Defend Your Network: 6 Tips On How to Prevent DDoS Attacks

DDoS, or Distributed Denial-of-Service attacks are one of the most chilling threats enterprises face online.

One minute you can be minding your business online and then next you’re being hit by a mountain of traffic that puts you back to the stone age. Sadly, these attacks are becoming more frequent and that's why you need DDoS protection software. Plus, learning how to stop a DDoS attack is essential.

Why do DDoS attacks happen?

Many enterprises struggle to imagine a reason why someone would attempt to put their network offline. However, there are many motivations behind DDoS attacks. The motives behind these attacks range from bitter ex-employees and political activists to cybercriminals who make a living out of extorting business owners.

Surprisingly, individuals don’t require technical knowledge to launch a DDoS attack directly. Instead, they can hire a cybercriminal to commit a DDoS attack for as little as $5.00. The low cost of launching an attack means that almost anyone can send malicious traffic even if they don’t have any technical knowledge.

No matter what reason someone would have for attacking your company, you need to prepare all the same. Don’t make the mistake of thinking that it could never happen to you because it does to unsuspecting companies every day. Instead, put necessary protections in place, like cybersecurity software solutions, so you can rest easy knowing you're well-prepared in case anything happens. 

Key signs you’re being attacked

Recognizing the signs of a DDoS attack is the first step to preventing downtime. If you experience any of the following problems, then you could be under attack.

• Network traffic spike is one of the most common signs of a DDoS attack. Organizations experiencing sudden inbound traffic increase may be subject to ongoing attacks that overwhelm the network infrastructure and consume more server resources. That's why it's important to monitor traffic patterns and spikes to identify in-progress attacks. 
• Slow access to local and remote files is another typical sign. Since a DDoS attack congests a network infrastructure with malicious traffic, it may increase latency and packet loss. Organizations must keep an eye on network performance degradation and speed of network-dependent activities to understand if they are subject to an attack. 
• Inaccessible website along with error messages like 'service unavailable' is another sign. This happens because servers may crash due to an excessive volume of incoming traffic which causes service unavailability.
• Network log abnormalities can also help an organization understand whether they are subject to a DDoS attack. For example, businesses can look at  repetitive resource requests, too many connection requests from specific internet protocol (IP) addresses, and traffic distribution across network segments to understand if they have been through DDoS attacks. 

If you start seeing any of the signs above, you should take a closer look at what’s going on but don’t panic. Sometimes you’ll experience connectivity issues because of traffic spikes and legitimate usage, so service disruption doesn’t always mean that you’re under attack!

However, if you notice anything unusual or prolonged disruption to the service, you should investigate further. If you are being subjected to a DDoS attack, the earlier you react, the better. 

DDoS prevention methods

POrganizations seeking to prevent DDoS attacks must adhere to network security best practices, adopt proactive security measures, and use specialized DDoS prevention tools. Here are a few methods you can implement at your organization.

• Attack surface reduction limits the number of entry points an attacker uses to exploit a network or system and launch an attack. This DDoS attack prevention method minimizes the attackable surface area by using network segmentation, access control lists (ACL), security assessments, and firewall configurations. Organizations can also implement load balancing software to restrict traffic to and from certain locations, ports, protocols, and applications. 
• Anycast network diffusion uses a network addressing and routing method called anycast network to distribute volumetric traffic spikes across distributed servers. This DDoS attack prevention method redirects traffic to the nearest available server during an attack. This redirection minimizes service disruption while letting an organization deflect malicious traffic with distributed networks. 
• Real-time, adaptive threat monitoring uses log monitoring tools to analyze network traffic patterns, detect unusual activities, and block malicious requests. Organizations using this method combine machine learning algorithms and heuristic analysis to proactively detect threats, counter DDoS attacks, and minimize downtime.
• Caching uses content delivery networks (CDNs) or caching servers to reduce the number of workload requests origin servers tackle. Users can still retrieve information from the cached content. This DDoS attack prevention mechanism stops malicious requests from overloading origin servers, especially during volumetric traffic floods. The result is improved website performance and reduced strain on the infrastructure during an attack. 
• Rate limiting restricts network traffic for a period to prevent specific IP addresses from overwhelming web servers. This mechanism is ideal for tackling application layer or protocol or botnet-based attacks that send too many requests and overwhelm server resources during an attack. Organizations adopting rate limiting can easily block traffic exceeding pre-defined thresholds, maintain system resources, and defend against DDoS attacks. 

6 tips for stopping and preventing a DDoS attack

Preparation is almost always the best line of defense against a DDoS attack. Proactively blocking traffic is better than being reactive. Since preventing a DDoS attack isn’t possible all the time, you should have a combination of prevention and response techniques in place to address an incident with minimal disruption. Ultimately, the faster you or your team reacts, the less damage is done.

1. Change the server IP or call your ISP immediately

When a full-scale DDoS attack is underway, then changing the server IP and DNS name can stop the attack in its tracks. However, if the attacker is vigilant, then they might start sending traffic to your new IP address as well. If changing the IP fails, you can call your internet service provider (ISP) and request that they block or reroute the malicious traffic.

2. Monitor your website traffic

A spike in website traffic is one of the main indicators of a DDoS attack. Using a network monitoring tool that monitors website traffic will tell you the moment a DDoS attack starts up. Many DDoS protection software providers use alerts and thresholds to notify you when a resource receives a high number of requests. While traffic monitoring won’t stop an attack, it will help you to respond quickly and begin mitigation should an attacker target you.

3. Set up redundant network architecture

Setting up your network architecture to be resistant to a DDoS attack is an excellent way to keep your service up and running. You should spread out key resources like servers geographically so that it is more difficult for an attacker to put you offline. That way, even if one server gets attacked, you can shut it down and still have partial service for your users.

4. Use a Web Application Firewall (WAF)

A WAF system is used to filter HTTP traffic between an application and the internet. When a cybercriminal targets a DDoS attack at the application layer, the application firewall automatically blocks malicious HTTP traffic before it reaches your site. You can decide what traffic gets filtered by configuring policies to determine which IP addresses will be whitelisted or blacklisted.

5. Configure firewalls and routers!

Configuring network devices like firewalls and routers is essential for cutting down on entry points into your network. For instance, a firewall will help to stop cyberattackers from detecting your IP address so they won’t have anywhere to send traffic. Similarly, routers have DDoS protection settings and filters that you can use to control the access of protocols and packet types. 

6. Enable geo-blocking (country blocking)

Geo-blocking is the practice of blocking out traffic from foreign countries where DDoS attacks are frequent. The majority of DDoS traffic comes from China, Vietnam, South Korea, and Taiwan, so blocking traffic from these regions could limit your exposure. While attackers can work their way around geo-blocking, it can reduce your vulnerability to overseas botnets.

Prepare for a DDoS attack before it’s too late

Unfortunately, even with all the preparation in the world, a strong DDoS attack is tough to beat. If you're successful in fighting off the attack, you're still likely to suffer some form of disruption. However, with the right preparation in place, you can reduce the likelihood of an attack putting you out of action.

During an attack, all you can do is notify your employees and your customers to explain performance issues. A social media post will let your customers know there's a problem and that you're working on fixing it.

With the right measures in place, you will be able to limit the damage even if you can't prevent it completely. The important thing is to take action and start building up your defenses early. In the event, you do fall victim to an attack keep a log of source IP addresses and other data for future reference in case there's a follow-up attack.

Want to stay safe online? Read our rundown of seven tips on how to recover from any type of cyberattack. 

This article was originally published in 2019. It has been updated with new information.