How to protect your home network from hackers with CUJO

Last Updated: Jan 23, 2023

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In this article, I will show you tips and tricks on how to protect your home network and connected devices from hackers. So you don’t become the victim of a cyber attack. I will also introduce you to CUJO, a smart home firewall for your entire home network.

Update: CUJO has discontinued its AI firewall. That means, the company might not provide future firmware updates. Check out my Bitdefender Box review for an alternative option.

Reviewed Brands and Products

CUJO Smart Firewall
Book Security in the digital world

Why worry about cybersecurity?

Cybersecurity sounds like a problem that large organizations should have to deal with. But the reality is that every day private citizens become the victim of cyber attacks. As a result, cyber- and online security are issues that all individuals who use the Internet should think about.

Every device that you connect to the Internet is potentially vulnerable to becoming the target of an attack. The risk grows the more devices we add to our home networks. In this article, I’ll review CUJO, a smart home firewall that detects and blocks threats as they occur.

Your home is full of smart devices. They are not protected by antivirus, leaving your home open to hackers. CUJO uses machine learning to secure everything from tablets and PCs, to TVs and baby monitors. (CUJO)

If you are an IT security professional, and familiar with the do’s and don’ts of online behavior, you can skip down to the review of CUJO.

Live view of the threat network
A live view of the threat network

If you are new to security in the digital world, check out this new book that I recently got my hands on. It’s an excellent starting point to learn more about the topic and its terminology.

How threats evolved over the years

When floppy disk drives (FDDs) and compact disks (CDs) were the most common external mass storage devices, viruses posed the main threat to computers and networks. I remember when my parents told me not to insert disks into our family computer blindly.

Threat and cyber attacks statistics
Threat statistics

With the proliferation of USB thumb drives, threats continued to rise. In the business world, many organizations started disabling all USB ports to prevent employees from inserting potentially unsafe thumb drives. Some companies went as far as injecting glue into the USB ports of employee computers, just to make sure that they couldn’t plug anything in.

Hackers can access your finances by exploiting security flaws in your connected devices. They sell your banking data to fraudsters. A hacker could cost you everything. (CUJO)

These days, the Internet has taken the place of physical interfaces as the primary gateway for malware, such as viruses, Trojan horses, etc. Additionally, we are no longer dealing with a single device, such as the family PC, that we need to protect, but with dozens of smart devices.

The connected home

The connected home

In our home, we have connected almost 40 devices to the Internet, including:

  • Macs,
  • iPhones and iPads,
  • Printers and scanners,
  • Thermostats,
  • Light bulbs,
  • TVs,
  • Home security cameras and more.

In other words, our home is like a virtual Swiss cheese with an ever-increasing number of holes and entry points that attackers could exploit. Trying to patch each hole individually is virtually impossible. Plus, most smart devices represent an enclosed system that you cannot tinker with.

Devices in our home
Devices in our home

For example, I have no idea what protocols and security mechanisms LIFX or ecobee implemented in their light bulbs and smart thermostats to communicate with their servers. I don’t think it is the case, but they could be using obsolete encryption and hashing algorithms that hackers could exploit to get into our home.

A hacker can trick you into visiting a malicious site and gain access to your email account, hack your cameras, and steal your photos. Exposed and unsecured devices mean it’s a matter of when, not if, you will be hacked. (CUJO)

If I only had Macs, I could install a firewall on each, but the maintenance effort alone would not make that a feasible strategy. There has to be something better, and there is, so stick with me.

What can you do?

Besides tackling the problem with technology, there are a few things you can do to reduce your risk and exposure significantly. In fact, until just recently, the steps I am showing you below were the primary ones I took to remain safe online.

1. Be smart when browsing the web

Verify the URL and certificate before logging in
Verify the URL and certificate before logging in

Back in the days, you had to launch a file with an executable extension (i.e., EXE or BAT on Windows) to get infected with a virus. These days malware hides everywhere: In Word documents, PDF files, and even in web pages. You may not know that, but your web browser also executes programs, such as Java scripts, when you visit a web page. So attackers can sneak malware into web pages to infect your computer when you visit the page.

As a result, you want to be smart about what web pages you visit. Don’t blindly click on search results, especially if you are searching for phrases that hackers often use to lure victims in. Examples of that include “free stuff,” “getting rich quick,” or pornography, just to name a few. The good news is that most modern browsers support Google’s Safe Browsing to identify fraudulent websites. The same is true for major search engines, such as Google and DuckDuckGo, my favorite search engine.

