactly designed to block such things.

    Personally I don’t see any benefit of it, why should I choose/install an addon that possible collect my surf behavior to an untrusted provider, instead of using the trusted Google/Mozilla lists. I mean is there something wrong with it? For me the safe-browsing mechanism is already very strong.

    1. Neal said on November 12, 2015 at 11:27 am

      Theoretically the more combination of blacklist the better your chances of actually blocking something harmful, but I wouldn’t depend on it. Malware domains/sites are constantly shifting so using blacklist is only marginally effective. Out of the various blacklists, safe-browsing is probably the least effective because it constantly being gamed.

    2. Pants said on November 12, 2015 at 9:31 am

      Just an observation … but do google/mozilla provide different categories of safe-browsing (such as malicious, family, pornography – not sure how many more categories could be drummed up ) – answer no. I can see this addon being useful in some circumstances, but personally, I would be tackling this at the network level first.

  9. John said on November 12, 2015 at 8:48 am

    Yes, I Agree this is The best Addon in Firefox.Thanks for sharing this Wonderful information..

  10. CHEF-KOCH said on November 12, 2015 at 8:46 am
    1. Martin Brinkmann said on November 12, 2015 at 8:57 am

      Thanks. Corrected.

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