How to Protect Your Modem from a Denial-of-Service

A Denial of Service (DoS) attack denies a user the access to his device or network. Although a Denial of Service attacker could target anyone, online gamers, e-commerce websites, and Forex traders are most vulnerable to the attacks. This article shows you how DoS attacks may affect modems and how you can protect your modem.

How a DoS works

A DoS (Denial of Service) works much like a DDoS (Distributed Denial of Service). The only difference is that a DoS is launched from a single computer using a single internet connection, while a DDoS is initiated from multiple internet connected devices or computers and may use more than one internet connection. DoS or DDoS come by different names, depending on their mode of attack. Examples include the SYN Flood, Smurf, Ping of Death and so on.

Denial of Service attacker would bombard a device or network with fake traffic or resource requests. This bombardment floods the victim’s system and blocks out legitimate resource requests. In some instances, an attacker forms a botnet that takes advantage of several other internet connected devices and IPs from unsuspecting internet users to cause a Denial of Service. In this case, we call it a Distributed Denial of Service (DDoS).


In recent times, especially since 2016, reports of IP hijack have been frequent. You can easily find IP addresses on specialized search engines like Shodan, just as quickly as you’d call up web pages on Google. Who knows, you just might be on someone’s naughty list.

Attackers have given many reasons for their Denial of service attacks. Hackers may attack a target because they disagree with their victim’s ideas, or want to take out the competition, or are in cyber warfare, and merely want to extort their targets.

On October 21, 2016, someone took advantage of a Mirai botnet where 100,000 devices were used to attack Dyn which made it difficult for them to connect with customers. Spotify, Etsy, Twitter and some other such big websites went off for some hours in the process. Others attacks include the cases of Rio Olympics, Clinton, and Trump Campaign, to mention a few.

How to Detect a DoS Attack Against a Modem


To attack a modem, an assailant targets your IP address. The only way to know that you’re under attack is that your internet connection goes off for no reason. To determine if it is an attack and not just another malfunction, you can follow these steps:

  • Unplug your modem from its power source and the network cable.
  • If you’ve directly connected your modem to your computer, turn off your computer.
  • Allow everything to stay off for at least five minutes.
  • Plug everything back in and then turn them on.

Call your ISP if your internet disconnection persists. Most ISPs will guide their customers through a troubleshooting session to find out if an attacker is, indeed, sending them malicious traffic or resource requests.

How to Protect Your Modem from a DoS Attack


Prevention is always better than cure. Certain things are not curable – so you’d instead prevent the damage. You can protect your modem using a virtual private network (VPN), a secure Firewall, or a mix of both VPN and Firewall – if they work together.

Virtual Private Network (VPN)

The most potent way to prevent a DoS attack on your modem would be to use a VPN. The software hides your real IP address by connecting you to external servers located in remote places across the globe.

A VPN can also protect your modem’s internet connection, thereby averting a DoS attack. When an attacker floods a target with malicious traffic, a VPN absorbs the traffic and makes it difficult to for him to reach the destination directly.

Antiviruses and Firewalls

Yes, a determined hacker may bring down the defenses of an antivirus or anti-malware software and firewall, but it’s good for your initial line of defense. At least, an antivirus program would stop hackers from efficiently detecting your IP. Another benefit of your defense software includes protecting you from being a target if an attacker launches a DDoS attack on gaming servers that you use.


You don’t want your device being used as a botnet to attack other people. Your antivirus and firewall protection can be helpful here, by preventing Trojan viruses from recruiting your device. Install a firewall on all the computers connected to your network, and ensure they download updates automatically.

If you use Windows, you may consider Microsoft Security Essentials. Kaspersky, AVG, Norton, and Avira all have antivirus software for both Mac and Windows. Sophos covers Mac, Windows, and Linux. Other Linux antivirus programs include Comodo and ClamAV.

How to Fix a DoS Attack on Your Modem

Let’s face it. You may not be so lucky to prevent an attack before it happens. If you’ve been unfortunate to be under attack already, then it’s best that you obtain a new IP address. Getting a different IP address from the one under attack is useful because attackers usually configure their botnets to work automatically. Assailant’s botnet keeps attacking your old IP for as long as it’s active online.

Change your IP address straight from your ISP

If you can still connect to the internet while under attack, this is a good way to change the IP address your ISP automatically assigned your computer.


  • Verify what your IP address is from a site like
  • Unplug your modem completely.
  • Since different ISPs have varying expiry time for their IP addresses, you might have to leave your modem unplugged for 10 minutes to 12 hours to be sure that the existing IP has changed. Use the site in step one above to verify if you now have a new IP address. Please note that WhatismyIP may NOT work if your VPN is turned on.

Resetting your Modem’s IP address on Windows

1. Open a command prompt.


2. Type in the command:



You’ll get something like this:


3. Type


as seen in the prompt window in the image below. Hit the Enter key and wait for a short while for your DHCP server to assign your computer a new IP address.



Resetting IP address for Mac

1. Go to your Apple Menu and select System Preferences.


2. Click on Network to select your Network from the DHCP services listed.


3. Select Advanced on the left side box when you click on WiFi or Ethernet (depending on the one you’d used) and go to TCP/IP.


4. Now select on “Renew DHCP Lease.” Configure IPv4 uses DHCP by default.


You may need to restart your computer or modem after making these changes for the changes to take effect.

Upgrade or change your modem

This step is the last resort if everything else fails. If your modem is significantly out of date, upgrade its network security by asking your ISP (or Google) for guidance. Or buy a new modem altogether.


You don’t have to have a business or a company to be attacked with a Denial of Service. Someone might just be practicing his hacking strength and decide to pick your IP to test their skill. In short, the best form of protection is prevention. Resetting your IP can only give temporary relief from attackers. It is best to use a VPN to protects your IP address and internet data traffic from attackers.

Nicholas Godwin
Nicholas Godwin

Nicholas Godwin is a technology researcher who helps businesses tell profitable brand stories that their audiences love. He's worked on projects for Fortune 500 companies, global tech corporations and top consulting firms, from Bloomberg Beta, Accenture, PwC, and Deloitte to HP, Shell, and AT&T. You may follow his work on Twitter or simply say hello. His website is Tech Write Researcher.

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