Protecting Your Website & Servers from DDoS Attacks: A Complete Guide

Short version: a DDoS attack floods your server with requests from thousands of compromised computers (a botnet) until the site goes down. You spot it by extreme slowness, unexplained spikes in CPU, RAM and bandwidth, and traffic from an unusual number of IP addresses. Defend in layers: the free OMC firewall, a dedicated firewall, a CDN such as Cloudflare, monitoring and alerts, non-default ports, VPN-only access, and scaling up resources on the fly.

What is a DDoS attack and why is it dangerous?

A DDoS (Distributed Denial of Service) attack is designed to overload servers and websites until they stop working, using thousands of compromised computers (a botnet) that send abnormal traffic to your site. The possible damage:

• Downtime for your website or services.
• Lost revenue for as long as the site is unavailable.
• Serious harm to your reputation and credibility.

How do you know you are under a DDoS attack?

• The site is extremely slow or completely unavailable.
• Unexplained load on server resources: CPU, RAM and bandwidth.
• A sudden surge of traffic from many IP addresses at once.

How do you protect your website and server from DDoS?

1. The built-in OMC firewall

The free firewall in the OMC console lets you quickly block IP addresses or whole ranges, and set rules that block abnormal traffic.

The OMC firewall is your first layer of defence, at no extra cost.

2. A dedicated advanced firewall (recommended)

For an extra layer, add a dedicated firewall such as Fortinet FortiGate, Sophos XG, Palo Alto Networks or Check Point. A dedicated firewall detects attacks automatically, analyses traffic in real time and blocks fast.

• Enterprise-grade protection.
• Real-time detection and blocking of malicious traffic.
• Smart, proactive management of cyber threats.

3. A CDN and cloud DDoS protection

A CDN such as Cloudflare filters out most malicious traffic before it reaches your server, and adds free SSL, an advanced firewall and limits on suspicious connections. OMC also offers a dedicated anti-DDoS service.

4. Monitoring and early detection

• Use OMC's built-in monitoring tools to catch an attack early.
• Set alerts on traffic anomalies so you can act straight away.

An alert on unusual traffic lets you block before the site goes down.

5. Change default ports

Move sensitive services such as SSH and RDP off their standard ports to custom ones, to cut down targeted attacks.

6. VPN-only access

Restrict access to your servers to VPN only, blocking any unauthorised attempt to reach them.

7. Scale up in an emergency

OMC Cloud lets you add resources quickly, so your server can ride out short or sudden attacks until they are stopped.

What should you do during an active attack?

1. Enable the firewall in the cloud console immediately.
2. Block the offending IP addresses.
3. Add server resources if needed.
4. Contact OMC support for further help.

And day to day:

• Keep every system up to date.
• Use a managed, secure DNS service such as Cloudflare DNS.
• Back up your data regularly so you can recover quickly if needed.

Frequently asked questions

Is the OMC firewall enough against DDoS?

It is a good first layer for blocking addresses and ranges. Against large attacks, add a dedicated firewall, a CDN or an anti-DDoS service.

How do I tell an attack from ordinary heavy traffic?

In an attack, the load arrives all at once from an unusual number of IP addresses, with no business reason such as a campaign or a sale.

Why change the SSH or RDP port?

Automated scanners go after the standard ports first. A custom port sharply reduces the number of attempts.

What should I do first if the site is already down?

Enable the firewall, block the attacking addresses, add resources and contact OMC support.

Conclusion

DDoS attacks are a real threat to every business that runs in the cloud. The right mix of the free OMC firewall, a dedicated firewall and CDN services, together with monitoring and clear procedures, keeps your business online and protected. If you need help, or you are dealing with an attack right now, our support team is always available.