I wouldn’t be surprised if clicking on links was the #1 cause of falling victim to a phishing attack. A phishing attack is when an attacker tricks you into providing personal or sensitive information that the hacker can then use to gain unauthorized access to your accounts.

Hover over the link and you see the fake URL
Fake email: Hover over the link, and you see the phony URL

A classic example is a fake email from your credit card company that asks you to log in to verify something about your account. Of course, as soon as you have logged in to the fake web page, the attacker has your account credentials and can use them to log into your actual credit card account.

The people behind such phishing attacks have become incredibly good at making such emails look legit. For example, you may receive an email that looks like it came from American Express and even the links may look familiar. But if you look closely, for example by hovering your cursor over a link, you can see that there is an intentional mistake in the URL, such as a typo. Instead of americanexpress.com, the URL may point to americanexpres.com (One ‘s‘ is missing). That fake URL could be owned by the attacker and hosts a webpage that looks like a replica of the legit page.

My advice is to never click on any links or URLs you receive via email unless you are confident they are legit. Instead, open a browser and type in the URL in the address bar manually. In the example above, I would enter americanexpress.com, verify the certificate via the lock icon and then log into my account.

3. Don’t blindly open emails and attachments

Malicious email with attachment
Malicious email with an attachment

You should treat attachments similar to how you treat links. That is important because attachments are another potential source of malware that can infect your device as soon as you attempt to open them. As a rule of thumb, never open an attachment from an unknown sender. If you get an email with an attachment claiming to be from your bank, even though you don’t have a relationship with that bank, delete the email.

But even if you know the sender, don’t open the attachment if you didn’t expect to receive it.

If my mom tells me that she is going to send me a recipe as a Word document via email, it is probably safe to open the document. But if I receive such an email unannounced, I would ask my mom about it first, before opening it. Why? It is because hackers may have broken into my mom’s email account and started sending out infected emails to everybody in her address book. So be smart about what you open.

4. Keep your devices patched and up to date

Enable Automatic Updates in macOS
Enable Automatic Updates in macOS

No operating system or application is free of bugs, but many vendors are quick to patch vulnerabilities in their software. So it is crucial to install patches and updates immediately. I would even argue it is best to configure your device to download and install updates automatically.

Of course, sometimes vendors send out bad updates that may break something, but for most users, that’s better than having vulnerabilities remain unpatched.

5. Take privacy and security more seriously online than offline

Unless you live in the countryside, I am sure you lock your doors at night and make sure your home is secured before you go to bed. That’s common sense, and it reduces the risk of an opportunistic attacker entering your home.

Unfortunately, many users are far more careless when it comes to keeping them and their devices safe on the Internet. I would argue that you are more exposed online than you are offline. As a result, you should take your online privacy and security at least as seriously as you do offline.

6. Choose your operating system wisely

Image by AV-TEST

Many Apple fans would argue that Macs are more secure than their Windows-based counterparts. I agree that most Unix-based operating systems, such as macOS, are more secure by design. But that doesn’t mean that macOS doesn’t have bugs and vulnerabilities that hackers can exploit.

However, it is a fact that hackers have traditionally focused on Windows. That is because there are significantly more PCs in the market than there are Macs. It’s simple economics. If I want to get the most bang for my buck, I create a virus for Windows and not for Macs. But Mac malware has been on the rise in the past few years and using macOS is no longer a guarantee of safety if you don’t act smart online.

I am in IT security and while that doesn’t make me invincible, knowing about potential threats and how to behave online has kept me safe so far. In case you wonder, I am no fan of anti-virus software and haven’t used one in years. Anti Virus software slows your computer down and makes your operating system even more vulnerable to man-in-the-middle attacks and more.

What else can you do?

If you carefully follow the steps above, you can reduce the risk of becoming a victim of a cyber attack. Unfortunately, even when you do everything right, you may still get hacked. For example, an otherwise trusted website may get infiltrated resulting in malware being downloaded to your computer when you visit it. Or the email account of someone from your address book gets hacked and you get an unsuspicious attachment from that person containing a virus. If you notice the problem right away, you can at least take preventive measures, but often users don’t even know that they have fallen victim to a cyber attack. For such cases, you need another layer of protection that covers every single device on your home network, like a big umbrella.

Traditionally, PC security software, like antivirus or anti-malware, is designed to only protect you the device it’s installed on. With so many connected devices in your home, you and your family’s personal lives are now on display through the networked home gadgets you have. Once connected to your router, CUJO smart firewall protects your entire home from nosy and unwanted intrusions.

That’s where CUJO, a smart intrusion detection, and prevention solution for your home network comes into the picture.

CUJO – Home Network Security Firewall

CUJO's happy eyes indicates that everything is OK
CUJO’s happy eyes indicate that everything is OK

CUJO is a smart firewall that protects all devices on your home network from threats and attacks that originate from the Internet. It uses machine learning to detect threats and abnormal behavior.

CUJO is a smart firewall that keeps your connected home and business safe from cyber threats so that you can stay secure and private online.

From a technical perspective, CUJO consists of a hardware appliance, an app, and a cloud service. The cloud service acts as the Intrusion Detection System (IDS), and the appliance works as the Intrusion Prevention System (IPS). In a nutshell, CUJO provides home network security monitoring and threat detection without requiring manual interaction.

How does CUJO work?

CUJO sits between the modem of your Internet Service Provider (ISP) and your remaining connected devices, such as wireless access points, computers or other IoT devices. IoT stands for Internet of Things and includes smart thermostats, connected light bulbs, etc.

The CUJO platform
The CUJO platform

Depending on how you wire and configure CUJO, all Internet traffic that enters your home via the modem passes through CUJO. That way, CUJO can inspect each network packet for potential threats and block them before they reach your devices or harm them.

For that to work, CUJO continually sends data packet headers (metadata) to the cloud for inspection and analysis. It does not transmit the actual content of your Internet traffic to the cloud. That’s important from a data privacy perspective!

Let me give you an example: If you open a browser on your computer and go to google.com, then CUJO would see that and would let its cloud service know that you went to Google. But the cloud service would not know what you searched for and what search results Google showed you.

Safe browsing notification on iOS
Safe browsing notification on iOS

Of course, CUJO encrypts all data it transfers to and receives from the cloud with AES-256, one of the most robust symmetric encryption algorithms available today.

CUJO works with the following network setups:

  • WiFi router
  • Modem and router as separate devices (that’s what I have)
  • Modem and router as one device
  • Wireless extender or access point in addition to your router

Setup with AT&T Arris modem and AmpliFi router

For my fiber-glass Internet connection, AT&T provided an ARRIS BGW201-700 modem. Behind the modem, I have an AmpliFi HD mesh router (review) and several mesh points to cover my home with WiFi.

CUJO connected to modem

Before I got CUJO, the AmpliFi router handled DHCP and Network Address Translation (NAT), while the Arris modem was, more or less, a passthrough device. My goal was to position CUJO between the Arris modem and the AmpliFi router. For that to work, I switched the AmpliFi router into bridge mode and let the Arris modem handle DHCP.

If that’s all too technical for you, don’t worry! CUJO has excellent step-by-step guides on how to integrate its appliance into your specific network setup. Even better, they offer a proactive support team to guide you through each step. When I plugged in CUJO and signed up for an account, I had to provide a phone number. Minutes later, I got a call from CUJO support asking if I needed help with the configuration. I had never seen anything like that before and was pleasantly surprised at how proactive their support team was.

Blocked threats
Blocked threats


What I like about CUJO is that it does its job in the background. It stays out of my way until it detects a threat and sends me a notification to my smartphone. There are no firewall rules to configure and no manual updates necessary.

  • Guards all devices
  • Offers parental controls
  • Protects against hacking, fraudulent sites & malware
  • Supports speeds of up to 1 gigabit per second
  • Automatic software updates

CUJO handles all of that without requiring my intervention. Even better, it constantly learns thanks to the machine learning capabilities of the CUJO cloud. That is possible because the cloud service analyzes an incredible amount of data every day to learn about how individual devices behave or are supposed to act. If those patterns change, there could be a problem and CUJO can then block those potential threats before they can harm you.

CUJO provides overwatch
CUJO provides overwatch

Additionally, CUJO shares threat information among all of its devices. So when one CUJO appliance detects a threat, all other CUJO users are automatically protected against it.

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Comparison with traditional solutions

So how does CUJO compare to conventional solutions, such as firewalls, anti-virus solutions or a standard wireless router?

CUJO vs firewall
CUJO vs. traditional solutions

In a nutshell, CUJO is much more than a firewall; it is like a commercial intrusion detection and prevention solution but for your home.

Troubleshooting Tips

After having used CUJO for a few months, I noticed that some pages were loading slower than usual and CUJO would alert me to potential threats on a daily basis. It turns out that CUJO is relatively aggressive with blocking ad networks and as a result, it slowed down pages that use a lot of ads, such as Facebook or Amazon. So I reached out to CUJO support and asked for help. They cleared all access rules and blocked sites from my CUJO applianced and suggested to run a malware scan on my Windows and Android devices. I don’t own anything but macOS and iOS devices, and so I skipped that step.

After rebooting CUJO, my internet speed appears to be back to normal. I will update this article again in a few weeks to report if anything changes.

Why I use CUJO and why you should too

Dynamic duo: CUJO and AmpliFi
Dynamic duo: CUJO and AmpliFi

We have a continually growing number of connected devices in our household. And I realized that I only have direct control over a fraction of those devices, including my two Macs and, to a degree, our iOS devices. Everything else is a black box for me, and I have to trust that the vendor did a good job of securing the device.

So I needed a solution that could protect all of my devices without requiring me to stay on top of new threats and rule changes constantly. CUJO fits that bill because it offers continuous protection for all of my connected devices. While that doesn’t mean that I can let my guard down and start acting irresponsibly online, I feel comfortable that if I ever make a mistake, this smart home network security appliance has my back.

CUJO is available from the company’s online store or Amazon for $249 + free shipping. If you own CUJO, let me know how you like it by leaving a comment below. If you found my article useful, or even if you didn’t, I want to hear from you. So don’t hesitate to leave me a comment or send me an email!

23 thoughts on “How to protect your home network from hackers with CUJO”

  1. Thank you guys for the input. I’ve successfully set up the CUJO with my eero and FIOS. Too bad CUJO cancelled all their phone tech support but I was able to find info online and bridge everything basically. It’s an excellent product and recommended to everyone I know that asks about home network security.

  2. Hi. Thanks for the review. I know this review is quite old but I’m a new CUJO user here. CUJO has since removed phone tech support and it’s only available via email. Wanted your advice on my setup. I have FIOS and Eero and CUJO. Per their instructions, FIOS router is bridged with WiFi off. LAN 1 goes to CUJO in DHCP mode, lan 2 goes to eero network. The only devices I see on CUJO are my FIOS set top boxes and my eero system as a whole but not any Wi-Fi devices connected to it. I’m unsure if CUJO is actually working even though it’s smiling. Thoughts?

    • Hi Chito!

      I haven’t used CUJO in such a setup, but since all of your traffic is routed through CUJO it should be working. The reason why you don’t see any of your other devices is because your Eero is set to routing instead of bridging. If you need full control over your wireless devices, you might have to enable bridge mode on Eero too.

    • Hi Chito. Your Cujo is surely working. What happens is that you have it between your router/mesh system and you modem/gateway to the internet. What this means is that Cujo is still protecting everything going through your Eero system, but cannot tell which device is having what blocked, because it only sees traffic coming from the Eero system (does this make sense?). I, on the other hand, have it AFTER my Orbi system, so the Cujo blocks the same as yours, but has visibility of each individual device (including router and satellites), thus I know what device was attempting to connect to a dangerous address. In my experience with Cujo (just about 2 months now), it is a very aggressive little device when it comes to blocking threats, but you have the option to unblock certain addresses if you choose to, which makes it a bit more flexible.
      I hope I was able to clarify this for you.
      Michael, I just came across your site by chance, and I have to say that your review of the Cujo is very detailed and realistic based in my own experience with it.
      People like you are a great asset for some of us “noobs” in the tech world.
      Thank you.

  3. Thanks for the review. Three languages, an I.T pro, a crossfitter, and a DAD?! Good stuff! I’m also an I.T. Sec pro (a bit new to it), a dad, and a fitness fanatic (working on getting to crossfit status, but my body is telling me NO!). I actually got a CUJO from the creators nephew! I’ve been so busy, that I never got a chance into looking into how it works. Seems like a home version of Darktrace and the like. I agree, their support is really really good. I got them through the app in a matter of seconds and they got me up and running in a few minutes. The setup is much more complicated than your standard router modem setup. My suggestion is not to try it yourself. Just click the tech support button and you’ll be good to go!

  4. Hi Michael,

    Do you keep recommend Cujo? Did you have any problem? Performance issue ? Which Setup do you recommend? does Cujo works good with gateway on the network?

    • Hi Leandro,

      I am still recommending CUJO, but I am currently in the process of evaluating other solutions (like Fingbox) and re-evaluating CUJO because my network infrastructure has changed over the past months. So please stay tuned for further updates. To get a notification when the updates article gets released, feel free to sign up for my blog updates list via Contact > Newsletter

      • Hey, Michael,
        I had the FingBox about a year before I got my Cujo, and they are 2 very different devices. The FingBox will not block any potentially dangerous sites but will eliminate the possibility (should you give it the permission) of random devices accessing your network without your permission when in the vicinity of your network (wireless or hardwired).
        I have both devices working together. The ONLY problem I have is that now I need to have the “auto-block” of new devices disabled in my FingBox, because Cujo generates virtual MAC addresses a few times a day, and while I had “auto-block” disabled, this was effectively rendering my network, and internet, unusable, because FingBox would block the new MAC Address for the Cujo, and Cujo is my DHCP server. Imagine the chaos when that started happening.
        Anyway, I thought I would share my own experience with these 2 devices. Maybe I can get a tip from you on how to avoid this issue while being able to enable “auto-block” in my fingbox again (assuming that is even possible)?

  5. Informative article. How does Cujo compare to Fingbox? I have Fingbox which I like because Synology router is missing some of those features found in Fingbox.

  6. I bought and installed Cujo for a private non-business client I do tech support for. Over the past nine months my support calls have diminished significantly and as a bonus – with his consent – I can monitor his devices on his network from my ipad – regardless of where I am. The only maintenance work is to continue to coach good safe internet usage and to check threats as notified. Tech support has always exceeded my expectation in correcting over protection and resolving any issues with voip devices and hearing impaired support devices. Its like getting corporate level support for your entire IOT for a one time purchase prices. It doesn’t get easier or cheaper than this – I spent years as a corporate IT security professional.

  7. I got Cujo and connected with amplify and att uverse gateway. My internet is slowing down and looks lime Cujo is blocking a lot of our activity. I think it is too protective. Its blocking even it doesn’t have too. We are back to Amplify and let my mac firewall by itself. So far so good. I may activate Cujo again but for the meantime my wife and kid don’t get Cujo love.

      • Thanks, Michael,

        I thought we are the only one experiencing CUJO overprotection because it looks like everybody is happy with their CUJO. Keep me posted buddy.


        • Hi Raymond!

          I reached out to CUJO support and they cleared my access lists from the CUJO appliance. After rebooting CUJO, everything seems to be back to normal. You may want to give that a shot!

  8. Once again Michael, you are a reliable source of useful technology. I’m very thankful for your efforts at keeping this blog going. I went ahead and ordered a Cujo the same day I read the review. I bought it for $199.00 at Amazon. Due to the topography of my home network, I ran into a problem for which I could not find at answer at Cujo’s online faq. To my surprise, out of the blue, I received an 800# call from Cujo’s tech while registering the product. The guided me through the fix and solved the problem. Subsequently, I did something on my own that disrupted my network. I called them again and in a few minutes fixed the problem I created. It has been now over a week with the Cujo. It has already detected a couple of phishing attempts that otherwise could have gone unnoticed. Right then, right there, it more than paid for itself. This is an amazing technology with an amazing tech support. I can’t wait to see what this company comes out next!… and Michael, keep reviewing wonderful products and technology!

  9. Thanks Michael. I ordered Cujo (2nd Gen) at Amazon for $199. I’ll let you know how it works for me. Currently my AmpliFi is the one providing DHCP in my network.

  10. Only other one I am aware of is the Bitdefender Box (https://www.bitdefender.com/box/) – same sort of technology. It comes with a one year subscription to their updates etc, $99/yr thereafter. I suspect if you fail to renew the box either becomes a plastic brick or best case, all the vulnerability protection will be out of date (and therefore worthless).

  11. Hi Michael, did you notice any performance impact on your Internet activity after placing the CUJO?
    Is it possible to block access to for example youtube (via apps or browser) using the parental controls? I am still missing this functionality in my Amplifi HD.

    • Hi Kees!

      I haven’t noticed any performance issues. But in reality, it’s hard to judge because even the raw speed of my fiber connection fluctuates.

      Using the CUJO app, you can block access to certain content categories (News, Social, Streaming Media etc) or to individual web pages.


  12. Great post Michael! I completely agree that internet security is more important than ever before and will continue to be/should be one of our biggest concerns for the foreseeable future. I know that you like CUJO, but are there any competitors that do something similar? Also how long do you think CUJO will last considering how rapidly technology advances and with it the capabilities of hackers?

    • Hi Eric!

      Honestly, I would expect competition, but I haven’t looked around much yet. In fact, CUJO is the first device in that category I looked at. I can’t tell you how long they are going to last as an organization, but the technology looks sufficiently flexible to me to adapt to future scenarios. Maybe you’ll need a new (more powerful) appliance in the future, but their cloud service can be what they want it to be.


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